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基于Spring?Boot的線程池監(jiān)控問題及解決方案

 更新時間:2022年03月14日 10:25:37   作者:大魔王先生  
這篇文章主要介紹了基于Spring?Boot的線程池監(jiān)控方案,本文給大家介紹的非常詳細(xì),對大家的學(xué)習(xí)或工作具有一定的參考借鑒價值,需要的朋友可以參考下

前言

這篇是推動大家異步編程的思想的線程池的準(zhǔn)備篇,要做好監(jiān)控,讓大家使用無后顧之憂,敬畏生產(chǎn)。

為什么需要對線程池進(jìn)行監(jiān)控

Java線程池作為最常使用到的并發(fā)工具,相信大家都不陌生,但是你真的確定使用對了嗎?大名鼎鼎的阿里Java代碼規(guī)范要求我們不使用 Executors來快速創(chuàng)建線程池,但是拋棄Executors,使用其它方式創(chuàng)建線程池就一定不會出現(xiàn)問題嗎?本質(zhì)上對于我們來說線程池本身的運(yùn)行過程是一個黑盒,我們沒辦法了解線程池中的運(yùn)行狀態(tài)時,出現(xiàn)問題沒有辦法及時判斷和預(yù)警。面對這種黑盒操作必須通過監(jiān)控方式讓其透明化,這樣對我們來說才能更好的使用好線程池。因此必須對線程池做監(jiān)控。

image.png

如何做線程池的監(jiān)控

對于如何做監(jiān)控,本質(zhì)就是涉及三點(diǎn),分別是數(shù)據(jù)采集、數(shù)據(jù)存儲以及大盤的展示,接下來我們分說下這三點(diǎn);

數(shù)據(jù)采集

采集什么數(shù)據(jù),對于我們來說需要采集就是黑盒的數(shù)據(jù),什么又是線程池的黑盒數(shù)據(jù),其實(shí)也就是整個線程處理的整個流程,在整個流程中,我們可以通過ThreadPoolExecutor中的七個方法獲取數(shù)據(jù),通過這七個方法采集到的數(shù)據(jù)就可以使線程池的執(zhí)行過程透明化。

  • getCorePoolSize():獲取核心線程數(shù);

  • getMaximumPoolSize:獲取最大線程數(shù);

  • getQueue():獲取線程池中的阻塞隊(duì)列,并通過阻塞隊(duì)列中的方法獲取隊(duì)列長度、元素個數(shù)等;

  • getPoolSize():獲取線程池中的工作線程數(shù)(包括核心線程和非核心線程);

  • getActiveCount():獲取活躍線程數(shù),也就是正在執(zhí)行任務(wù)的線程;

  • getLargestPoolSize():獲取線程池曾經(jīng)到過的最大工作線程數(shù);

  • getTaskCount():獲取歷史已完成以及正在執(zhí)行的總的任務(wù)數(shù)量;

除了我們了解的這些流程以外,ThreadPoolExecutor中還提供了三種鉤子函數(shù),

  • beforeExecute():Worker線程執(zhí)行任務(wù)之前會調(diào)用的方法;

  • afterExecute():在Worker線程執(zhí)行任務(wù)之后會調(diào)用的方法;

  • terminated():當(dāng)線程池從運(yùn)行狀態(tài)變更到TERMINATED狀態(tài)之前調(diào)用的方法;

對于beforeExecute和afterExecute可以理解為使用Aop監(jiān)聽線程執(zhí)行的時間,這樣子我們可以對每個線程運(yùn)行的時間整體做監(jiān)控,terminated可以理解為線程關(guān)閉時候的監(jiān)控,這樣我們就可以整體獲取采集到線程池生命周期的所有數(shù)據(jù)了。

數(shù)據(jù)存儲以及大盤的展示

對于存儲我們這個比較適合采用時序性數(shù)據(jù)庫,此外現(xiàn)在很多成熟的監(jiān)控產(chǎn)品都可以滿足我們大屏展示的訴求,這里推薦下美團(tuán)Cat和Prometheus,這里不展開進(jìn)行講解,大家可以根據(jù)自己公司的監(jiān)控產(chǎn)品進(jìn)行選擇,對于不同的方案采取的存儲形式會有些差異,甚至自己都可以自定義實(shí)現(xiàn)一個功能,反正難度不大。

進(jìn)一步擴(kuò)展以及思考

在實(shí)際的項(xiàng)目開發(fā)中我們會遇到以下場景:

  • 不同的業(yè)務(wù)采用同一個線程池,這樣如果某個服務(wù)阻塞,會影響到整體共用線程池的所有服務(wù),會觸發(fā)線程池的拒絕策略;

  • 流量突然增加,需要動態(tài)調(diào)整線程池的參數(shù),這個時候又不能重啟;

針對這兩種場景,我們對線程池再次進(jìn)行了深入的思考:

  • 如何合理配置線程池參數(shù);

  • 如何動態(tài)調(diào)整線程池參數(shù);

  • 如何給不同的服務(wù)之間做線程池的隔離;

如何合理配置線程池參數(shù)

關(guān)于這個問題面試的時候也是經(jīng)常被問到,我只能說這個問題開始就是一個坑,針對與CPU密集型和I/O密集型,線程池的參數(shù)是有不同設(shè)計(jì)的,也不是遵守幾個公式就可以搞定,當(dāng)然可以參考,我認(rèn)為對于線程池合理的參數(shù)的配置是經(jīng)過多次調(diào)整得到的,甚至增加和減少業(yè)務(wù)都會影響一些參數(shù),我不太建議大家每天背書式的CPU密集型就是N+1,非CPU密集型就是2N,因此我們更希望看到線程池動態(tài)配置。

如何動態(tài)調(diào)整線程池參數(shù)

關(guān)于如何動態(tài)調(diào)整線程池,還是回到我們場景問題的解決上,對于流量突增核心就是提升線程池的處理速度,那如何提升線程池的處理速度,有兩種方式,一種是加快業(yè)務(wù)的處理,也就是消費(fèi)的快,顯然這種在運(yùn)行的業(yè)務(wù)中我們想改變還是比較困難,這個可以作為復(fù)盤的重點(diǎn);還有一種就是增加消費(fèi)者,增加消費(fèi)者的重點(diǎn)就是調(diào)整核心線程數(shù)以及非核心線程數(shù)的數(shù)量。

img

居于這種思考,這個時候我們需要看下ThreadPoolExecutor線程池源碼,首先看下開始定義的變量,通過變量的設(shè)計(jì)我們就會發(fā)現(xiàn)大師就是大師,大師通過AtomicInteger修飾的ctl變量,高3位存儲了線程池的狀態(tài),低29存儲線程的個數(shù),通過一個變量完成兩件事情,完成狀態(tài)判斷以及限制線程最大個數(shù)。使用一個HashSet存儲Worker的引用,而Worker繼承了AbstractQueuedSynchronizer,實(shí)現(xiàn)一個一個不可沖入的獨(dú)占鎖保證線程的安全性。

img

//用來標(biāo)記線程池狀態(tài)(高3位),線程個數(shù)(低29位)?????
private?final?AtomicInteger?ctl?=?new?AtomicInteger(ctlOf(RUNNING,?0));
//工作狀態(tài)存儲在高3位中
private?static?final?int?COUNT_BITS?=?Integer.SIZE?-?3;
//線程個數(shù)所能表達(dá)的最大數(shù)值
private?static?final?int?CAPACITY???=?(1?<<?COUNT_BITS)?-?1;
//線程池狀態(tài)
//RUNNING?-1?能夠接收新任務(wù),也可以處理阻塞隊(duì)列中的任務(wù)
private?static?final?int?RUNNING????=?-1?<<?COUNT_BITS;
//SHUTDOWN?0?不可以接受新任務(wù),繼續(xù)處理阻塞隊(duì)列中的任務(wù)
private?static?final?int?SHUTDOWN???=??0?<<?COUNT_BITS;
//STOP?1?不接收新任務(wù),不處理阻塞隊(duì)列中的任務(wù),并且會中斷正在處理的任務(wù)
private?static?final?int?STOP???????=??1?<<?COUNT_BITS;
//TIDYING?2?所有任務(wù)已經(jīng)中止,且工作線程數(shù)量為0,最后變遷到這個狀態(tài)的線程將要執(zhí)行terminated()鉤子方法,只會有一個線程執(zhí)行這個方法;
private?static?final?int?TIDYING????=??2?<<?COUNT_BITS;
//TERMINATED?3?中止?fàn)顟B(tài),已經(jīng)執(zhí)行完terminated()鉤子方法
private?static?final?int?TERMINATED?=??3?<<?COUNT_BITS;
//任務(wù)隊(duì)列,當(dāng)線程池中的線程達(dá)到核心線程數(shù)量時,再提交任務(wù)?就會直接提交到?workQueue
private?final?BlockingQueue<Runnable>?workQueue;
//線程池全局鎖,增加worker減少worker時需要持有mainLock,修改線程池運(yùn)行狀態(tài)時,也需要
private?final?ReentrantLock?mainLock?=?new?ReentrantLock();
//線程池中真正存放worker的地方。
private?final?HashSet<Worker>?workers?=?new?HashSet<Worker>();
private?final?Condition?termination?=?mainLock.newCondition();
//記錄線程池生命周期內(nèi)?線程數(shù)最大值
private?int?largestPoolSize;
//記錄線程池所完成任務(wù)總數(shù)
private?long?completedTaskCount;
//創(chuàng)建線程會使用線程工廠
private?volatile?ThreadFactory?threadFactory;
//拒絕策略
private?volatile?RejectedExecutionHandler?handler;
//存活時間
private?volatile?long?keepAliveTime;
//控制核心線程數(shù)量內(nèi)的線程?是否可以被回收。true?可以,false不可以。
private?volatile?boolean?allowCoreThreadTimeOut;
//核心線程池?cái)?shù)量
private?volatile?int?corePoolSize;
//線程池最大數(shù)量
private?volatile?int?maximumPoolSize;

我們的重點(diǎn)看的是volatile修飾的corePoolSize、maximumPoolSize以及keepAliveTime,當(dāng)然threadFactory和handler也可以看下,不過這兩個不是我們解決動態(tài)調(diào)整線程池的關(guān)鍵。對于這些volatile修飾的關(guān)鍵的變量,從并發(fā)角度思考的,必然是有并發(fā)讀寫的操作才使用volatile修飾的,在指標(biāo)采集中我們看到其get的方法,對于寫的操作我們可以猜測肯定提供了set的方式,這個時候我們可以搜索下setCorePoolSize,果不其然我們真的搜索到了。

????public?void?setCorePoolSize(int?corePoolSize)?{
????????if?(corePoolSize?<?0)
????????????throw?new?IllegalArgumentException();
????????int?delta?=?corePoolSize?-?this.corePoolSize;
????????this.corePoolSize?=?corePoolSize;
????????//新設(shè)置的corePoolSize小于當(dāng)前核心線程數(shù)的時候
????????//會調(diào)用interruptIdleWorkers方法來中斷空閑的工作線程
????????if?(workerCountOf(ctl.get())?>?corePoolSize)
????????????interruptIdleWorkers();
????????else?if?(delta?>?0)?{
????????????//當(dāng)設(shè)置的值大于當(dāng)前值的時候核心線程數(shù)的時候
????????????//按照等待隊(duì)列中的任務(wù)數(shù)量來創(chuàng)建新的工作線程
????????????int?k?=?Math.min(delta,?workQueue.size());
????????????while?(k--?>?0?&&?addWorker(null,?true))?{
????????????????if?(workQueue.isEmpty())
????????????????????break;
????????????}
????????}
????}

接下來我們看下interruptIdleWorkers的源碼,此處源碼使用ReentrantLock可重入鎖,因?yàn)閃orker的是通過一個全局的HashSer存儲,這里通過ReentrantLock保證線程安全。

????private?void?interruptIdleWorkers(boolean?onlyOne)?{
????????//可重入鎖
????????final?ReentrantLock?mainLock?=?this.mainLock;
????????mainLock.lock();
????????try?{
????????????for?(Worker?w?:?workers)?{
????????????????Thread?t?=?w.thread;
????????????????if?(!t.isInterrupted()?&&?w.tryLock())?{
????????????????????try?{
????????????????????????//中斷當(dāng)前線程
????????????????????????t.interrupt();
????????????????????}?catch?(SecurityException?ignore)?{
????????????????????}?finally?{
????????????????????????w.unlock();
????????????????????}
????????????????}
????????????????if?(onlyOne)
????????????????????break;
????????????}
????????}?finally?{
????????????mainLock.unlock();
????????}
????}

接下來我們在驗(yàn)證一下是否存在其他相關(guān)的參數(shù)設(shè)置,如下:

????public?void?setMaximumPoolSize(int?maximumPoolSize)?{
????????if?(maximumPoolSize?<=?0?||?maximumPoolSize?<?corePoolSize)
????????????throw?new?IllegalArgumentException();
????????this.maximumPoolSize?=?maximumPoolSize;
????????if?(workerCountOf(ctl.get())?>?maximumPoolSize)
????????????interruptIdleWorkers();
????}
????public?void?setKeepAliveTime(long?time,?TimeUnit?unit)?{
????????if?(time?<?0)
????????????throw?new?IllegalArgumentException();
????????if?(time?==?0?&&?allowsCoreThreadTimeOut())
????????????throw?new?IllegalArgumentException("Core?threads?must?have?nonzero?keep?alive?times");
????????long?keepAliveTime?=?unit.toNanos(time);
????????long?delta?=?keepAliveTime?-?this.keepAliveTime;
????????this.keepAliveTime?=?keepAliveTime;
????????if?(delta?<?0)
????????????interruptIdleWorkers();
????}
????public?void?setRejectedExecutionHandler(RejectedExecutionHandler?handler)?{
????????if?(handler?==?null)
????????????throw?new?NullPointerException();
????????this.handler?=?handler;
????}

這里我們會發(fā)現(xiàn)一個問題BlockingQueue的隊(duì)列容量不能修改,看到美團(tuán)的文章提供的一個可修改的隊(duì)列ResizableCapacityLinkedBlockingQueue,于是乎去看了一下LinkedBlockingQueue的源碼,發(fā)現(xiàn)了關(guān)于capacity是一個final修飾的,這個時候我就思考一番,這個地方采用volatile修飾,對外暴露可修改,這樣就實(shí)現(xiàn)了動態(tài)修改阻塞隊(duì)列的大小。

img

如何給不同的服務(wù)之間做線程池的隔離

img

關(guān)于如何給不同服務(wù)之間做線程池的隔離,這里我們可以采用Hystrix的艙壁模式,也就是說針對不同服務(wù)類型的服務(wù)單獨(dú)創(chuàng)建線程池,這樣就可以實(shí)現(xiàn)服務(wù)之間不相互影響,不會因?yàn)槟硞€服務(wù)導(dǎo)致整體的服務(wù)影響都阻塞。

實(shí)現(xiàn)方案

聊了這么多前置的知識儲備,接下來我們來聊聊實(shí)現(xiàn)方案,整體的實(shí)現(xiàn)方案我們建立在Spring Boot的基礎(chǔ)實(shí)現(xiàn),采用Spring Cloud刷新動態(tài)配置,采用該方式比較合適單體應(yīng)用,對于有Appllo和Nacos可以通過監(jiān)聽配置方式的來動態(tài)刷新。

  • Maven依賴如下;

????<dependencies>
????????<dependency>
????????????<groupId>org.springframework.boot</groupId>
????????????<artifactId>spring-boot-starter</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>org.springframework.boot</groupId>
????????????<artifactId>spring-boot-starter-web</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>org.springframework.cloud</groupId>
????????????<artifactId>spring-cloud-context</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>org.springframework.boot</groupId>
????????????<artifactId>spring-boot-starter-test</artifactId>
????????????<scope>test</scope>
????????</dependency>
????????<dependency>
????????????<groupId>org.projectlombok</groupId>
????????????<artifactId>lombok</artifactId>
????????????<version>1.18.12</version>
????????</dependency>
????????<dependency>
????????????<groupId>org.slf4j</groupId>
????????????<artifactId>slf4j-api</artifactId>
????????????<version>1.7.5</version>
????????</dependency>
????????<dependency>
????????????<groupId>ch.qos.logback</groupId>
????????????<artifactId>logback-core</artifactId>
????????????<version>1.2.3</version>
????????</dependency>
????????<dependency>
????????????<groupId>ch.qos.logback</groupId>
????????????<artifactId>logback-classic</artifactId>
????????????<version>1.2.3</version>
????????</dependency>

????</dependencies>

????<dependencyManagement>
????????<dependencies>
????????????<dependency>
????????????????<groupId>org.springframework.cloud</groupId>
????????????????<artifactId>spring-cloud-dependencies</artifactId>
????????????????<version>Hoxton.SR7</version>
????????????????<type>pom</type>
????????????????<scope>import</scope>
????????????</dependency>
????????</dependencies>
????</dependencyManagement>
  • 配置信息如下:

monitor.threadpool.executors[0].thread-pool-name=first-monitor-thread-pool
monitor.threadpool.executors[0].core-pool-size=4
monitor.threadpool.executors[0].max-pool-size=8
monitor.threadpool.executors[0].queue-capacity=100

monitor.threadpool.executors[1].thread-pool-name=second-monitor-thread-pool
monitor.threadpool.executors[1].core-pool-size=2
monitor.threadpool.executors[1].max-pool-size=4
monitor.threadpool.executors[1].queue-capacity=40
????
/**
?*?線程池配置
?*
?*?@author?wangtongzhou?
?*?@since?2022-03-11?21:41
?*/
@Data
public?class?ThreadPoolProperties?{
????/**
?????*?線程池名稱
?????*/
????private?String?threadPoolName;
?????*?核心線程數(shù)
????private?Integer?corePoolSize?=?Runtime.getRuntime().availableProcessors();
?????*?最大線程數(shù)
????private?Integer?maxPoolSize;
?????*?隊(duì)列最大數(shù)量
????private?Integer?queueCapacity;
?????*?拒絕策略
????private?String?rejectedExecutionType?=?"AbortPolicy";
?????*?空閑線程存活時間
????private?Long?keepAliveTime?=?1L;
?????*?空閑線程存活時間單位
????private?TimeUnit?unit?=?TimeUnit.MILLISECONDS;
}
?*?動態(tài)刷新線程池配置
?*?@since?2022-03-13?14:09
@ConfigurationProperties(prefix?=?"monitor.threadpool")
@Component
public?class?DynamicThreadPoolProperties?{
????private?List<ThreadPoolProperties>?executors;
  • 自定可修改阻塞隊(duì)列大小的方式如下:

/**
?*?可重新設(shè)定隊(duì)列大小的阻塞隊(duì)列
?*
?*?@author?wangtongzhou?
?*?@since?2022-03-13?11:54
?*/
public?class?ResizableCapacityLinkedBlockingQueue<E>?extends?AbstractQueue<E>
????????implements?BlockingDeque<E>,?java.io.Serializable?{
????/*
?????*?Implemented?as?a?simple?doubly-linked?list?protected?by?a
?????*?single?lock?and?using?conditions?to?manage?blocking.
?????*
?????*?To?implement?weakly?consistent?iterators,?it?appears?we?need?to
?????*?keep?all?Nodes?GC-reachable?from?a?predecessor?dequeued?Node.
?????*?That?would?cause?two?problems:
?????*?-?allow?a?rogue?Iterator?to?cause?unbounded?memory?retention
?????*?-?cause?cross-generational?linking?of?old?Nodes?to?new?Nodes?if
?????*???a?Node?was?tenured?while?live,?which?generational?GCs?have?a
?????*???hard?time?dealing?with,?causing?repeated?major?collections.
?????*?However,?only?non-deleted?Nodes?need?to?be?reachable?from
?????*?dequeued?Nodes,?and?reachability?does?not?necessarily?have?to
?????*?be?of?the?kind?understood?by?the?GC.??We?use?the?trick?of
?????*?linking?a?Node?that?has?just?been?dequeued?to?itself.??Such?a
?????*?self-link?implicitly?means?to?jump?to?"first"?(for?next?links)
?????*?or?"last"?(for?prev?links).
?????*/

????/*
?????*?We?have?"diamond"?multiple?interface/abstract?class?inheritance
?????*?here,?and?that?introduces?ambiguities.?Often?we?want?the
?????*?BlockingDeque?javadoc?combined?with?the?AbstractQueue
?????*?implementation,?so?a?lot?of?method?specs?are?duplicated?here.
?????*/

????private?static?final?long?serialVersionUID?=?-387911632671998426L;

????/**
?????*?Doubly-linked?list?node?class
?????*/
????static?final?class?Node<E>?{
????????/**
?????????*?The?item,?or?null?if?this?node?has?been?removed.
?????????*/
????????E?item;

????????/**
?????????*?One?of:
?????????*?-?the?real?predecessor?Node
?????????*?-?this?Node,?meaning?the?predecessor?is?tail
?????????*?-?null,?meaning?there?is?no?predecessor
?????????*/
????????Node<E>?prev;

????????/**
?????????*?One?of:
?????????*?-?the?real?successor?Node
?????????*?-?this?Node,?meaning?the?successor?is?head
?????????*?-?null,?meaning?there?is?no?successor
?????????*/
????????Node<E>?next;

????????Node(E?x)?{
????????????item?=?x;
????????}
????}

????/**
?????*?Pointer?to?first?node.
?????*?Invariant:?(first?==?null?&&?last?==?null)?||
?????*?(first.prev?==?null?&&?first.item?!=?null)
?????*/
????transient?Node<E>?first;

????/**
?????*?Pointer?to?last?node.
?????*?Invariant:?(first?==?null?&&?last?==?null)?||
?????*?(last.next?==?null?&&?last.item?!=?null)
?????*/
????transient?Node<E>?last;

????/**
?????*?Number?of?items?in?the?deque
?????*/
????private?transient?int?count;

????/**
?????*?Maximum?number?of?items?in?the?deque
?????*/
????private?volatile?int?capacity;

????public?int?getCapacity()?{
????????return?capacity;
????}

????public?void?setCapacity(int?capacity)?{
????????this.capacity?=?capacity;
????}

????/**
?????*?Main?lock?guarding?all?access
?????*/
????final?ReentrantLock?lock?=?new?ReentrantLock();

????/**
?????*?Condition?for?waiting?takes
?????*/
????private?final?Condition?notEmpty?=?lock.newCondition();

????/**
?????*?Condition?for?waiting?puts
?????*/
????private?final?Condition?notFull?=?lock.newCondition();

????/**
?????*?Creates?a?{@code?ResizableCapacityLinkedBlockIngQueue}?with?a?capacity?of
?????*?{@link?Integer#MAX_VALUE}.
?????*/
????public?ResizableCapacityLinkedBlockingQueue()?{
????????this(Integer.MAX_VALUE);
????}

????/**
?????*?Creates?a?{@code?ResizableCapacityLinkedBlockIngQueue}?with?the?given?(fixed)?capacity.
?????*
?????*?@param?capacity?the?capacity?of?this?deque
?????*?@throws?IllegalArgumentException?if?{@code?capacity}?is?less?than?1
?????*/
????public?ResizableCapacityLinkedBlockingQueue(int?capacity)?{
????????if?(capacity?<=?0)?{
????????????throw?new?IllegalArgumentException();
????????}
????????this.capacity?=?capacity;
????}

????/**
?????*?Creates?a?{@code?ResizableCapacityLinkedBlockIngQueue}?with?a?capacity?of
?????*?{@link?Integer#MAX_VALUE},?initially?containing?the?elements?of
?????*?the?given?collection,?added?in?traversal?order?of?the
?????*?collection's?iterator.
?????*
?????*?@param?c?the?collection?of?elements?to?initially?contain
?????*?@throws?NullPointerException?if?the?specified?collection?or?any
?????*??????????????????????????????of?its?elements?are?null
?????*/
????public?ResizableCapacityLinkedBlockingQueue(Collection<??extends?E>?c)?{
????????this(Integer.MAX_VALUE);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();?//?Never?contended,?but?necessary?for?visibility
????????try?{
????????????for?(E?e?:?c)?{
????????????????if?(e?==?null)?{
????????????????????throw?new?NullPointerException();
????????????????}
????????????????if?(!linkLast(new?Node<E>(e)))?{
????????????????????throw?new?IllegalStateException("Deque?full");
????????????????}
????????????}
????????}?finally?{
????????????lock.unlock();
????????}
????}


????//?Basic?linking?and?unlinking?operations,?called?only?while?holding?lock

????/**
?????*?Links?node?as?first?element,?or?returns?false?if?full.
?????*/
????private?boolean?linkFirst(Node<E>?node)?{
????????//?assert?lock.isHeldByCurrentThread();
????????if?(count?>=?capacity)?{
????????????return?false;
????????}
????????Node<E>?f?=?first;
????????node.next?=?f;
????????first?=?node;
????????if?(last?==?null)?{
????????????last?=?node;
????????}?else?{
????????????f.prev?=?node;
????????}
????????++count;
????????notEmpty.signal();
????????return?true;
????}

????/**
?????*?Links?node?as?last?element,?or?returns?false?if?full.
?????*/
????private?boolean?linkLast(Node<E>?node)?{
????????//?assert?lock.isHeldByCurrentThread();
????????if?(count?>=?capacity)?{
????????????return?false;
????????}
????????Node<E>?l?=?last;
????????node.prev?=?l;
????????last?=?node;
????????if?(first?==?null)?{
????????????first?=?node;
????????}?else?{
????????????l.next?=?node;
????????}
????????++count;
????????notEmpty.signal();
????????return?true;
????}

????/**
?????*?Removes?and?returns?first?element,?or?null?if?empty.
?????*/
????private?E?unlinkFirst()?{
????????//?assert?lock.isHeldByCurrentThread();
????????Node<E>?f?=?first;
????????if?(f?==?null)?{
????????????return?null;
????????}
????????Node<E>?n?=?f.next;
????????E?item?=?f.item;
????????f.item?=?null;
????????f.next?=?f;?//?help?GC
????????first?=?n;
????????if?(n?==?null)?{
????????????last?=?null;
????????}?else?{
????????????n.prev?=?null;
????????}
????????--count;
????????notFull.signal();
????????return?item;
????}

????/**
?????*?Removes?and?returns?last?element,?or?null?if?empty.
?????*/
????private?E?unlinkLast()?{
????????//?assert?lock.isHeldByCurrentThread();
????????Node<E>?l?=?last;
????????if?(l?==?null)?{
????????????return?null;
????????}
????????Node<E>?p?=?l.prev;
????????E?item?=?l.item;
????????l.item?=?null;
????????l.prev?=?l;?//?help?GC
????????last?=?p;
????????if?(p?==?null)?{
????????????first?=?null;
????????}?else?{
????????????p.next?=?null;
????????}
????????--count;
????????notFull.signal();
????????return?item;
????}

????/**
?????*?Unlinks?x.
?????*/
????void?unlink(Node<E>?x)?{
????????//?assert?lock.isHeldByCurrentThread();
????????Node<E>?p?=?x.prev;
????????Node<E>?n?=?x.next;
????????if?(p?==?null)?{
????????????unlinkFirst();
????????}?else?if?(n?==?null)?{
????????????unlinkLast();
????????}?else?{
????????????p.next?=?n;
????????????n.prev?=?p;
????????????x.item?=?null;
????????????//?Don't?mess?with?x's?links.??They?may?still?be?in?use?by
????????????//?an?iterator.
????????????--count;
????????????notFull.signal();
????????}
????}

????//?BlockingDeque?methods

????/**
?????*?@throws?IllegalStateException?if?this?deque?is?full
?????*?@throws?NullPointerException??{@inheritDoc}
?????*/
????@Override
????public?void?addFirst(E?e)?{
????????if?(!offerFirst(e))?{
????????????throw?new?IllegalStateException("Deque?full");
????????}
????}

????/**
?????*?@throws?IllegalStateException?if?this?deque?is?full
?????*?@throws?NullPointerException??{@inheritDoc}
?????*/
????@Override
????public?void?addLast(E?e)?{
????????if?(!offerLast(e))?{
????????????throw?new?IllegalStateException("Deque?full");
????????}
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*/
????@Override
????public?boolean?offerFirst(E?e)?{
????????if?(e?==?null)?{
????????????throw?new?NullPointerException();
????????}
????????Node<E>?node?=?new?Node<E>(e);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?linkFirst(node);
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*/
????@Override
????public?boolean?offerLast(E?e)?{
????????if?(e?==?null)?throw?new?NullPointerException();
????????Node<E>?node?=?new?Node<E>(e);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?linkLast(node);
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*?@throws?InterruptedException?{@inheritDoc}
?????*/
????@Override
????public?void?putFirst(E?e)?throws?InterruptedException?{
????????if?(e?==?null)?{
????????????throw?new?NullPointerException();
????????}
????????Node<E>?node?=?new?Node<E>(e);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????while?(!linkFirst(node))?{
????????????????notFull.await();
????????????}
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*?@throws?InterruptedException?{@inheritDoc}
?????*/
????@Override
????public?void?putLast(E?e)?throws?InterruptedException?{
????????if?(e?==?null)?{
????????????throw?new?NullPointerException();
????????}
????????Node<E>?node?=?new?Node<E>(e);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????while?(!linkLast(node))?{
????????????????notFull.await();
????????????}
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*?@throws?InterruptedException?{@inheritDoc}
?????*/
????@Override
????public?boolean?offerFirst(E?e,?long?timeout,?TimeUnit?unit)
????????????throws?InterruptedException?{
????????if?(e?==?null)?{
????????????throw?new?NullPointerException();
????????}
????????Node<E>?node?=?new?Node<E>(e);
????????long?nanos?=?unit.toNanos(timeout);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lockInterruptibly();
????????try?{
????????????while?(!linkFirst(node))?{
????????????????if?(nanos?<=?0)?{
????????????????????return?false;
????????????????}
????????????????nanos?=?notFull.awaitNanos(nanos);
????????????}
????????????return?true;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*?@throws?InterruptedException?{@inheritDoc}
?????*/
????@Override
????public?boolean?offerLast(E?e,?long?timeout,?TimeUnit?unit)
????????????throws?InterruptedException?{
????????if?(e?==?null)?throw?new?NullPointerException();
????????Node<E>?node?=?new?Node<E>(e);
????????long?nanos?=?unit.toNanos(timeout);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lockInterruptibly();
????????try?{
????????????while?(!linkLast(node))?{
????????????????if?(nanos?<=?0)?{
????????????????????return?false;
????????????????}
????????????????nanos?=?notFull.awaitNanos(nanos);
????????????}
????????????return?true;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?NoSuchElementException?{@inheritDoc}
?????*/
????@Override
????public?E?removeFirst()?{
????????E?x?=?pollFirst();
????????if?(x?==?null)?{
????????????throw?new?NoSuchElementException();
????????}
????????return?x;
????}

????/**
?????*?@throws?NoSuchElementException?{@inheritDoc}
?????*/
????@Override
????public?E?removeLast()?{
????????E?x?=?pollLast();
????????if?(x?==?null)?{
????????????throw?new?NoSuchElementException();
????????}
????????return?x;
????}

????@Override
????public?E?pollFirst()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?unlinkFirst();
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?E?pollLast()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?unlinkLast();
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?E?takeFirst()?throws?InterruptedException?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????E?x;
????????????while?((x?=?unlinkFirst())?==?null)?{
????????????????notEmpty.await();
????????????}
????????????return?x;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?E?takeLast()?throws?InterruptedException?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????E?x;
????????????while?((x?=?unlinkLast())?==?null)?{
????????????????notEmpty.await();
????????????}
????????????return?x;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?E?pollFirst(long?timeout,?TimeUnit?unit)
????????????throws?InterruptedException?{
????????long?nanos?=?unit.toNanos(timeout);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lockInterruptibly();
????????try?{
????????????E?x;
????????????while?((x?=?unlinkFirst())?==?null)?{
????????????????if?(nanos?<=?0)?{
????????????????????return?null;
????????????????}
????????????????nanos?=?notEmpty.awaitNanos(nanos);
????????????}
????????????return?x;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?E?pollLast(long?timeout,?TimeUnit?unit)
????????????throws?InterruptedException?{
????????long?nanos?=?unit.toNanos(timeout);
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lockInterruptibly();
????????try?{
????????????E?x;
????????????while?((x?=?unlinkLast())?==?null)?{
????????????????if?(nanos?<=?0)?{
????????????????????return?null;
????????????????}
????????????????nanos?=?notEmpty.awaitNanos(nanos);
????????????}
????????????return?x;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?NoSuchElementException?{@inheritDoc}
?????*/
????@Override
????public?E?getFirst()?{
????????E?x?=?peekFirst();
????????if?(x?==?null)?{
????????????throw?new?NoSuchElementException();
????????}
????????return?x;
????}

????/**
?????*?@throws?NoSuchElementException?{@inheritDoc}
?????*/
????@Override
????public?E?getLast()?{
????????E?x?=?peekLast();
????????if?(x?==?null)?{
????????????throw?new?NoSuchElementException();
????????}
????????return?x;
????}

????@Override
????public?E?peekFirst()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?(first?==?null)???null?:?first.item;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?E?peekLast()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?(last?==?null)???null?:?last.item;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?boolean?removeFirstOccurrence(Object?o)?{
????????if?(o?==?null)?{
????????????return?false;
????????}
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????for?(Node<E>?p?=?first;?p?!=?null;?p?=?p.next)?{
????????????????if?(o.equals(p.item))?{
????????????????????unlink(p);
????????????????????return?true;
????????????????}
????????????}
????????????return?false;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?boolean?removeLastOccurrence(Object?o)?{
????????if?(o?==?null)?{
????????????return?false;
????????}
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????for?(Node<E>?p?=?last;?p?!=?null;?p?=?p.prev)?{
????????????????if?(o.equals(p.item))?{
????????????????????unlink(p);
????????????????????return?true;
????????????????}
????????????}
????????????return?false;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????//?BlockingQueue?methods

????/**
?????*?Inserts?the?specified?element?at?the?end?of?this?deque?unless?it?would
?????*?violate?capacity?restrictions.??When?using?a?capacity-restricted?deque,
?????*?it?is?generally?preferable?to?use?method?{@link?#offer(Object)?offer}.
?????*
?????*?<p>This?method?is?equivalent?to?{@link?#addLast}.
?????*
?????*?@throws?IllegalStateException?if?this?deque?is?full
?????*?@throws?NullPointerException??if?the?specified?element?is?null
?????*/
????@Override
????public?boolean?add(E?e)?{
????????addLast(e);
????????return?true;
????}

????/**
?????*?@throws?NullPointerException?if?the?specified?element?is?null
?????*/
????@Override
????public?boolean?offer(E?e)?{
????????return?offerLast(e);
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*?@throws?InterruptedException?{@inheritDoc}
?????*/
????@Override
????public?void?put(E?e)?throws?InterruptedException?{
????????putLast(e);
????}

????/**
?????*?@throws?NullPointerException?{@inheritDoc}
?????*?@throws?InterruptedException?{@inheritDoc}
?????*/
????@Override
????public?boolean?offer(E?e,?long?timeout,?TimeUnit?unit)
????????????throws?InterruptedException?{
????????return?offerLast(e,?timeout,?unit);
????}

????/**
?????*?Retrieves?and?removes?the?head?of?the?queue?represented?by?this?deque.
?????*?This?method?differs?from?{@link?#poll?poll}?only?in?that?it?throws?an
?????*?exception?if?this?deque?is?empty.
?????*
?????*?<p>This?method?is?equivalent?to?{@link?#removeFirst()?removeFirst}.
?????*
?????*?@return?the?head?of?the?queue?represented?by?this?deque
?????*?@throws?NoSuchElementException?if?this?deque?is?empty
?????*/
????@Override
????public?E?remove()?{
????????return?removeFirst();
????}

????@Override
????public?E?poll()?{
????????return?pollFirst();
????}

????@Override
????public?E?take()?throws?InterruptedException?{
????????return?takeFirst();
????}

????@Override
????public?E?poll(long?timeout,?TimeUnit?unit)?throws?InterruptedException?{
????????return?pollFirst(timeout,?unit);
????}

????/**
?????*?Retrieves,?but?does?not?remove,?the?head?of?the?queue?represented?by
?????*?this?deque.??This?method?differs?from?{@link?#peek?peek}?only?in?that
?????*?it?throws?an?exception?if?this?deque?is?empty.
?????*
?????*?<p>This?method?is?equivalent?to?{@link?#getFirst()?getFirst}.
?????*
?????*?@return?the?head?of?the?queue?represented?by?this?deque
?????*?@throws?NoSuchElementException?if?this?deque?is?empty
?????*/
????@Override
????public?E?element()?{
????????return?getFirst();
????}

????@Override
????public?E?peek()?{
????????return?peekFirst();
????}

????/**
?????*?Returns?the?number?of?additional?elements?that?this?deque?can?ideally
?????*?(in?the?absence?of?memory?or?resource?constraints)?accept?without
?????*?blocking.?This?is?always?equal?to?the?initial?capacity?of?this?deque
?????*?less?the?current?{@code?size}?of?this?deque.
?????*
?????*?<p>Note?that?you?<em>cannot</em>?always?tell?if?an?attempt?to?insert
?????*?an?element?will?succeed?by?inspecting?{@code?remainingCapacity}
?????*?because?it?may?be?the?case?that?another?thread?is?about?to
?????*?insert?or?remove?an?element.
?????*/
????@Override
????public?int?remainingCapacity()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?capacity?-?count;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?@throws?UnsupportedOperationException?{@inheritDoc}
?????*?@throws?ClassCastException????????????{@inheritDoc}
?????*?@throws?NullPointerException??????????{@inheritDoc}
?????*?@throws?IllegalArgumentException??????{@inheritDoc}
?????*/
????@Override
????public?int?drainTo(Collection<??super?E>?c)?{
????????return?drainTo(c,?Integer.MAX_VALUE);
????}

????/**
?????*?@throws?UnsupportedOperationException?{@inheritDoc}
?????*?@throws?ClassCastException????????????{@inheritDoc}
?????*?@throws?NullPointerException??????????{@inheritDoc}
?????*?@throws?IllegalArgumentException??????{@inheritDoc}
?????*/
????@Override
????public?int?drainTo(Collection<??super?E>?c,?int?maxElements)?{
????????if?(c?==?null)?{
????????????throw?new?NullPointerException();
????????}
????????if?(c?==?this)?{
????????????throw?new?IllegalArgumentException();
????????}
????????if?(maxElements?<=?0)?{
????????????return?0;
????????}
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????int?n?=?Math.min(maxElements,?count);
????????????for?(int?i?=?0;?i?<?n;?i++)?{
????????????????c.add(first.item);???//?In?this?order,?in?case?add()?throws.
????????????????unlinkFirst();
????????????}
????????????return?n;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????//?Stack?methods

????/**
?????*?@throws?IllegalStateException?if?this?deque?is?full
?????*?@throws?NullPointerException??{@inheritDoc}
?????*/
????@Override
????public?void?push(E?e)?{
????????addFirst(e);
????}

????/**
?????*?@throws?NoSuchElementException?{@inheritDoc}
?????*/
????@Override
????public?E?pop()?{
????????return?removeFirst();
????}

????//?Collection?methods

????/**
?????*?Removes?the?first?occurrence?of?the?specified?element?from?this?deque.
?????*?If?the?deque?does?not?contain?the?element,?it?is?unchanged.
?????*?More?formally,?removes?the?first?element?{@code?e}?such?that
?????*?{@code?o.equals(e)}?(if?such?an?element?exists).
?????*?Returns?{@code?true}?if?this?deque?contained?the?specified?element
?????*?(or?equivalently,?if?this?deque?changed?as?a?result?of?the?call).
?????*
?????*?<p>This?method?is?equivalent?to
?????*?{@link?#removeFirstOccurrence(Object)?removeFirstOccurrence}.
?????*
?????*?@param?o?element?to?be?removed?from?this?deque,?if?present
?????*?@return?{@code?true}?if?this?deque?changed?as?a?result?of?the?call
?????*/
????@Override
????public?boolean?remove(Object?o)?{
????????return?removeFirstOccurrence(o);
????}

????/**
?????*?Returns?the?number?of?elements?in?this?deque.
?????*
?????*?@return?the?number?of?elements?in?this?deque
?????*/
????@Override
????public?int?size()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????return?count;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?Returns?{@code?true}?if?this?deque?contains?the?specified?element.
?????*?More?formally,?returns?{@code?true}?if?and?only?if?this?deque?contains
?????*?at?least?one?element?{@code?e}?such?that?{@code?o.equals(e)}.
?????*
?????*?@param?o?object?to?be?checked?for?containment?in?this?deque
?????*?@return?{@code?true}?if?this?deque?contains?the?specified?element
?????*/
????@Override
????public?boolean?contains(Object?o)?{
????????if?(o?==?null)?{
????????????return?false;
????????}
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????for?(Node<E>?p?=?first;?p?!=?null;?p?=?p.next)?{
????????????????if?(o.equals(p.item))?{
????????????????????return?true;
????????????????}
????????????}
????????????return?false;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/*
?????*?TODO:?Add?support?for?more?efficient?bulk?operations.
?????*
?????*?We?don't?want?to?acquire?the?lock?for?every?iteration,?but?we
?????*?also?want?other?threads?a?chance?to?interact?with?the
?????*?collection,?especially?when?count?is?close?to?capacity.
?????*/

//?????/**
//??????*?Adds?all?of?the?elements?in?the?specified?collection?to?this
//??????*?queue.??Attempts?to?addAll?of?a?queue?to?itself?result?in
//??????*?{@code?IllegalArgumentException}.?Further,?the?behavior?of
//??????*?this?operation?is?undefined?if?the?specified?collection?is
//??????*?modified?while?the?operation?is?in?progress.
//??????*
//??????*?@param?c?collection?containing?elements?to?be?added?to?this?queue
//??????*?@return?{@code?true}?if?this?queue?changed?as?a?result?of?the?call
//??????*?@throws?ClassCastException????????????{@inheritDoc}
//??????*?@throws?NullPointerException??????????{@inheritDoc}
//??????*?@throws?IllegalArgumentException??????{@inheritDoc}
//??????*?@throws?IllegalStateException?if?this?deque?is?full
//??????*?@see?#add(Object)
//??????*/
//?????public?boolean?addAll(Collection<??extends?E>?c)?{
//?????????if?(c?==?null)
//?????????????throw?new?NullPointerException();
//?????????if?(c?==?this)
//?????????????throw?new?IllegalArgumentException();
//?????????final?ReentrantLock?lock?=?this.lock;
//?????????lock.lock();
//?????????try?{
//?????????????boolean?modified?=?false;
//?????????????for?(E?e?:?c)
//?????????????????if?(linkLast(e))
//?????????????????????modified?=?true;
//?????????????return?modified;
//?????????}?finally?{
//?????????????lock.unlock();
//?????????}
//?????}

????/**
?????*?Returns?an?array?containing?all?of?the?elements?in?this?deque,?in
?????*?proper?sequence?(from?first?to?last?element).
?????*
?????*?<p>The?returned?array?will?be?"safe"?in?that?no?references?to?it?are
?????*?maintained?by?this?deque.??(In?other?words,?this?method?must?allocate
?????*?a?new?array).??The?caller?is?thus?free?to?modify?the?returned?array.
?????*
?????*?<p>This?method?acts?as?bridge?between?array-based?and?collection-based
?????*?APIs.
?????*
?????*?@return?an?array?containing?all?of?the?elements?in?this?deque
?????*/
????@Override
????@SuppressWarnings("unchecked")
????public?Object[]?toArray()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????Object[]?a?=?new?Object[count];
????????????int?k?=?0;
????????????for?(Node<E>?p?=?first;?p?!=?null;?p?=?p.next)?{
????????????????a[k++]?=?p.item;
????????????}
????????????return?a;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?Returns?an?array?containing?all?of?the?elements?in?this?deque,?in
?????*?proper?sequence;?the?runtime?type?of?the?returned?array?is?that?of
?????*?the?specified?array.??If?the?deque?fits?in?the?specified?array,?it
?????*?is?returned?therein.??Otherwise,?a?new?array?is?allocated?with?the
?????*?runtime?type?of?the?specified?array?and?the?size?of?this?deque.
?????*
?????*?<p>If?this?deque?fits?in?the?specified?array?with?room?to?spare
?????*?(i.e.,?the?array?has?more?elements?than?this?deque),?the?element?in
?????*?the?array?immediately?following?the?end?of?the?deque?is?set?to
?????*?{@code?null}.
?????*
?????*?<p>Like?the?{@link?#toArray()}?method,?this?method?acts?as?bridge?between
?????*?array-based?and?collection-based?APIs.??Further,?this?method?allows
?????*?precise?control?over?the?runtime?type?of?the?output?array,?and?may,
?????*?under?certain?circumstances,?be?used?to?save?allocation?costs.
?????*
?????*?<p>Suppose?{@code?x}?is?a?deque?known?to?contain?only?strings.
?????*?The?following?code?can?be?used?to?dump?the?deque?into?a?newly
?????*?allocated?array?of?{@code?String}:
?????*
?????*?<pre>?{@code?String[]?y?=?x.toArray(new?String[0]);}</pre>
?????*?<p>
?????*?Note?that?{@code?toArray(new?Object[0])}?is?identical?in?function?to
?????*?{@code?toArray()}.
?????*
?????*?@param?a?the?array?into?which?the?elements?of?the?deque?are?to
?????*??????????be?stored,?if?it?is?big?enough;?otherwise,?a?new?array?of?the
?????*??????????same?runtime?type?is?allocated?for?this?purpose
?????*?@return?an?array?containing?all?of?the?elements?in?this?deque
?????*?@throws?ArrayStoreException??if?the?runtime?type?of?the?specified?array
?????*??????????????????????????????is?not?a?supertype?of?the?runtime?type?of?every?element?in
?????*??????????????????????????????this?deque
?????*?@throws?NullPointerException?if?the?specified?array?is?null
?????*/
????@Override
????@SuppressWarnings("unchecked")
????public?<T>?T[]?toArray(T[]?a)?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????if?(a.length?<?count)?{
????????????????a?=?(T[])?java.lang.reflect.Array.newInstance
????????????????????????(a.getClass().getComponentType(),?count);
????????????}
????????????int?k?=?0;
????????????for?(Node<E>?p?=?first;?p?!=?null;?p?=?p.next)?{
????????????????a[k++]?=?(T)?p.item;
????????????}
????????????if?(a.length?>?k)?{
????????????????a[k]?=?null;
????????????}
????????????return?a;
????????}?finally?{
????????????lock.unlock();
????????}
????}

????@Override
????public?String?toString()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????Node<E>?p?=?first;
????????????if?(p?==?null)?{
????????????????return?"[]";
????????????}
????????????StringBuilder?sb?=?new?StringBuilder();
????????????sb.append('[');
????????????for?(;?;?)?{
????????????????E?e?=?p.item;
????????????????sb.append(e?==?this???"(this?Collection)"?:?e);
????????????????p?=?p.next;
????????????????if?(p?==?null)?{
????????????????????return?sb.append(']').toString();
????????????????}
????????????????sb.append(',').append('?');
????????????}
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?Atomically?removes?all?of?the?elements?from?this?deque.
?????*?The?deque?will?be?empty?after?this?call?returns.
?????*/
????@Override
????public?void?clear()?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????for?(Node<E>?f?=?first;?f?!=?null;?)?{
????????????????f.item?=?null;
????????????????Node<E>?n?=?f.next;
????????????????f.prev?=?null;
????????????????f.next?=?null;
????????????????f?=?n;
????????????}
????????????first?=?last?=?null;
????????????count?=?0;
????????????notFull.signalAll();
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?Returns?an?iterator?over?the?elements?in?this?deque?in?proper?sequence.
?????*?The?elements?will?be?returned?in?order?from?first?(head)?to?last?(tail).
?????*
?????*?<p>The?returned?iterator?is
?????*?<a?href="package-summary.html#Weakly" rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ><i>weakly?consistent</i></a>.
?????*
?????*?@return?an?iterator?over?the?elements?in?this?deque?in?proper?sequence
?????*/
????@Override
????public?Iterator<E>?iterator()?{
????????return?new?Itr();
????}

????/**
?????*?Returns?an?iterator?over?the?elements?in?this?deque?in?reverse
?????*?sequential?order.??The?elements?will?be?returned?in?order?from
?????*?last?(tail)?to?first?(head).
?????*
?????*?<p>The?returned?iterator?is
?????*?<a?href="package-summary.html#Weakly" rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ><i>weakly?consistent</i></a>.
?????*
?????*?@return?an?iterator?over?the?elements?in?this?deque?in?reverse?order
?????*/
????@Override
????public?Iterator<E>?descendingIterator()?{
????????return?new?DescendingItr();
????}

????/**
?????*?Base?class?for?Iterators?for?ResizableCapacityLinkedBlockIngQueue
?????*/
????private?abstract?class?AbstractItr?implements?Iterator<E>?{
????????/**
?????????*?The?next?node?to?return?in?next()
?????????*/
????????Node<E>?next;

????????/**
?????????*?nextItem?holds?on?to?item?fields?because?once?we?claim?that
?????????*?an?element?exists?in?hasNext(),?we?must?return?item?read
?????????*?under?lock?(in?advance())?even?if?it?was?in?the?process?of
?????????*?being?removed?when?hasNext()?was?called.
?????????*/
????????E?nextItem;

????????/**
?????????*?Node?returned?by?most?recent?call?to?next.?Needed?by?remove.
?????????*?Reset?to?null?if?this?element?is?deleted?by?a?call?to?remove.
?????????*/
????????private?Node<E>?lastRet;

????????abstract?Node<E>?firstNode();

????????abstract?Node<E>?nextNode(Node<E>?n);

????????AbstractItr()?{
????????????//?set?to?initial?position
????????????final?ReentrantLock?lock?=?ResizableCapacityLinkedBlockingQueue.this.lock;
????????????lock.lock();
????????????try?{
????????????????next?=?firstNode();
????????????????nextItem?=?(next?==?null)???null?:?next.item;
????????????}?finally?{
????????????????lock.unlock();
????????????}
????????}

????????/**
?????????*?Returns?the?successor?node?of?the?given?non-null,?but
?????????*?possibly?previously?deleted,?node.
?????????*/
????????private?Node<E>?succ(Node<E>?n)?{
????????????//?Chains?of?deleted?nodes?ending?in?null?or?self-links
????????????//?are?possible?if?multiple?interior?nodes?are?removed.
????????????for?(;?;?)?{
????????????????Node<E>?s?=?nextNode(n);
????????????????if?(s?==?null)?{
????????????????????return?null;
????????????????}?else?if?(s.item?!=?null)?{
????????????????????return?s;
????????????????}?else?if?(s?==?n)?{
????????????????????return?firstNode();
????????????????}?else?{
????????????????????n?=?s;
????????????????}
????????????}
????????}

????????/**
?????????*?Advances?next.
?????????*/
????????void?advance()?{
????????????final?ReentrantLock?lock?=?ResizableCapacityLinkedBlockingQueue.this.lock;
????????????lock.lock();
????????????try?{
????????????????//?assert?next?!=?null;
????????????????next?=?succ(next);
????????????????nextItem?=?(next?==?null)???null?:?next.item;
????????????}?finally?{
????????????????lock.unlock();
????????????}
????????}

????????@Override
????????public?boolean?hasNext()?{
????????????return?next?!=?null;
????????}

????????@Override
????????public?E?next()?{
????????????if?(next?==?null)?{
????????????????throw?new?NoSuchElementException();
????????????}
????????????lastRet?=?next;
????????????E?x?=?nextItem;
????????????advance();
????????????return?x;
????????}

????????@Override
????????public?void?remove()?{
????????????Node<E>?n?=?lastRet;
????????????if?(n?==?null)?{
????????????????throw?new?IllegalStateException();
????????????}
????????????lastRet?=?null;
????????????final?ReentrantLock?lock?=?ResizableCapacityLinkedBlockingQueue.this.lock;
????????????lock.lock();
????????????try?{
????????????????if?(n.item?!=?null)?{
????????????????????unlink(n);
????????????????}
????????????}?finally?{
????????????????lock.unlock();
????????????}
????????}
????}

????/**
?????*?Forward?iterator
?????*/
????private?class?Itr?extends?AbstractItr?{
????????@Override
????????Node<E>?firstNode()?{
????????????return?first;
????????}

????????@Override
????????Node<E>?nextNode(Node<E>?n)?{
????????????return?n.next;
????????}
????}

????/**
?????*?Descending?iterator
?????*/
????private?class?DescendingItr?extends?AbstractItr?{
????????@Override
????????Node<E>?firstNode()?{
????????????return?last;
????????}

????????@Override
????????Node<E>?nextNode(Node<E>?n)?{
????????????return?n.prev;
????????}
????}

????/**
?????*?A?customized?variant?of?Spliterators.IteratorSpliterator
?????*/
????static?final?class?LBDSpliterator<E>?implements?Spliterator<E>?{
????????static?final?int?MAX_BATCH?=?1?<<?25;??//?max?batch?array?size;
????????final?ResizableCapacityLinkedBlockingQueue<E>?queue;
????????Node<E>?current;????//?current?node;?null?until?initialized
????????int?batch;??????????//?batch?size?for?splits
????????boolean?exhausted;??//?true?when?no?more?nodes
????????long?est;???????????//?size?estimate

????????LBDSpliterator(ResizableCapacityLinkedBlockingQueue<E>?queue)?{
????????????this.queue?=?queue;
????????????this.est?=?queue.size();
????????}

????????@Override
????????public?long?estimateSize()?{
????????????return?est;
????????}

????????@Override
????????public?Spliterator<E>?trySplit()?{
????????????Node<E>?h;
????????????final?ResizableCapacityLinkedBlockingQueue<E>?q?=?this.queue;
????????????int?b?=?batch;
????????????int?n?=?(b?<=?0)???1?:?(b?>=?MAX_BATCH)???MAX_BATCH?:?b?+?1;
????????????if?(!exhausted?&&
????????????????????((h?=?current)?!=?null?||?(h?=?q.first)?!=?null)?&&
????????????????????h.next?!=?null)?{
????????????????Object[]?a?=?new?Object[n];
????????????????final?ReentrantLock?lock?=?q.lock;
????????????????int?i?=?0;
????????????????Node<E>?p?=?current;
????????????????lock.lock();
????????????????try?{
????????????????????if?(p?!=?null?||?(p?=?q.first)?!=?null)?{
????????????????????????do?{
????????????????????????????if?((a[i]?=?p.item)?!=?null)?{
????????????????????????????????++i;
????????????????????????????}
????????????????????????}?while?((p?=?p.next)?!=?null?&&?i?<?n);
????????????????????}
????????????????}?finally?{
????????????????????lock.unlock();
????????????????}
????????????????if?((current?=?p)?==?null)?{
????????????????????est?=?0L;
????????????????????exhausted?=?true;
????????????????}?else?if?((est?-=?i)?<?0L)?{
????????????????????est?=?0L;
????????????????}
????????????????if?(i?>?0)?{
????????????????????batch?=?i;
????????????????????return?Spliterators.spliterator
????????????????????????????(a,?0,?i,?Spliterator.ORDERED?|?Spliterator.NONNULL?|
????????????????????????????????????Spliterator.CONCURRENT);
????????????????}
????????????}
????????????return?null;
????????}

????????@Override
????????public?void?forEachRemaining(Consumer<??super?E>?action)?{
????????????if?(action?==?null)?{
????????????????throw?new?NullPointerException();
????????????}
????????????final?ResizableCapacityLinkedBlockingQueue<E>?q?=?this.queue;
????????????final?ReentrantLock?lock?=?q.lock;
????????????if?(!exhausted)?{
????????????????exhausted?=?true;
????????????????Node<E>?p?=?current;
????????????????do?{
????????????????????E?e?=?null;
????????????????????lock.lock();
????????????????????try?{
????????????????????????if?(p?==?null)?{
????????????????????????????p?=?q.first;
????????????????????????}
????????????????????????while?(p?!=?null)?{
????????????????????????????e?=?p.item;
????????????????????????????p?=?p.next;
????????????????????????????if?(e?!=?null)?{
????????????????????????????????break;
????????????????????????????}
????????????????????????}
????????????????????}?finally?{
????????????????????????lock.unlock();
????????????????????}
????????????????????if?(e?!=?null)?{
????????????????????????action.accept(e);
????????????????????}
????????????????}?while?(p?!=?null);
????????????}
????????}

????????@Override
????????public?boolean?tryAdvance(Consumer<??super?E>?action)?{
????????????if?(action?==?null)?{
????????????????throw?new?NullPointerException();
????????????}
????????????final?ResizableCapacityLinkedBlockingQueue<E>?q?=?this.queue;
????????????final?ReentrantLock?lock?=?q.lock;
????????????if?(!exhausted)?{
????????????????E?e?=?null;
????????????????lock.lock();
????????????????try?{
????????????????????if?(current?==?null)?{
????????????????????????current?=?q.first;
????????????????????}
????????????????????while?(current?!=?null)?{
????????????????????????e?=?current.item;
????????????????????????current?=?current.next;
????????????????????????if?(e?!=?null)?{
????????????????????????????break;
????????????????????????}
????????????????????}
????????????????}?finally?{
????????????????????lock.unlock();
????????????????}
????????????????if?(current?==?null)?{
????????????????????exhausted?=?true;
????????????????}
????????????????if?(e?!=?null)?{
????????????????????action.accept(e);
????????????????????return?true;
????????????????}
????????????}
????????????return?false;
????????}

????????@Override
????????public?int?characteristics()?{
????????????return?Spliterator.ORDERED?|?Spliterator.NONNULL?|
????????????????????Spliterator.CONCURRENT;
????????}
????}

????/**
?????*?Returns?a?{@link?Spliterator}?over?the?elements?in?this?deque.
?????*
?????*?<p>The?returned?spliterator?is
?????*?<a?href="package-summary.html#Weakly" rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ><i>weakly?consistent</i></a>.
?????*
?????*?<p>The?{@code?Spliterator}?reports?{@link?Spliterator#CONCURRENT},
?????*?{@link?Spliterator#ORDERED},?and?{@link?Spliterator#NONNULL}.
?????*
?????*?@return?a?{@code?Spliterator}?over?the?elements?in?this?deque
?????*?@implNote?The?{@code?Spliterator}?implements?{@code?trySplit}?to?permit?limited
?????*?parallelism.
?????*?@since?1.8
?????*/
????@Override
????public?Spliterator<E>?spliterator()?{
????????return?new?LBDSpliterator<E>(this);
????}

????/**
?????*?Saves?this?deque?to?a?stream?(that?is,?serializes?it).
?????*
?????*?@param?s?the?stream
?????*?@throws?java.io.IOException?if?an?I/O?error?occurs
?????*?@serialData?The?capacity?(int),?followed?by?elements?(each?an
?????*?{@code?Object})?in?the?proper?order,?followed?by?a?null
?????*/
????private?void?writeObject(java.io.ObjectOutputStream?s)
????????????throws?java.io.IOException?{
????????final?ReentrantLock?lock?=?this.lock;
????????lock.lock();
????????try?{
????????????//?Write?out?capacity?and?any?hidden?stuff
????????????s.defaultWriteObject();
????????????//?Write?out?all?elements?in?the?proper?order.
????????????for?(Node<E>?p?=?first;?p?!=?null;?p?=?p.next)?{
????????????????s.writeObject(p.item);
????????????}
????????????//?Use?trailing?null?as?sentinel
????????????s.writeObject(null);
????????}?finally?{
????????????lock.unlock();
????????}
????}

????/**
?????*?Reconstitutes?this?deque?from?a?stream?(that?is,?deserializes?it).
?????*
?????*?@param?s?the?stream
?????*?@throws?ClassNotFoundException?if?the?class?of?a?serialized?object
?????*????????????????????????????????could?not?be?found
?????*?@throws?java.io.IOException????if?an?I/O?error?occurs
?????*/
????private?void?readObject(java.io.ObjectInputStream?s)
????????????throws?java.io.IOException,?ClassNotFoundException?{
????????s.defaultReadObject();
????????count?=?0;
????????first?=?null;
????????last?=?null;
????????//?Read?in?all?elements?and?place?in?queue
????????for?(;?;?)?{
????????????@SuppressWarnings("unchecked")
????????????E?item?=?(E)?s.readObject();
????????????if?(item?==?null)?{
????????????????break;
????????????}
????????????add(item);
????????}
????}
}

  • 自定義線程池,增加每個線程處理的耗時,以及平均耗時、最大耗時、最小耗時,以及輸出監(jiān)控日志信息等等;

/**
?*?線程池監(jiān)控類
?*
?*?@author?wangtongzhou?
?*?@since?2022-02-23?07:27
?*/
public?class?ThreadPoolMonitor?extends?ThreadPoolExecutor?{

????private?static?final?Logger?LOGGER?=?LoggerFactory.getLogger(ThreadPoolMonitor.class);

????/**
?????*?默認(rèn)拒絕策略
?????*/
????private?static?final?RejectedExecutionHandler?defaultHandler?=?new?AbortPolicy();

????/**
?????*?線程池名稱,一般以業(yè)務(wù)名稱命名,方便區(qū)分
?????*/
????private?String?poolName;

????/**
?????*?最短執(zhí)行時間
?????*/
????private?Long?minCostTime;

????/**
?????*?最長執(zhí)行時間
?????*/
????private?Long?maxCostTime;
????/**
?????*?總的耗時
?????*/
????private?AtomicLong?totalCostTime?=?new?AtomicLong();

????private?ThreadLocal<Long>?startTimeThreadLocal?=?new?ThreadLocal<>();

????/**
?????*?調(diào)用父類的構(gòu)造方法,并初始化HashMap和線程池名稱
?????*
?????*?@param?corePoolSize????線程池核心線程數(shù)
?????*?@param?maximumPoolSize?線程池最大線程數(shù)
?????*?@param?keepAliveTime???線程的最大空閑時間
?????*?@param?unit????????????空閑時間的單位
?????*?@param?workQueue???????保存被提交任務(wù)的隊(duì)列
?????*?@param?poolName????????線程池名稱
?????*/
????public?ThreadPoolMonitor(int?corePoolSize,?int?maximumPoolSize,?long?keepAliveTime,
?????????????????????????????TimeUnit?unit,?BlockingQueue<Runnable>?workQueue,?String?poolName)?{
????????this(corePoolSize,?maximumPoolSize,?keepAliveTime,?unit,?workQueue,
????????????????Executors.defaultThreadFactory(),?poolName);
????}


????/**
?????*?調(diào)用父類的構(gòu)造方法,并初始化HashMap和線程池名稱
?????*
?????*?@param?corePoolSize????線程池核心線程數(shù)
?????*?@param?maximumPoolSize?線程池最大線程數(shù)
?????*?@param?keepAliveTime???線程的最大空閑時間
?????*?@param?unit????????????空閑時間的單位
?????*?@param?workQueue???????保存被提交任務(wù)的隊(duì)列
?????*?@param
?????*?@param?poolName????????線程池名稱
?????*/
????public?ThreadPoolMonitor(int?corePoolSize,?int?maximumPoolSize,?long?keepAliveTime,
?????????????????????????????TimeUnit?unit,?BlockingQueue<Runnable>?workQueue,?RejectedExecutionHandler?handler,?String?poolName)?{
????????this(corePoolSize,?maximumPoolSize,?keepAliveTime,?unit,?workQueue,
????????????????Executors.defaultThreadFactory(),?handler,?poolName);
????}


????/**
?????*?調(diào)用父類的構(gòu)造方法,并初始化HashMap和線程池名稱
?????*
?????*?@param?corePoolSize????線程池核心線程數(shù)
?????*?@param?maximumPoolSize?線程池最大線程數(shù)
?????*?@param?keepAliveTime???線程的最大空閑時間
?????*?@param?unit????????????空閑時間的單位
?????*?@param?workQueue???????保存被提交任務(wù)的隊(duì)列
?????*?@param?threadFactory???線程工廠
?????*?@param?poolName????????線程池名稱
?????*/
????public?ThreadPoolMonitor(int?corePoolSize,?int?maximumPoolSize,?long?keepAliveTime,
?????????????????????????????TimeUnit?unit,?BlockingQueue<Runnable>?workQueue,
?????????????????????????????ThreadFactory?threadFactory,?String?poolName)?{
????????super(corePoolSize,?maximumPoolSize,?keepAliveTime,?unit,?workQueue,?threadFactory,?defaultHandler);
????????this.poolName?=?poolName;
????}


????/**
?????*?調(diào)用父類的構(gòu)造方法,并初始化HashMap和線程池名稱
?????*
?????*?@param?corePoolSize????線程池核心線程數(shù)
?????*?@param?maximumPoolSize?線程池最大線程數(shù)
?????*?@param?keepAliveTime???線程的最大空閑時間
?????*?@param?unit????????????空閑時間的單位
?????*?@param?workQueue???????保存被提交任務(wù)的隊(duì)列
?????*?@param?threadFactory???線程工廠
?????*?@param?handler?????????拒絕策略
?????*?@param?poolName????????線程池名稱
?????*/
????public?ThreadPoolMonitor(int?corePoolSize,?int?maximumPoolSize,?long?keepAliveTime,
?????????????????????????????TimeUnit?unit,?BlockingQueue<Runnable>?workQueue,
?????????????????????????????ThreadFactory?threadFactory,?RejectedExecutionHandler?handler,?String?poolName)?{
????????super(corePoolSize,?maximumPoolSize,?keepAliveTime,?unit,?workQueue,?threadFactory,?handler);
????????this.poolName?=?poolName;
????}


????/**
?????*?線程池延遲關(guān)閉時(等待線程池里的任務(wù)都執(zhí)行完畢),統(tǒng)計(jì)線程池情況
?????*/
????@Override
????public?void?shutdown()?{
????????//?統(tǒng)計(jì)已執(zhí)行任務(wù)、正在執(zhí)行任務(wù)、未執(zhí)行任務(wù)數(shù)量
????????LOGGER.info("{}?關(guān)閉線程池,?已執(zhí)行任務(wù):?{},?正在執(zhí)行任務(wù):?{},?未執(zhí)行任務(wù)數(shù)量:?{}",
????????????????this.poolName,?this.getCompletedTaskCount(),?this.getActiveCount(),?this.getQueue().size());
????????super.shutdown();
????}

????/**
?????*?線程池立即關(guān)閉時,統(tǒng)計(jì)線程池情況
?????*/
????@Override
????public?List<Runnable>?shutdownNow()?{
????????//?統(tǒng)計(jì)已執(zhí)行任務(wù)、正在執(zhí)行任務(wù)、未執(zhí)行任務(wù)數(shù)量
????????LOGGER.info("{}?立即關(guān)閉線程池,已執(zhí)行任務(wù):?{},?正在執(zhí)行任務(wù):?{},?未執(zhí)行任務(wù)數(shù)量:?{}",
????????????????this.poolName,?this.getCompletedTaskCount(),?this.getActiveCount(),?this.getQueue().size());
????????return?super.shutdownNow();
????}

????/**
?????*?任務(wù)執(zhí)行之前,記錄任務(wù)開始時間
?????*/
????@Override
????protected?void?beforeExecute(Thread?t,?Runnable?r)?{
????????startTimeThreadLocal.set(System.currentTimeMillis());
????}

????/**
?????*?任務(wù)執(zhí)行之后,計(jì)算任務(wù)結(jié)束時間
?????*/
????@Override
????protected?void?afterExecute(Runnable?r,?Throwable?t)?{
????????long?costTime?=?System.currentTimeMillis()?-?startTimeThreadLocal.get();
????????startTimeThreadLocal.remove();
????????maxCostTime?=?maxCostTime?>?costTime???maxCostTime?:?costTime;
????????if?(getCompletedTaskCount()?==?0)?{
????????????minCostTime?=?costTime;
????????}
????????minCostTime?=?minCostTime?<?costTime???minCostTime?:?costTime;
????????totalCostTime.addAndGet(costTime);
????????LOGGER.info("{}-pool-monitor:?"?+
????????????????????????"任務(wù)耗時:?{}?ms,?初始線程數(shù):?{},?核心線程數(shù):?{},?執(zhí)行的任務(wù)數(shù)量:?{},?"?+
????????????????????????"已完成任務(wù)數(shù)量:?{},?任務(wù)總數(shù):?{},?隊(duì)列里緩存的任務(wù)數(shù)量:?{},?池中存在的最大線程數(shù):?{},?"?+
????????????????????????"最大允許的線程數(shù):?{},??線程空閑時間:?{},?線程池是否關(guān)閉:?{},?線程池是否終止:?{}",
????????????????this.poolName,
????????????????costTime,?this.getPoolSize(),?this.getCorePoolSize(),?this.getActiveCount(),
????????????????this.getCompletedTaskCount(),?this.getTaskCount(),?this.getQueue().size(),?this.getLargestPoolSize(),
????????????????this.getMaximumPoolSize(),?this.getKeepAliveTime(TimeUnit.MILLISECONDS),?this.isShutdown(),?this.isTerminated());
????}


????public?Long?getMinCostTime()?{
????????return?minCostTime;
????}

????public?Long?getMaxCostTime()?{
????????return?maxCostTime;
????}

????public?long?getAverageCostTime(){
????????if(getCompletedTaskCount()==0||totalCostTime.get()==0){
????????????return?0;
????????}
????????return?totalCostTime.get()/getCompletedTaskCount();
????}

????/**
?????*?生成線程池所用的線程,改寫了線程池默認(rèn)的線程工廠,傳入線程池名稱,便于問題追蹤
?????*/
????static?class?MonitorThreadFactory?implements?ThreadFactory?{
????????private?static?final?AtomicInteger?poolNumber?=?new?AtomicInteger(1);
????????private?final?ThreadGroup?group;
????????private?final?AtomicInteger?threadNumber?=?new?AtomicInteger(1);
????????private?final?String?namePrefix;

????????/**
?????????*?初始化線程工廠
?????????*
?????????*?@param?poolName?線程池名稱
?????????*/
????????MonitorThreadFactory(String?poolName)?{
????????????SecurityManager?s?=?System.getSecurityManager();
????????????group?=?Objects.nonNull(s)???s.getThreadGroup()?:?Thread.currentThread().getThreadGroup();
????????????namePrefix?=?poolName?+?"-pool-"?+?poolNumber.getAndIncrement()?+?"-thread-";
????????}

????????@Override
????????public?Thread?newThread(Runnable?r)?{
????????????Thread?t?=?new?Thread(group,?r,?namePrefix?+?threadNumber.getAndIncrement(),?0);
????????????if?(t.isDaemon())?{
????????????????t.setDaemon(false);
????????????}
????????????if?(t.getPriority()?!=?Thread.NORM_PRIORITY)?{
????????????????t.setPriority(Thread.NORM_PRIORITY);
????????????}
????????????return?t;
????????}
????}
}

  • 動態(tài)修改線程池的類,通過Spring的監(jiān)聽器監(jiān)控配置刷新方法,實(shí)現(xiàn)動態(tài)更新線程池的參數(shù);

/**
?*?動態(tài)刷新線程池
?*
?*?@author?wangtongzhou
?*?@since?2022-03-13?14:13
?*/
@Component
@Slf4j
public?class?DynamicThreadPoolManager?{


????@Autowired
????private?DynamicThreadPoolProperties?dynamicThreadPoolProperties;

????/**
?????*?存儲線程池對象
?????*/
????public?Map<String,?ThreadPoolMonitor>?threadPoolExecutorMap?=?new?HashMap<>();


????public?Map<String,?ThreadPoolMonitor>?getThreadPoolExecutorMap()?{
????????return?threadPoolExecutorMap;
????}


????/**
?????*?初始化線程池
?????*/
????@PostConstruct
????public?void?init()?{
????????createThreadPools(dynamicThreadPoolProperties);
????}

????/**
?????*?初始化線程池的創(chuàng)建
?????*
?????*?@param?dynamicThreadPoolProperties
?????*/
????private?void?createThreadPools(DynamicThreadPoolProperties?dynamicThreadPoolProperties)?{
????????dynamicThreadPoolProperties.getExecutors().forEach(config?->?{
????????????if?(!threadPoolExecutorMap.containsKey(config.getThreadPoolName()))?{
????????????????ThreadPoolMonitor?threadPoolMonitor?=?new?ThreadPoolMonitor(
????????????????????????config.getCorePoolSize(),
????????????????????????config.getMaxPoolSize(),
????????????????????????config.getKeepAliveTime(),
????????????????????????config.getUnit(),
????????????????????????new?ResizableCapacityLinkedBlockingQueue<>(config.getQueueCapacity()),
????????????????????????RejectedExecutionHandlerEnum.getRejectedExecutionHandler(config.getRejectedExecutionType()),
????????????????????????config.getThreadPoolName()
????????????????);
????????????????threadPoolExecutorMap.put(config.getThreadPoolName(),
????????????????????????threadPoolMonitor);
????????????}

????????});
????}

????/**
?????*?調(diào)整線程池
?????*
?????*?@param?dynamicThreadPoolProperties
?????*/
????private?void?changeThreadPools(DynamicThreadPoolProperties?dynamicThreadPoolProperties)?{
????????dynamicThreadPoolProperties.getExecutors().forEach(config?->?{
????????????ThreadPoolExecutor?threadPoolExecutor?=?threadPoolExecutorMap.get(config.getThreadPoolName());
????????????if?(Objects.nonNull(threadPoolExecutor))?{
????????????????threadPoolExecutor.setCorePoolSize(config.getCorePoolSize());
????????????????threadPoolExecutor.setMaximumPoolSize(config.getMaxPoolSize());
????????????????threadPoolExecutor.setKeepAliveTime(config.getKeepAliveTime(),?config.getUnit());
????????????????threadPoolExecutor.setRejectedExecutionHandler(RejectedExecutionHandlerEnum.getRejectedExecutionHandler(config.getRejectedExecutionType()));
????????????????BlockingQueue<Runnable>?queue?=?threadPoolExecutor.getQueue();
????????????????if?(queue?instanceof?ResizableCapacityLinkedBlockingQueue)?{
????????????????????((ResizableCapacityLinkedBlockingQueue<Runnable>)?queue).setCapacity(config.getQueueCapacity());
????????????????}
????????????}
????????});
????}


????@EventListener
????public?void?envListener(EnvironmentChangeEvent?event)?{
????????log.info("配置發(fā)生變更"?+?event);
????????changeThreadPools(dynamicThreadPoolProperties);
????}

}
  • DynamicThreadPoolPropertiesController對外暴露兩個方法,第一個通過ContextRefresher提供對外刷新配置的接口,實(shí)現(xiàn)及時更新配置信息,第二提供一個查詢接口的方法,

/**
?*?動態(tài)修改線程池參數(shù)
?*
?*?@author?wangtongzhou
?*?@since?2022-03-13?17:27
?*/
@RestController
public?class?DynamicThreadPoolPropertiesController?{

????@Autowired
????private?ContextRefresher?contextRefresher;
????private?DynamicThreadPoolProperties?dynamicThreadPoolProperties;
????private?DynamicThreadPoolManager?dynamicThreadPoolManager;
????@PostMapping("/threadPool/properties")
????public?void?update()?{
????????ThreadPoolProperties?threadPoolProperties?=
????????????????dynamicThreadPoolProperties.getExecutors().get(0);
????????threadPoolProperties.setCorePoolSize(20);
????????threadPoolProperties.setMaxPoolSize(50);
????????threadPoolProperties.setQueueCapacity(200);
????????threadPoolProperties.setRejectedExecutionType("CallerRunsPolicy");
????????contextRefresher.refresh();
????}
????@GetMapping("/threadPool/properties")
????public?Map<String,?Object>?queryThreadPoolProperties()?{
????????Map<String,?Object>?metricMap?=?new?HashMap<>();
????????List<Map>?threadPools?=?new?ArrayList<>();
????????dynamicThreadPoolManager.getThreadPoolExecutorMap().forEach((k,?v)?->?{
????????????ThreadPoolMonitor?threadPoolMonitor?=?(ThreadPoolMonitor)?v;
????????????Map<String,?Object>?poolInfo?=?new?HashMap<>();
????????????poolInfo.put("thread.pool.name",?k);
????????????poolInfo.put("thread.pool.core.size",?threadPoolMonitor.getCorePoolSize());
????????????poolInfo.put("thread.pool.largest.size",?threadPoolMonitor.getLargestPoolSize());
????????????poolInfo.put("thread.pool.max.size",?threadPoolMonitor.getMaximumPoolSize());
????????????poolInfo.put("thread.pool.thread.count",?threadPoolMonitor.getPoolSize());
????????????poolInfo.put("thread.pool.max.costTime",?threadPoolMonitor.getMaxCostTime());
????????????poolInfo.put("thread.pool.average.costTime",?threadPoolMonitor.getAverageCostTime());
????????????poolInfo.put("thread.pool.min.costTime",?threadPoolMonitor.getMinCostTime());
????????????poolInfo.put("thread.pool.active.count",?threadPoolMonitor.getActiveCount());
????????????poolInfo.put("thread.pool.completed.taskCount",?threadPoolMonitor.getCompletedTaskCount());
????????????poolInfo.put("thread.pool.queue.name",?threadPoolMonitor.getQueue().getClass().getName());
????????????poolInfo.put("thread.pool.rejected.name",?threadPoolMonitor.getRejectedExecutionHandler().getClass().getName());
????????????poolInfo.put("thread.pool.task.count",?threadPoolMonitor.getTaskCount());
????????????threadPools.add(poolInfo);
????????});
????????metricMap.put("threadPools",?threadPools);
????????return?metricMap;
}

整體上的流程到這里就完成了,算是一個Demo版,對于該組件更深入的思考我認(rèn)為還可以做以下三件事情:

  • 應(yīng)該以starter的形式嵌入到應(yīng)用,通過判斷啟動類加載的Appllo、Nacos還是默認(rèn)實(shí)現(xiàn);

  • 對外可以Push、也可以是日志,還可以支持各種庫,提供豐富的輸出形式,這個

到此這篇關(guān)于基于Spring Boot的線程池監(jiān)控方案的文章就介紹到這了,更多相關(guān)Spring Boot的線程池監(jiān)控內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家!

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