Java Metrics系統(tǒng)性能監(jiān)控工具的使用詳解

更新時間：2022年11月09日 16:20:31 作者：lfwh

Metrics是一個Java庫，可以對系統(tǒng)進行監(jiān)控，統(tǒng)計一些系統(tǒng)的性能指標。本文就來和大家詳細聊聊這個工具的具體使用，希望對大家有所幫助

前言

Metrics是一個Java庫，可以對系統(tǒng)進行監(jiān)控，統(tǒng)計一些系統(tǒng)的性能指標。

比如一個系統(tǒng)后臺服務，我們可能需要了解一下下面的一些情況：

1、每秒鐘的請求數(shù)是多少（TPS）？

2、平均每個請求處理的時間？

3、請求處理的最長耗時？

4、等待處理的請求隊列長度？

5、又或者一個緩存服務：緩存的命中率？平均查詢緩存的時間？

基本上每一個服務、應用都需要做一個監(jiān)控系統(tǒng)，這需要盡量以少量的代碼，實現(xiàn)統(tǒng)計某類數(shù)據(jù)的功能。

Metric Registries

MetricRegistry類是Metrics的核心，它是存放應用中所有metrics的容器，也是我們使用 Metrics 庫的起點。

MetricRegistry registry = new MetricRegistry();

Metrics 數(shù)據(jù)展示

Metrics 提供了 Report 接口，用于展示 metrics 獲取到的統(tǒng)計數(shù)據(jù)。metrics-core中主要實現(xiàn)了四種 reporter： JMX ，console， SLF4J，和 CSV。在的例子中，我們使用 ConsoleReporter 。

Metrics的五種類型

Gauges

比較簡單的度量指標，只有一個簡單的返回值，例如，我們想衡量一個待處理隊列中任務的個數(shù)，代碼如下：

package com.zyh.maven.metricsdemo;

import com.codahale.metrics.ConsoleReporter;
import com.codahale.metrics.Gauge;
import com.codahale.metrics.MetricRegistry;

import java.util.LinkedList;
import java.util.Queue;
import java.util.concurrent.TimeUnit;

public class GaugeTest {

    public static Queue<String> q = new LinkedList<String>();

    public static void main(String[] args) throws InterruptedException {

        MetricRegistry metricRegistry = new MetricRegistry();
        ConsoleReporter reporter = ConsoleReporter.forRegistry(metricRegistry).build();
        reporter.start(1, TimeUnit.SECONDS);

        metricRegistry.register(MetricRegistry.name(GaugeTest.class, "queue", "size"),
                new Gauge<Integer>(){
                    @Override
                    public Integer getValue() {
                        return q.size();
                    }
                });

        while (true)
        {
            Thread.sleep(1000);
            q.add("lfwhvip");
        }
    }
}

運行結果 :

22-11-3 14:36:28 ================================================================

-- Gauges ----------------------------------------------------------------------
com.zyh.maven.metricsdemo.GaugeTest.queue.size
value = 1

22-11-3 14:36:29 ================================================================

-- Gauges ----------------------------------------------------------------------
com.zyh.maven.metricsdemo.GaugeTest.queue.size
value = 1

Counters

Counter 就是計數(shù)器，Counter 只是用 Gauge 封裝了 AtomicLong ，我們可以使用如下的方法獲得隊列大小，代碼如下：

package com.zyh.maven.metricsdemo;

import com.codahale.metrics.ConsoleReporter;
import com.codahale.metrics.Counter;
import com.codahale.metrics.MetricRegistry;

import java.util.Queue;
import java.util.Random;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.TimeUnit;

public class CounterTest {

    public static Queue<String> q = new LinkedBlockingDeque<String>();

    public static Counter pendingJobs;

    public static Random random = new Random();

    public static void addJob(String job)
    {
        pendingJobs.inc();
        q.offer(job);
    }

    public static String takeJob()
    {
        pendingJobs.dec();
        return q.poll();
    }

    public static void main(String[] args) throws InterruptedException {

        MetricRegistry registry = new MetricRegistry();
        ConsoleReporter reporter = ConsoleReporter.forRegistry(registry).build();
        reporter.start(1, TimeUnit.SECONDS);

        pendingJobs = registry.counter(MetricRegistry.name(Queue.class, "pending-jobs", "size"));

        int num = 1;
        while(true)
        {
            Thread.sleep(200);
            if(random.nextDouble() > 0.7)
            {
                String job = takeJob();
                System.out.println("take job :" + job);
            }else{
                String job = "Job-" + num;
                addJob(job);
                System.out.println("add Job :" + job);
            }
            num++;
        }
    }
}

運行結果

take job :Job-14
add Job :Job-26
add Job :Job-27
add Job :Job-28
add Job :Job-29
22-11-3 14:39:58 ================================================================

-- Counters --------------------------------------------------------------------
java.util.Queue.pending-jobs.size
count = 11

take job :Job-16
add Job :Job-31
add Job :Job-32
take job :Job-17
take job :Job-18
22-11-3 14:39:59 ================================================================

-- Counters --------------------------------------------------------------------
java.util.Queue.pending-jobs.size
count = 10

Meters

Meter度量一系列事件發(fā)生的速率(rate)，例如TPS。Meters會統(tǒng)計最近1分鐘，5分鐘，15分鐘，還有全部時間的速率。

package com.zyh.maven.metricsdemo;

import com.codahale.metrics.ConsoleReporter;
import com.codahale.metrics.Meter;
import com.codahale.metrics.MetricRegistry;

import java.util.Random;
import java.util.concurrent.TimeUnit;

public class MeterTest {

    public static Random random = new Random();

    public static void request(Meter meter)
    {
        System.out.println("request");
        meter.mark();
    }

    public static void request(Meter meter, int n)
    {
        while(n > 0)
        {
            request(meter);
            n--;
        }
    }
    public static void main(String[] args) throws InterruptedException {

        MetricRegistry registry = new MetricRegistry();
        ConsoleReporter reporter = ConsoleReporter.forRegistry(registry).build();
        reporter.start(1, TimeUnit.SECONDS);

        Meter meterTps = registry.meter(MetricRegistry.name(MeterTest.class, "request", "tps"));

        while(true)
        {
            request(meterTps, random.nextInt(5));
            Thread.sleep(1000);
        }
    }
}

運行結果

22-11-7 16:18:38 ===============================================================

-- Meters ----------------------------------------------------------------------
com.example.jkytest.modules.MeterTest.request.tps
count = 8
mean rate = 1.60 events/second
1-minute rate = 1.60 events/second
5-minute rate = 1.60 events/second
15-minute rate = 1.60 events/second

request
request
request
request
22-11-7 16:18:39 ===============================================================

-- Meters ----------------------------------------------------------------------
com.example.jkytest.modules.MeterTest.request.tps
count = 12
mean rate = 2.00 events/second
1-minute rate = 1.60 events/second
5-minute rate = 1.60 events/second
15-minute rate = 1.60 events/second

Histograms

Histogram統(tǒng)計數(shù)據(jù)的分布情況。比如最小值，最大值，中間值，還有中位數(shù)，75百分位，90百分位，95百分位，98百分位，99百分位，和 99.9百分位的值(percentiles)。

package com.example.jkytest.modules;

import com.codahale.metrics.ConsoleReporter;
import com.codahale.metrics.ExponentiallyDecayingReservoir;
import com.codahale.metrics.Histogram;
import com.codahale.metrics.MetricRegistry;

import java.util.Random;
import java.util.concurrent.TimeUnit;

public class HistogramsTest {
    public static Random random = new Random();

    public static void main(String[] args) throws InterruptedException {

        MetricRegistry registry = new MetricRegistry();
        ConsoleReporter reporter = ConsoleReporter.forRegistry(registry).build();
        reporter.start(1, TimeUnit.SECONDS);

        Histogram histogram = new Histogram(new ExponentiallyDecayingReservoir());
        registry.register(MetricRegistry.name(HistogramsTest.class, "request", "histogram"), histogram);

        while (true)
        {
            Thread.sleep(1000);
            histogram.update(random.nextInt(100000));
        }
    }
}

運行結果

-- Histograms ------------------------------------------------------------------
com.example.jkytest.modules.HistogramsTest.request.histogram
count = 1
min = 33246
max = 33246
mean = 33246.00
stddev = 0.00
median = 33246.00
75% <= 33246.00
95% <= 33246.00
98% <= 33246.00
99% <= 33246.00
99.9% <= 33246.00

22-11-7 16:26:34 ===============================================================

-- Histograms ------------------------------------------------------------------
com.example.jkytest.modules.HistogramsTest.request.histogram
count = 2
min = 33246
max = 68864
mean = 51188.56
stddev = 17808.50
median = 68864.00
75% <= 68864.00
95% <= 68864.00
98% <= 68864.00
99% <= 68864.00
99.9% <= 68864.00

Timers

Timer其實是 Histogram 和 Meter 的結合， histogram 某部分代碼/調(diào)用的耗時， meter統(tǒng)計TPS。

package com.example.jkytest.modules;

import com.codahale.metrics.ConsoleReporter;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.Timer;

import java.util.Random;
import java.util.concurrent.TimeUnit;

public class TimerTest {

    public static Random random = new Random();

    public static void main(String[] args) throws InterruptedException {

        MetricRegistry registry = new MetricRegistry();
        ConsoleReporter reporter = ConsoleReporter.forRegistry(registry).build();
        reporter.start(1, TimeUnit.SECONDS);

        Timer timer = registry.timer(MetricRegistry.name(TimerTest.class, "get-latency"));

        Timer.Context ctx;

        while (true)
        {
            ctx = timer.time();
            Thread.sleep(random.nextInt(1000));
            ctx.stop();
        }
    }
}

運行結果

-- Timers ----------------------------------------------------------------------
com.example.jkytest.modules.TimerTest.get-latency
count = 1
mean rate = 1.00 calls/second
1-minute rate = 0.00 calls/second
5-minute rate = 0.00 calls/second
15-minute rate = 0.00 calls/second
min = 560.21 milliseconds
max = 560.21 milliseconds
mean = 560.21 milliseconds
stddev = 0.00 milliseconds
median = 560.21 milliseconds
75% <= 560.21 milliseconds
95% <= 560.21 milliseconds
98% <= 560.21 milliseconds
99% <= 560.21 milliseconds
99.9% <= 560.21 milliseconds