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Metrics是一个给JAVA提供度量工具的包，在JAVA代码中嵌入Metrics代码，可以方便的对业务代码的各个指标进行监控，同时，Metrics能够很好的跟Ganlia、Graphite结合，方便的提供图形化接口。
下面简单介绍下Metrics如何使用。
只需要增加metrics-core即可使用
<dependency>
<groupId>com.yammer.metrics</groupId> <artifactId>metrics-core</artifactId> <version>2.2.0</version> </dependency>
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下面通过一些测试代码介绍Metrics每个组件的使用，比较简单，基本看代码就懂了，这里不做过多介绍，请结合介绍一起看，这里相当于完善代码。
最简单的度量指标，每次相当于重置这个值。
package com.alibaba.cxf.test.metric; import java.util.LinkedList;import java.util.Queue;import java.util.concurrent.TimeUnit; import com.yammer.metrics.Metrics;import com.yammer.metrics.core.Counter;import com.yammer.metrics.core.Gauge;import com.yammer.metrics.reporting.ConsoleReporter; /** * TODO * @author scutshuxue.chenxf */public class TestGauges { public static Queue queue = new LinkedList (); public static void main(String[] args) throws InterruptedException{ ConsoleReporter.enable(5,TimeUnit.SECONDS); Gauge g = Metrics.newGauge(TestGauges.class, "pending-jobs", newGauge () { @Override public Integer value() { return queue.size(); } }); queue.add("ssss"); System.out.println(g.value()); while(true){ Thread.sleep(1000); } }} 执行效果如下：
12-12-20 14:48:53==============================================================com.alibaba.cxf.test.metric.TestGauges: pending-jobs: value = 1
代码中都增加了ConsoleReporter.enable(1, TimeUnit.SECONDS);语句，通过这个命令，可以每秒钟将度量指标打印在屏幕上，理解起来会有更清楚的理解。
package com.alibaba.cxf.test.metric; import java.util.LinkedList;import java.util.Queue;import java.util.concurrent.TimeUnit; import com.yammer.metrics.Metrics;import com.yammer.metrics.core.Counter;import com.yammer.metrics.reporting.ConsoleReporter; /** * TODO * @author scutshuxue.chenxf */public class TestCounter { private final Counter pendingJobs = Metrics.newCounter(TestCounter.class, "pending-jobs"); private final Queue queue = new LinkedList (); public void add(Stringstr) { pendingJobs.inc(); queue.offer(str); } public String take() { pendingJobs.dec(); return queue.poll(); } /** * TODO * @author scutshuxue.chenxf * @param args * void * @throws InterruptedException */ public static void main(String[]args) throws InterruptedException { // TODOAuto-generated method stub TestCounter tc =new TestCounter(); ConsoleReporter.enable(1,TimeUnit.SECONDS); while(true){ tc.add("1"); Thread.sleep(1000); } } }
效果如下：
12-12-20 14:48:53==============================================================com.alibaba.cxf.test.metric.TestGauges: pending-jobs: value = 1
Meters会将最近1分钟，5分钟，15分钟的TPS（每秒处理的request数）给打印出来，还有所有时间的TPS。
package com.alibaba.cxf.test.metric; import java.util.concurrent.TimeUnit; import com.yammer.metrics.Metrics;import com.yammer.metrics.core.Meter;import com.yammer.metrics.reporting.ConsoleReporter; /** * TODO * @author scutshuxue.chenxf */public class TestMeters { private static Meter meter = Metrics.newMeter(TestMeters.class, "requests","requests", TimeUnit.SECONDS); public static void main(String[] args) throws InterruptedException{ ConsoleReporter.enable(1,TimeUnit.SECONDS); while(true){ meter.mark(); meter.mark(); Thread.sleep(1000); } }} 效果如下：
12-12-20 15:02:50==============================================================com.alibaba.cxf.test.metric.TestMeters: requests: count = 20 mean rate = 2.20requests/s 1-minute rate = 2.00requests/s 5-minute rate = 2.00requests/s15-minute rate = 2.00requests/s
最大值，最小值，平均值，方差，中位值，百分比数据，如75%,90%,98%,99%的数据在哪个范围内。
package com.alibaba.cxf.test.metric; import java.util.concurrent.TimeUnit; import com.yammer.metrics.Metrics;import com.yammer.metrics.core.Histogram;import com.yammer.metrics.reporting.ConsoleReporter; /** * TODO * @author scutshuxue.chenxf */public class TestHistograms { private static Histogram histo = Metrics.newHistogram(TestHistograms.class,"histo-sizes"); /** * TODO * @author scutshuxue.chenxf * @param args * void * @throws InterruptedException */ public static void main(String[] args) throws InterruptedException { // TODOAuto-generated method stub ConsoleReporter.enable(1,TimeUnit.SECONDS); int i=0; while(true){ histo.update(i++); Thread.sleep(1000); } } } 效果如下：
com.alibaba.cxf.test.metric.TestHistograms: histo-sizes: min = 0.00 max = 5.00 mean = 2.50 stddev = 1.87 median = 2.50 75% <= 4.25 95% <= 5.00 98% <= 5.00 99% <= 5.00 99.9% <= 5.00
时间统计
package com.alibaba.cxf.test.metric; import java.util.Random;import java.util.concurrent.TimeUnit; import com.yammer.metrics.Metrics;import com.yammer.metrics.core.Timer;import com.yammer.metrics.core.TimerContext;import com.yammer.metrics.reporting.ConsoleReporter; /** * TODO * @author scutshuxue.chenxf */public class TestTimers { private static Timer timer = Metrics.newTimer(TestTimers.class, "responses", TimeUnit.MILLISECONDS,TimeUnit.SECONDS); /** * TODO * @author scutshuxue.chenxf * @param args * void * @throws InterruptedException */ public static voidmain(String[] args) throws InterruptedException { // TODOAuto-generated method stub ConsoleReporter.enable(2,TimeUnit.SECONDS); Random rn = newRandom(); timer.time(); System.out.println(); while(true){ TimerContextcontext = timer.time(); Thread.sleep(rn.nextInt(1000)); context.stop(); } } } 效果如下:
com.alibaba.cxf.test.metric.TestTimers: responses: count = 26 mean rate = 2.15calls/s 1-minute rate = 1.70calls/s 5-minute rate = 1.62calls/s 15-minute rate = 1.61calls/s min = 35.47ms max = 878.76ms mean = 462.50ms stddev = 284.91ms median = 419.90ms 75% <=764.13ms 95% <=877.76ms 98% <=878.76ms 99% <=878.76ms 99.9% <=878.76ms
健康检查，如心跳：
package com.alibaba.cxf.test.metric; import java.util.Map;import java.util.Map.Entry;import java.util.Random;import java.util.concurrent.TimeUnit; import com.yammer.metrics.HealthChecks;import com.yammer.metrics.core.HealthCheck;import com.yammer.metrics.reporting.ConsoleReporter; public class DatabaseHealthCheck extends HealthCheck { private static Databasedatabase; private static final Map results = HealthChecks.runHealthChecks(); public DatabaseHealthCheck(Databasedatabase) { super("database"); this.database =database; } @Override public Result check()throws Exception { if(database.isConnected()) { returnResult.healthy(); } else { return Result.unhealthy("Cannotconnect to database" ); } } public static void main(String[] args) throws Exception{ Database db = new Database(); DatabaseHealthCheck checkHealth = new DatabaseHealthCheck(db); HealthChecks.register(checkHealth); while(true){ Map results = HealthChecks.runHealthChecks(); for(Entry entry : results.entrySet()) { if (entry.getValue().isHealthy()) { System.out.println(entry.getKey() +" is healthy"); } else { System.err.println(entry.getKey() +" is UNHEALTHY: " + entry.getValue().getMessage()); } } Thread.sleep(1000); } } }class Database{ static Random rn = newRandom(); public booleanisConnected() { // TODOAuto-generated method stub returnrn.nextBoolean(); } } 效果如下：
com.alibaba.cxf.test.metric.TestTimers: responses: count = 26 mean rate = 2.15calls/s 1-minute rate = 1.70calls/s 5-minute rate = 1.62calls/s 15-minute rate = 1.61calls/s min = 35.47ms max = 878.76ms mean = 462.50ms stddev = 284.91ms median = 419.90ms 75% <=764.13ms 95% <=877.76ms 98% <=878.76ms 99% <=878.76ms 99.9% <=878.76ms
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