1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19 package org.apache.hadoop.metrics2.impl;
20
21 import java.util.concurrent.ScheduledFuture;
22 import java.util.concurrent.TimeUnit;
23
24 import org.apache.commons.logging.Log;
25 import org.apache.commons.logging.LogFactory;
26 import org.apache.hadoop.classification.InterfaceAudience;
27 import org.apache.hadoop.metrics2.MetricsExecutor;
28 import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
29 import org.apache.hadoop.metrics2.lib.MetricsExecutorImpl;
30
31
32
33
34
35
36
37
38
39 @edu.umd.cs.findbugs.annotations.SuppressWarnings(
40 value="LI_LAZY_INIT_STATIC",
41 justification="Yeah, its weird but its what we want")
42 @InterfaceAudience.Private
43 public class JmxCacheBuster {
44 private static final Log LOG = LogFactory.getLog(JmxCacheBuster.class);
45 private static Object lock = new Object();
46 private static ScheduledFuture fut = null;
47 private static MetricsExecutor executor = new MetricsExecutorImpl();
48
49
50
51
52 public static void clearJmxCache() {
53
54
55 if (fut == null || (!fut.isDone() && fut.getDelay(TimeUnit.MILLISECONDS) > 100)) return;
56
57 synchronized (lock) {
58 fut = executor.getExecutor().schedule(new JmxCacheBusterRunnable(), 5, TimeUnit.SECONDS);
59 }
60 }
61
62 static class JmxCacheBusterRunnable implements Runnable {
63
64 @Override
65 public void run() {
66 LOG.trace("Clearing JMX mbean cache.");
67
68
69
70 try {
71 if (DefaultMetricsSystem.instance() != null ) {
72 DefaultMetricsSystem.instance().stop();
73 DefaultMetricsSystem.instance().start();
74 }
75
76 } catch (Exception exception ) {
77 LOG.debug("error clearing the jmx it appears the metrics system hasn't been started", exception);
78 }
79 }
80 }
81 }