Package org.apache.hadoop.hbase.util

Class JvmPauseMonitor

java.lang.Object

org.apache.hadoop.hbase.util.JvmPauseMonitor

@Private
public class JvmPauseMonitor
extends Object

Class which sets up a simple thread which runs in a loop sleeping for a short interval of time. If the sleep takes significantly longer than its target time, it implies that the JVM or host machine has paused processing, which may cause other problems. If such a pause is detected, the thread logs a message. The original JvmPauseMonitor is: ${hadoop-common-project}/hadoop-common/src/main/java/org/apache/hadoop/util/ JvmPauseMonitor.java r1503806 | cmccabe | 2013-07-17 01:48:24 +0800 (Wed, 17 Jul 2013) | 1 line HADOOP-9618. thread which detects GC pauses(Todd Lipcon)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	JvmPauseMonitor.GcTimes
private class	JvmPauseMonitor.Monitor

Field Summary

Fields

Modifier and Type	Field	Description
private static final long	INFO_THRESHOLD_DEFAULT
static final String	INFO_THRESHOLD_KEY
private final long	infoThresholdMs	log INFO if we detect a pause longer than this threshold
private static final org.slf4j.Logger	LOG
private JvmPauseMonitorSource	metricsSource
private Thread	monitorThread
private boolean	shouldRun
private static final long	SLEEP_INTERVAL_MS	The target sleep time
private static final long	WARN_THRESHOLD_DEFAULT
static final String	WARN_THRESHOLD_KEY
private final long	warnThresholdMs	log WARN if we detect a pause longer than this threshold

Constructor Summary

Constructors

Constructor	Description
JvmPauseMonitor(org.apache.hadoop.conf.Configuration conf)
JvmPauseMonitor(org.apache.hadoop.conf.Configuration conf, JvmPauseMonitorSource metricsSource)

Method Summary

Modifier and Type	Method	Description
private String	formatMessage(long extraSleepTime, List<String> gcDiffs)
private Map<String,JvmPauseMonitor.GcTimes>	getGcTimes()
JvmPauseMonitorSource	getMetricsSource()
static void	main(String[] args)	Simple 'main' to facilitate manual testing of the pause monitor.
void	setMetricsSource(JvmPauseMonitorSource metricsSource)
void	start()
void	stop()
void	updateMetrics(long sleepTime, boolean gcDetected)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

LOG

private static final org.slf4j.Logger LOG

SLEEP_INTERVAL_MS

private static final long SLEEP_INTERVAL_MS

The target sleep time

See Also:

• Constant Field Values

warnThresholdMs

private final long warnThresholdMs

log WARN if we detect a pause longer than this threshold

WARN_THRESHOLD_KEY

public static final String WARN_THRESHOLD_KEY

See Also:

• Constant Field Values

WARN_THRESHOLD_DEFAULT

private static final long WARN_THRESHOLD_DEFAULT

See Also:

• Constant Field Values

infoThresholdMs

private final long infoThresholdMs

log INFO if we detect a pause longer than this threshold

INFO_THRESHOLD_KEY

public static final String INFO_THRESHOLD_KEY

See Also:

• Constant Field Values

INFO_THRESHOLD_DEFAULT

private static final long INFO_THRESHOLD_DEFAULT

See Also:

• Constant Field Values

monitorThread

private Thread monitorThread

shouldRun

private volatile boolean shouldRun

metricsSource

private JvmPauseMonitorSource metricsSource

Constructor Details

JvmPauseMonitor

public JvmPauseMonitor(org.apache.hadoop.conf.Configuration conf)

JvmPauseMonitor

public JvmPauseMonitor(org.apache.hadoop.conf.Configuration conf,
 JvmPauseMonitorSource metricsSource)

Method Details

start

public void start()

stop

public void stop()

formatMessage

private String formatMessage(long extraSleepTime,
 List<String> gcDiffs)

getGcTimes

private Map<String,JvmPauseMonitor.GcTimes> getGcTimes()

updateMetrics

public void updateMetrics(long sleepTime,
 boolean gcDetected)

getMetricsSource

public JvmPauseMonitorSource getMetricsSource()

setMetricsSource

public void setMetricsSource(JvmPauseMonitorSource metricsSource)

main

public static void main(String[] args)
                 throws Exception

Simple 'main' to facilitate manual testing of the pause monitor. This main function just leaks memory into a list. Running this class with a 1GB heap will very quickly go into "GC hell" and result in log messages about the GC pauses.

Throws:

Exception