org.jahia.tools.jvm

Class ThreadMonitor

java.lang.Object

org.jahia.tools.jvm.ThreadMonitor

public class ThreadMonitor
extends Object

Warning : generating thread dumps is an operation that locks the JVM and therefore should not be done while high load is running on the system.

Field Summary

Fields

Modifier and Type	Field and Description
static String	THREAD_MONITOR_DEACTIVATED

Method Summary

Modifier and Type	Method and Description
File	dumpThreadInfo(boolean toSysOut, boolean toFile) Prints the thread dump information to System.out or/and to a file.
File	dumpThreadInfoWithInterval(boolean toSysOut, boolean toFile, int threadDumpCount, int intervalSeconds) Starts a background thread to do series of thread dumps with the specified interval.
String	findDeadlock() Checks if any threads are deadlocked.
void	generateThreadInfo(Writer writer) Generates a string with the full thread dump information.
long	getDumpsGenerated()
static ThreadMonitor	getInstance() Retrieves the singleton instance, creating it if it doesn't exist yet.
long	getLastDumpTime()
long	getMinimalIntervalBetweenDumps()
boolean	isActivated()
boolean	isDebugLogging()
boolean	isDumping()
void	setActivated(boolean activated) With this method you can activate/deactivate thread dumping methods.
void	setDebugLogging(boolean debugLogging) Activate this to output concurrent call logging to System.out
void	setMinimalIntervalBetweenDumps(long minimalIntervalBetweenDumps) Sets the minimal interval allowed between thread dumps.
static void	shutdownInstance() Shuts down the singleton instance, calls this when undeploying your application, or call it from the dependency injection system upon destruction of the application context.

Methods inherited from class java.lang.Object

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

Field Detail

THREAD_MONITOR_DEACTIVATED

public static final String THREAD_MONITOR_DEACTIVATED

See Also:

Constant Field Values

Method Detail

getInstance

public static ThreadMonitor getInstance()

Retrieves the singleton instance, creating it if it doesn't exist yet. Be sure to call the shutdownInstance() method once you no longer need it.

Returns:

shutdownInstance

public static void shutdownInstance()

Shuts down the singleton instance, calls this when undeploying your application, or call it from the dependency injection system upon destruction of the application context.

isDebugLogging

public boolean isDebugLogging()

setDebugLogging

public void setDebugLogging(boolean debugLogging)

Activate this to output concurrent call logging to System.out

Parameters:

debugLogging -

isActivated

public boolean isActivated()

setActivated

public void setActivated(boolean activated)

With this method you can activate/deactivate thread dumping methods. If deactivated, the methods will simply do nothing.

Parameters:

activated -

getMinimalIntervalBetweenDumps

public long getMinimalIntervalBetweenDumps()

setMinimalIntervalBetweenDumps

public void setMinimalIntervalBetweenDumps(long minimalIntervalBetweenDumps)

Sets the minimal interval allowed between thread dumps. This makes it easy to avoid loading the CPU with thread dumps under heavy load. The default value is 20ms between two thread dumps. If a thread dump is requested before the interval has elapsed it will simply be ignored (there is no queuing). Some methods that return a String will indicate this behavior.

Parameters:

minimalIntervalBetweenDumps - specified in milliseconds (default value is 20ms).

isDumping

public boolean isDumping()

dumpThreadInfo

public File dumpThreadInfo(boolean toSysOut,
                           boolean toFile)

Prints the thread dump information to System.out or/and to a file.

Parameters:

toSysOut - print the generated thread dump to a System.out

toFile - print the generated thread dump to a file

Returns:

the file where the thread dumps will be performed into, if the dumps are done into a file

dumpThreadInfoWithInterval

public File dumpThreadInfoWithInterval(boolean toSysOut,
                                       boolean toFile,
                                       int threadDumpCount,
                                       int intervalSeconds)

Starts a background thread to do series of thread dumps with the specified interval.

Parameters:

toSysOut - print the generated thread dump to a System.out

toFile - print the generated thread dump to a file

threadDumpCount - the number of thread dumps to do

intervalSeconds - the interval between thread dumps in seconds

Returns:

the file where the thread dumps will be performed into, if the dumps are done into a file

findDeadlock

public String findDeadlock()

Checks if any threads are deadlocked. If any, print the thread dump information.

generateThreadInfo

public void generateThreadInfo(Writer writer)

Generates a string with the full thread dump information.

Parameters:

writer - the output writer

getDumpsGenerated

public long getDumpsGenerated()

getLastDumpTime

public long getLastDumpTime()