com.azul.zing.management

Class PauseDetails

java.lang.Object

com.azul.zing.management.PauseDetails

public class PauseDetails
extends java.lang.Object

A PauseDetails object represents a pause event impacting all the threads in a running Java virtual machine and includes a timestamp specifying the time since the launch of the Java virtual machine process, the duration of the pause, and the reason for the pause (plus additional, optional, very detailed information).

Instances of the PauseDetails class are constructed when a pause occurs. A timestamp representing the wall clock time when the pause occurred, the duration of the pause and the reason for the pause are collected. The timestamp is the number of seconds since the launch of the Java virtual machine. The duration of the pause is in units of seconds. The reason field is a text string describing the reason for the pause. The content of the String that represents the reason for the pause is specific to the implementation of the Java virtual machine.

PauseDetails also has additional, optional, details of the time required for individual steps executed during the pause. The times for the individual steps make it easy to identify potential areas for reducing the total pause duration. Generally, the sum of the additional detailed timing information’s times should add up to the total pause duration.

A PauseDetails object has twelve attributes, supplying the values for three is mandatory:

elapsedTimeSinceJVMStartSec	Wall clock time when the pause occurred in units of elapsed seconds since the start of the JVM.
durationSec	Total pause duration in seconds.
reason	Reason for the pause.
Time Required for Individual Steps
initialThreadsLockAcquireTimeSec	Time required to obtain the threads lock at the beginning of this pause’s processing.
collectorSuspendTimeSec	Time required to suspend any running collector as we prepare to suspend the process’s threads.
threadsNotifyTimeSec	Time required to notify all of the running threads to suspend themselves.
timeForThreadsToSuspendSec	Time spent waiting for all of the threads to suspend. The time returned from timeForThreadsToSuspendSec is also commonly known as Time To Safepoint.
collectorSecondSuspendTimeSec	If the first suspend of any collection in progress done in collectorSuspendTimeSec did not succeed then we need to try again to suspend the collection or collections in progress. collectorSecondSuspendTimeSec is the amount of time required to do the suspension.
operationTimeSec	Time required to perform the operation for which suspension of all the threads is required. The interval reported begins when all of the threads have been suspended and ends when the operation has been completed.
postOperationCleanupTimeSec	Time required for cleanup activities just prior to resumption of thread execution.
timeToWakeupThreadsSec	Time required for all of the threads to resume execution after the notification of each thread to wakeup and resume execution.
pauseId	Unique numeric value that identifies this pause.

Constructor Summary

Constructors

Constructor and Description

PauseDetails(double elapsedTimeSinceJVMStartSec, double durationSec, java.lang.String reason, double initialThreadsLockAcquireTimeSec, double collectorSuspendTimeSec, double threadsNotifyTimeSec, double timeForThreadsToSuspendSec, double collectorSecondSuspendTimeSec, double operationTimeSec, double postOperationCleanupTimeSec, double timeToWakeupThreadsSec, long pauseId) Constructs a PauseDetails object using a String reason.

Method Summary

Methods

Modifier and Type	Method and Description
static PauseDetails	from(javax.management.openmbean.CompositeData cd) Returns a PauseDetails object constructed with the values in the CompositeData parameter.
double	getCollectorSecondSuspendTimeSec() Time required to redo the suspend of a collection in progress if the first suspend (see getCollectorSuspendTimeSec) did not result in a suspension (seldom required to do this a second time).
double	getCollectorSuspendTimeSec() Time required to suspend any collector running as we prepare for the pause.
double	getDurationSec() Total duration of the pause.
double	getElapsedTimeSinceJVMStartSec() Wall clock time when the pause started.
double	getInitialThreadsLockAcquireTimeSec() Time required to obtain the threads lock at the beginning of this pause’s processing.
double	getOperationTimeSec() Time required to perform the operation for which the pause was required.
long	getPauseId() Numeric identifier of this pause.
double	getPostOperationCleanupTimeSec() Time required for cleanup activities just prior to resumption of thread execution.
java.lang.String	getReason() Reason for the pause.
double	getThreadsNotifyTimeSec() Time required to notify all of the running threads to suspend themselves.
double	getTimeForThreadsToSuspendSec() Time spent waiting for all of the threads to suspend (time to safepoint).
double	getTimeToWakeupThreadsSec() Time for all of the threads to resume execution after the notification to wakeup.
java.lang.String	toString() Returns a String object with the information describing this pause time.

Methods inherited from class java.lang.Object

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

Constructor Detail

PauseDetails

public PauseDetails(double elapsedTimeSinceJVMStartSec,
            double durationSec,
            java.lang.String reason,
            double initialThreadsLockAcquireTimeSec,
            double collectorSuspendTimeSec,
            double threadsNotifyTimeSec,
            double timeForThreadsToSuspendSec,
            double collectorSecondSuspendTimeSec,
            double operationTimeSec,
            double postOperationCleanupTimeSec,
            double timeToWakeupThreadsSec,
            long pauseId)

Constructs a PauseDetails object using a String reason.

Parameters:

elapsedTimeSinceJVMStartSec - the time when the pause started (elapsed seconds since Java virtual machine process launch)

durationSec - the total pause duration (seconds)

reason - the reason for the pause

initialThreadsLockAcquireTimeSec - time required to obtain the threads lock at the beginning of this pause’s processing

collectorSuspendTimeSec - time required to suspend any collector running as we prepare for the pause

threadsNotifyTimeSec - time required to notify all of the running threads to suspend themselves

timeForThreadsToSuspendSec - time spent waiting for all of the threads to suspend (time to safepoint)

collectorSecondSuspendTimeSec - time required to redo the suspend of a collection in progress if the previous suspend did not work (seldom required)

operationTimeSec - time required to perform the operation for which the pause is required

postOperationCleanupTimeSec - time required for cleanup activities just prior to resumption of thread execution

timeToWakeupThreadsSec - time that represents the longest interval required for a thread to wakeup after notification

pauseId - numeric identifier of this pause

Throws:

java.lang.IllegalArgumentException - if

• the value of elapsedTimeSinceJVMStartSec or durationSec or the value of any other numeric parameter has a negative value

Method Detail

from

public static PauseDetails from(javax.management.openmbean.CompositeData cd)

Returns a PauseDetails object constructed with the values in the CompositeData parameter.

The CompositeData input parameter must contain the following values:

Attribute Name	Type
elapsedTimeSinceJVMStartSec	java.lang.Double
durationSec	java.lang.Double
reason	java.lang.String
initialThreadsLockAcquireTimeSec	java.lang.Double
collectorSuspendTimeSec	java.lang.Double
threadsNotifyTimeSec	java.lang.Double
timeForThreadsToSuspendSec	java.lang.Double
collectorSecondSuspendTimeSec	java.lang.Double
operationTimeSec	java.lang.Double
postOperationCleanupTimeSec	java.lang.Double
timeToWakeupThreadsSec	java.lang.Double
pauseId	java.lang.Long

Parameters:

cd - The CompositeData object from which to retrieve the required PauseDetails values.

Returns:

PauseDetails object with the cd data values; null otherwise.

Throws:

java.lang.IllegalArgumentException - if cd does not contain PauseDetails values with the attributes described above.

getCollectorSecondSuspendTimeSec

public double getCollectorSecondSuspendTimeSec()

Time required to redo the suspend of a collection in progress if the first suspend (see getCollectorSuspendTimeSec) did not result in a suspension (seldom required to do this a second time).

Returns:

time in seconds required for a suspension of a collection in progress.

getCollectorSuspendTimeSec

public double getCollectorSuspendTimeSec()

Time required to suspend any collector running as we prepare for the pause.

Returns:

time in seconds required to suspend a collection that is in progress.

getDurationSec

public double getDurationSec()

Total duration of the pause.

Returns:

total duration of the pause in seconds.

getElapsedTimeSinceJVMStartSec

public double getElapsedTimeSinceJVMStartSec()

Wall clock time when the pause started.

Returns:

wall clock time when the pause started (in units of seconds from Java virtual machine process launch).

getInitialThreadsLockAcquireTimeSec

public double getInitialThreadsLockAcquireTimeSec()

Time required to obtain the threads lock at the beginning of this pause’s processing.

Returns:

time in seconds required to obtain the threads lock required to begin the pause.

getOperationTimeSec

public double getOperationTimeSec()

Time required to perform the operation for which the pause was required. The interval reported begins when the relevant threads have been suspended and ends when the operation has been completed.

Returns:

total time in seconds required to perform the operation for which the pause was required.

getPauseId

public long getPauseId()

Numeric identifier of this pause. The value represents the number of this pause in the sequence of pauses performed by the Java virtual machine.

Returns:

numeric identifier of this pause.

getPostOperationCleanupTimeSec

public double getPostOperationCleanupTimeSec()

Time required for cleanup activities just prior to resumption of thread execution.

Returns:

time in seconds required for the cleanup operations done just prior to resumption of thread execution.

getReason

public java.lang.String getReason()

Reason for the pause. The reason for the pause depends on the implementation of the Java Virtual Machine.

Returns:

a String describing the reason for the pause.

getThreadsNotifyTimeSec

public double getThreadsNotifyTimeSec()

Time required to notify all of the running threads to suspend themselves.

Returns:

time in seconds required to notify all of the threads that they should suspend themselves.

getTimeForThreadsToSuspendSec

public double getTimeForThreadsToSuspendSec()

Time spent waiting for all of the threads to suspend (time to safepoint). After notification that a thread should suspend, the time value returned represents the amount of time from notification until the last thread suspends.

Returns:

time in seconds waiting for all threads to suspend.

getTimeToWakeupThreadsSec

public double getTimeToWakeupThreadsSec()

Time for all of the threads to resume execution after the notification to wakeup.

Returns:

time in seconds representing the longest amount of time required by any thread to wake up.

toString

public java.lang.String toString()

Returns a String object with the information describing this pause time.

Overrides:

toString in class java.lang.Object

Returns:

String describing this PauseDetails object.