Package io.deephaven.hotspot

Class JvmIntrospectionContext

java.lang.Object

io.deephaven.hotspot.JvmIntrospectionContext

public class JvmIntrospectionContext
extends Object

Utility class to facilitate obtaining data for safepoint pauses count and time between two points in code. A safepoint pause is a "stop the world, pause all threads" event in the HotSpot JVM. Note full Garbage Collection pauses are a dominant cause of safepoint pauses, but there are other triggers like:

1. Deoptimization
2. Biased lock revocation
3. Thread dump
4. Heap inspection
5. Class redefinition

And others; you can see a full list here .

Constructor Summary

Constructors

Constructor	Description
JvmIntrospectionContext()

Method Summary

Modifier and Type	Method	Description
long	deltaSafePointPausesCount()	Number of safepoint pauses between the last two calls to sample()
long	deltaSafePointPausesTimeMillis()	Time in milliseconds fully paused in safepoints between the last two calls to sample()
long	deltaSafePointSyncTimeMillis()	Time in milliseconds getting to a full safepoint stop (safepoint sync time) between the last two calls to sample()
void	endSample()	Sample garbage collection count and times at the point of call.
boolean	hasSafePointData()
void	startSample()

Methods inherited from class java.lang.Object

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

Constructor Details

JvmIntrospectionContext

public JvmIntrospectionContext()

Method Details

hasSafePointData

public boolean hasSafePointData()

startSample

public void startSample()

endSample

public void endSample()

Sample garbage collection count and times at the point of call.

deltaSafePointPausesCount

public long deltaSafePointPausesCount()

Number of safepoint pauses between the last two calls to sample()

Returns:

Number of safepoint pauses.

deltaSafePointPausesTimeMillis

public long deltaSafePointPausesTimeMillis()

Time in milliseconds fully paused in safepoints between the last two calls to sample()

Returns:

Time in milliseconds.

deltaSafePointSyncTimeMillis

public long deltaSafePointSyncTimeMillis()

Time in milliseconds getting to a full safepoint stop (safepoint sync time) between the last two calls to sample()

Returns:

Time in milliseconds