com.ibm.java.diagnostics.healthcenter.api.vmcontrol

Interface VMControl

public interface VMControl

This class provides methods to trigger events on the virtual machine that is running the monitored application.

Method Summary

Methods

Modifier and Type	Method and Description
void	collectClassHistogramData() Triggers the collection of the class histogram data.
boolean	isClassesDataCollectionEnabled() Returns whether classes data collection is enabled.
boolean	isGCDataCollectionEnabled() Returns whether GC data collection is enabled.
boolean	isIODataCollectionEnabled() Returns whether IO data collection is enabled.
boolean	isLockingDataCollectionEnabled() Returns whether locking data collection is enabled.
boolean	isNativeMemoryDataCollectionEnabled() Returns whether native memory data collection is enabled.
boolean	isProfilingDataCollectionEnabled() Returns whether profiling data collection is enabled.
boolean	isThreadsDataCollectionEnabled() Returns whether threads data collection is enabled.
void	setCallStackCollectionEnabled(boolean value) Enables the collection of call stacks for sampled object allocation events.
void	setClassesDataCollectionEnabled(boolean value) Turns classes data collection on or off.
void	setGCDataCollectionEnabled(boolean value) Turns GC data collection on or off.
void	setIODataCollectionEnabled(boolean value) Turns IO data collection on or off.
void	setLockingDataCollectionEnabled(boolean value) Turns locking data collection on or off.
void	setMaxStackDepth(int depth) Sets the maximum number of stack entries to collect for each event.
void	setNativeMemoryDataCollectionEnabled(boolean value) Turns native memory data collection on or off.
void	setObjectAllocationsEnabled(long lowValue) Enables the collection of object allocation data for objects above a specified size.
void	setObjectAllocationsEnabled(long lowThreshold, long highThreshold) Enables the collection of object allocation data for objects within a specified size range.
void	setProfilingDataCollectionEnabled(boolean value) Turns profiling data collection on or off.
void	setThreadDataCollectionEnabled(boolean value) Turns thread data collection on or off.
void	setThreadStackDepth(int depth) Sets the maximum number of stack entries to collect for each thread.
void	setTracePointEnabled(java.lang.String tracePointID, boolean value) Turns individual trace points on or off.
void	setVerboseGCCollectionEnabled(boolean value) Turns the writing of verbose garbage collection data to a file on or off.
boolean	triggerHeapDump() Triggers a heap dump in the running virtual machine.
boolean	triggerJavaDump() Triggers a Java dump in the running virtual machine.
boolean	triggerSystemDump() Triggers a system dump in the running virtual machine.

Method Detail

setObjectAllocationsEnabled

void setObjectAllocationsEnabled(long lowThreshold,
                               long highThreshold)

Enables the collection of object allocation data for objects within a specified size range.

Parameters:

lowThreshold - the minimum size (in bytes) of the objects to collect data on.

highThreshold - the maximum size (in bytes) of the objects to collect data on.

setObjectAllocationsEnabled

void setObjectAllocationsEnabled(long lowValue)

Enables the collection of object allocation data for objects above a specified size.

Parameters:

lowValue - the minimum size (in bytes) of the objects to collect data on.

setVerboseGCCollectionEnabled

void setVerboseGCCollectionEnabled(boolean value)

Turns the writing of verbose garbage collection data to a file on or off. The name of the file that is created is verbosegc_process_id_n.log, where process_id is the process ID of the monitored JVM, and n is a sequence number. The file is saved in a directory that is local to the monitored JVM specified by the com.ibm.java.diagnostics.healthcenter.output.folder property. If this property is not set, the file is saved in the directory that is specified by the user.dir system property.

Parameters:

value - whether collection is on or off. *

triggerHeapDump

boolean triggerHeapDump()

Triggers a heap dump in the running virtual machine. A heap dump provides a view of memory objects on the Java heap, and is used for memory analysis.

Returns:

true if the trigger command was successfully sent to the virtual machine, false if the command failed.

triggerSystemDump

boolean triggerSystemDump()

Triggers a system dump in the running virtual machine. A system dump is also known as a core dump. System dump creation involves dumping the entire address space, and can therefore produce very large dumps, and take some time to complete.

Returns:

true if the trigger command was successfully sent to the virtual machine, false if the command failed.

triggerJavaDump

boolean triggerJavaDump()

Triggers a Java dump in the running virtual machine. A Java dump is also known as a thread dump of the Java core. The Java dump is used for viewing the thread activity inside the JVM at a given time.

Returns:

true if the trigger command was successfully sent to the virtual machine, false if the command failed.

setCallStackCollectionEnabled

void setCallStackCollectionEnabled(boolean value)

Enables the collection of call stacks for sampled object allocation events.

Parameters:

value - whether the collection is on or off.

setMaxStackDepth

void setMaxStackDepth(int depth)

Sets the maximum number of stack entries to collect for each event.

Parameters:

depth - the maximum number of stack entries.

setGCDataCollectionEnabled

void setGCDataCollectionEnabled(boolean value)

Turns GC data collection on or off. By default, GC data collection is on. Turning this data off can reduce the amount of data generated by the virtual machine that is running the monitored application, and as a result, can reduce the overhead of monitoring an application with the Health Center.

Parameters:

value - whether the collection is on or off.

setIODataCollectionEnabled

void setIODataCollectionEnabled(boolean value)

Turns IO data collection on or off. By default, IO data collection is on. Turning this data off can reduce the amount of data generated by the virtual machine that is running the monitored application, and as a result, can reduce the overhead of monitoring an application with the Health Center.

Parameters:

value - whether the collection is on or off.

setClassesDataCollectionEnabled

void setClassesDataCollectionEnabled(boolean value)

Turns classes data collection on or off. By default, classes data collection is on. Turning this data off can reduce the amount of data generated by the virtual machine that is running the monitored application, and as a result, can reduce the overhead of monitoring an application with the Health Center.

Parameters:

value - whether the collection is on or off.

setLockingDataCollectionEnabled

void setLockingDataCollectionEnabled(boolean value)

Turns locking data collection on or off. By default, locking data collection is on. Turning this data off can reduce the amount of data generated by the virtual machine that is running the monitored application, and as a result, can reduce the overhead of monitoring an application with the Health Center.

Parameters:

value - whether the collection is on or off.

setNativeMemoryDataCollectionEnabled

void setNativeMemoryDataCollectionEnabled(boolean value)

Turns native memory data collection on or off. By default, native memory data collection is on. Turning this data off can reduce the amount of data generated by the virtual machine that is running the monitored application, and as a result, can reduce the overhead of monitoring an application with the Health Center.

Parameters:

value - whether the collection is on or off.

setProfilingDataCollectionEnabled

void setProfilingDataCollectionEnabled(boolean value)

Turns profiling data collection on or off. By default, profiling data collection is on. Turning this data off can reduce the amount of data generated by the virtual machine that is running the monitored application, and as a result, can reduce the overhead of monitoring an application with the Health Center.

Parameters:

value - whether the collection is on or off.

setThreadDataCollectionEnabled

void setThreadDataCollectionEnabled(boolean value)

Turns thread data collection on or off. By default, thread data collection is on. Turning this data off can reduce the amount of data generated by the virtual machine that is running the monitored application, and as a result, can reduce the overhead of monitoring an application with the Health Center.

Parameters:

value - whether the collection is on or off.

setThreadStackDepth

void setThreadStackDepth(int depth)

Sets the maximum number of stack entries to collect for each thread. Setting this to zero will turn off thread stack collection.

Parameters:

depth - the maximum number of stack entries required.

setTracePointEnabled

void setTracePointEnabled(java.lang.String tracePointID,
                        boolean value)
                          throws HealthCenterException

Turns individual trace points on or off.

Parameters:

tracePointID - the ID of the trace point to enable or disable.

value - whether the trace point is on or off.

Throws:

HealthCenterException - if the call is unsuccessful.

isGCDataCollectionEnabled

boolean isGCDataCollectionEnabled()

Returns whether GC data collection is enabled.

Returns:

boolean.

isIODataCollectionEnabled

boolean isIODataCollectionEnabled()

Returns whether IO data collection is enabled.

Returns:

boolean.

isProfilingDataCollectionEnabled

boolean isProfilingDataCollectionEnabled()

Returns whether profiling data collection is enabled.

Returns:

boolean.

isClassesDataCollectionEnabled

boolean isClassesDataCollectionEnabled()

Returns whether classes data collection is enabled.

Returns:

boolean.

isThreadsDataCollectionEnabled

boolean isThreadsDataCollectionEnabled()

Returns whether threads data collection is enabled.

Returns:

boolean.

isNativeMemoryDataCollectionEnabled

boolean isNativeMemoryDataCollectionEnabled()

Returns whether native memory data collection is enabled.

Returns:

boolean.

isLockingDataCollectionEnabled

boolean isLockingDataCollectionEnabled()

Returns whether locking data collection is enabled.

Returns:

boolean.

collectClassHistogramData

void collectClassHistogramData()
                               throws HealthCenterNotSupportedException

Triggers the collection of the class histogram data. For every class loaded, this process collects the number of instances of that class, and the total amount of memory that is used by those instances.

Throws:

HealthCenterNotSupportedException.

HealthCenterNotSupportedException