com.ibm.lang.management

Class MemoryMXBeanImpl

java.lang.Object

com.ibm.lang.management.DynamicMXBeanImpl

com.ibm.lang.management.MemoryMXBeanImpl

All Implemented Interfaces:

java.lang.management.MemoryMXBean, javax.management.DynamicMBean, javax.management.NotificationBroadcaster, javax.management.NotificationEmitter

public final class MemoryMXBeanImpl
extends DynamicMXBeanImpl
implements MemoryMXBean, javax.management.NotificationEmitter

Runtime type for MemoryMXBean.

Implementation note. This type of bean is both dynamic and a notification emitter. The dynamic behaviour comes courtesy of the DynamicMXBeanImplsuperclass while the notifying behaviour uses a delegation approach to a private member that implements the NotificationEmitterinterface. Because multiple inheritance is not supported in Java it was a toss up which behaviour would be based on inheritence and which would use delegation. Every other *MXBeanImpl class in this package inherits from the abstract base class DynamicMXBeanImpl so that seemed to be the natural approach for this class too. By choosing not to make this class a subclass of NotificationBroadcasterSupport, the protected handleNotification(javax.management.NotificationListener, javax.management.Notification, java.lang.Object) method cannot be overridden for any custom notification behaviour. However, taking the agile mantra of YAGNI to heart, it was decided that the default implementation of that method will suffice until new requirements prove otherwise.

Since:

1.5

Field Summary

Fields inherited from class com.ibm.lang.management.DynamicMXBeanImpl

info

Method Summary

Methods

Modifier and Type	Method and Description
void	addNotificationListener(javax.management.NotificationListener listener, javax.management.NotificationFilter filter, java.lang.Object handback)
void	gc() Requests the virtual machine to run the system garbage collector.
java.lang.String	getGCMode() Returns the current GC mode as a human-readable string.
java.lang.management.MemoryUsage	getHeapMemoryUsage() Returns the current memory usage of the heap for both live objects and for objects no longer in use which are awaiting garbage collection.
long	getMaxHeapSize() Get the current maximum heap size in bytes.
long	getMaxHeapSizeLimit() Get the maximum size in bytes to which the max heap size could be increased in the currently running VM.
long	getMinHeapSize() Get the minimum heap size in bytes.
java.lang.management.MemoryUsage	getNonHeapMemoryUsage() Returns the current non-heap memory usage for the virtual machine.
javax.management.MBeanNotificationInfo[]	getNotificationInfo()
int	getObjectPendingFinalizationCount() Returns the number of objects in the virtual machine that are awaiting finalization.
long	getSharedClassCacheFreeSpace() Returns the free space in bytes of the cache that the JVM is currently connected to.
long	getSharedClassCacheSize() Returns the total size in bytes of the cache that the JVM is currently connected to.
boolean	isSetMaxHeapSizeSupported() Query whether the VM supports runtime reconfiguration of the maximum heap size through the setMaxHeapSize() call.
boolean	isVerbose() Returns a boolean indication of whether or not the memory system is producing verbose output.
void	removeNotificationListener(javax.management.NotificationListener listener)
void	removeNotificationListener(javax.management.NotificationListener listener, javax.management.NotificationFilter filter, java.lang.Object handback)
void	sendNotification(javax.management.Notification notification)
void	setMaxHeapSize(long size) Set the current maximum heap size to size.
void	setVerbose(boolean value) Updates the verbose output setting of the memory system.

Methods inherited from class com.ibm.lang.management.DynamicMXBeanImpl

getAttribute, getAttributes, getMBeanInfo, getPresentAttribute, getPresentOperation, initMBeanInfo, invoke, setAttribute, setAttributes, setMBeanInfo

Methods inherited from class java.lang.Object

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

Method Detail

gc

public void gc()

Description copied from interface: java.lang.management.MemoryMXBean

Requests the virtual machine to run the system garbage collector.

Specified by:

gc in interface java.lang.management.MemoryMXBean

getHeapMemoryUsage

public java.lang.management.MemoryUsage getHeapMemoryUsage()

Description copied from interface: java.lang.management.MemoryMXBean

Returns the current memory usage of the heap for both live objects and for objects no longer in use which are awaiting garbage collection.

Specified by:

getHeapMemoryUsage in interface java.lang.management.MemoryMXBean

Returns:

an instance of MemoryUsagewhich can be interrogated by the caller.

getNonHeapMemoryUsage

public java.lang.management.MemoryUsage getNonHeapMemoryUsage()

Description copied from interface: java.lang.management.MemoryMXBean

Returns the current non-heap memory usage for the virtual machine.

Specified by:

getNonHeapMemoryUsage in interface java.lang.management.MemoryMXBean

Returns:

an instance of MemoryUsagewhich can be interrogated by the caller.

getObjectPendingFinalizationCount

public int getObjectPendingFinalizationCount()

Description copied from interface: java.lang.management.MemoryMXBean

Returns the number of objects in the virtual machine that are awaiting finalization. The returned value should only be used as an approximate guide.

Specified by:

getObjectPendingFinalizationCount in interface java.lang.management.MemoryMXBean

Returns:

the number of objects awaiting finalization.

isVerbose

public boolean isVerbose()

Description copied from interface: java.lang.management.MemoryMXBean

Returns a boolean indication of whether or not the memory system is producing verbose output.

Specified by:

isVerbose in interface java.lang.management.MemoryMXBean

Returns:

true if verbose output is being produced ; false otherwise.

setVerbose

public void setVerbose(boolean value)

Description copied from interface: java.lang.management.MemoryMXBean

Updates the verbose output setting of the memory system.

Specified by:

setVerbose in interface java.lang.management.MemoryMXBean

Parameters:

value - true enables verbose output ; false disables verbose output.

See Also:

ManagementPermission

getMaxHeapSizeLimit

public long getMaxHeapSizeLimit()

Description copied from interface: MemoryMXBean

Get the maximum size in bytes to which the max heap size could be increased in the currently running VM. This may be larger than the current max heap size.

Returns:

value of -Xmx in bytes

getMaxHeapSize

public long getMaxHeapSize()

Description copied from interface: MemoryMXBean

Get the current maximum heap size in bytes.

Returns:

current value of -Xsoftmx in bytes

getMinHeapSize

public long getMinHeapSize()

Description copied from interface: MemoryMXBean

Get the minimum heap size in bytes.

Returns:

value of -Xms in bytes

setMaxHeapSize

public void setMaxHeapSize(long size)

Description copied from interface: MemoryMXBean

Set the current maximum heap size to size. The parameter specifies the max heap size in bytes and must be between getMinHeapSize() and getMaxHeapSizeLimit(). If this operation is not supported, this method will throw UnsupportedOperationException.

Parameters:

size - new -Xsoftmx value in bytes

isSetMaxHeapSizeSupported

public boolean isSetMaxHeapSizeSupported()

Description copied from interface: MemoryMXBean

Query whether the VM supports runtime reconfiguration of the maximum heap size through the setMaxHeapSize() call.

Returns:

true if setMaxHeapSize is supported, false otherwise

removeNotificationListener

public void removeNotificationListener(javax.management.NotificationListener listener,
                              javax.management.NotificationFilter filter,
                              java.lang.Object handback)
                                throws javax.management.ListenerNotFoundException

Specified by:

removeNotificationListener in interface javax.management.NotificationEmitter

Throws:

javax.management.ListenerNotFoundException

addNotificationListener

public void addNotificationListener(javax.management.NotificationListener listener,
                           javax.management.NotificationFilter filter,
                           java.lang.Object handback)
                             throws java.lang.IllegalArgumentException

Specified by:

addNotificationListener in interface javax.management.NotificationBroadcaster

Throws:

java.lang.IllegalArgumentException

removeNotificationListener

public void removeNotificationListener(javax.management.NotificationListener listener)
                                throws javax.management.ListenerNotFoundException

Specified by:

removeNotificationListener in interface javax.management.NotificationBroadcaster

Throws:

javax.management.ListenerNotFoundException

getNotificationInfo

public javax.management.MBeanNotificationInfo[] getNotificationInfo()

Specified by:

getNotificationInfo in interface javax.management.NotificationBroadcaster

sendNotification

public void sendNotification(javax.management.Notification notification)

getSharedClassCacheSize

public long getSharedClassCacheSize()

Description copied from interface: MemoryMXBean

Returns the total size in bytes of the cache that the JVM is currently connected to.

Returns:

the number of bytes in the shared class cache.

getSharedClassCacheFreeSpace

public long getSharedClassCacheFreeSpace()

Description copied from interface: MemoryMXBean

Returns the free space in bytes of the cache that the JVM is currently connected to.

Returns:

the number of bytes free in the shared class cache.

getGCMode

public java.lang.String getGCMode()

Description copied from interface: MemoryMXBean

Returns the current GC mode as a human-readable string.

Returns:

a String describing the mode the GC is currently operating in