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java.lang.management

public Class MemoryNotificationInfo

extends Object
Class Inheritance
Imports
javax.management.openmbean.CompositeData, sun.management.MemoryNotifInfoCompositeData

The information about a memory notification.

A memory notification is emitted by MemoryMXBean when the Java virtual machine detects that the memory usage of a memory pool is exceeding a threshold value. The notification emitted will contain the memory notification information about the detected condition:

A CompositeData representing the MemoryNotificationInfo object is stored in the user data of a notification. The from method is provided to convert from a CompositeData to a MemoryNotificationInfo object. For example:

     Notification notif;

     // receive the notification emitted by MemoryMXBean and set to notif
     ...

     String notifType = notif.getType();
     if (notifType.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED) ||
         notifType.equals(MemoryNotificationInfo.MEMORY_COLLECTION_THRESHOLD_EXCEEDED)) {
         // retrieve the memory notification information
         CompositeData cd = (CompositeData) notif.getUserData();
         MemoryNotificationInfo info = MemoryNotificationInfo.from(cd);
         ....
     }

The types of notifications emitted by MemoryMXBean are:

Author
Mandy Chung
Since
1.5

Field Summary

Modifier and TypeField and Description
private final long
public static final String
MEMORY_COLLECTION_THRESHOLD_EXCEEDED

Notification type denoting that the memory usage of a memory pool is greater than or equal to its collection usage threshold after the Java virtual machine has expended effort in recycling unused objects in that memory pool.

public static final String
MEMORY_THRESHOLD_EXCEEDED

Notification type denoting that the memory usage of a memory pool has reached or exceeded its usage threshold value.

private final String
private final MemoryUsage

Constructor Summary

AccessConstructor and Description
public
MemoryNotificationInfo(String
The name of the memory pool which triggers this notification.
poolName
,
MemoryUsage
Memory usage of the memory pool.
usage
,
long
The threshold crossing count.
count
)

Constructs a MemoryNotificationInfo object.

pack-priv

Method Summary

Modifier and TypeMethod and Description
public static MemoryNotificationInfo

Returns:

a MemoryNotificationInfo object represented by cd if cd is not null; null otherwise.
from
(CompositeData
CompositeData representing a MemoryNotificationInfo
cd
)

Returns a MemoryNotificationInfo object represented by the given CompositeData.

public long

Returns:

the number of times that the memory usage has crossed a threshold when the notification was constructed.
getCount
()

Returns the number of times that the memory usage has crossed a threshold when the notification was constructed.

public String

Returns:

the name of the memory pool that triggers this notification.
getPoolName
()

Returns the name of the memory pool that triggers this notification.

public MemoryUsage

Returns:

the memory usage of the memory pool when this notification was constructed.
getUsage
()

Returns the memory usage of the memory pool when this notification was constructed.

Inherited from java.lang.Object:
cloneequalsfinalizegetClasshashCodenotifynotifyAlltoStringwaitwaitwait

Field Detail

countback to summary
private final long count
MEMORY_COLLECTION_THRESHOLD_EXCEEDEDback to summary
public static final String MEMORY_COLLECTION_THRESHOLD_EXCEEDED

Notification type denoting that the memory usage of a memory pool is greater than or equal to its collection usage threshold after the Java virtual machine has expended effort in recycling unused objects in that memory pool. This notification is emitted by MemoryMXBean. The value of this notification type is java.management.memory.collection.threshold.exceeded.

MEMORY_THRESHOLD_EXCEEDEDback to summary
public static final String MEMORY_THRESHOLD_EXCEEDED

Notification type denoting that the memory usage of a memory pool has reached or exceeded its usage threshold value. This notification is emitted by MemoryMXBean. Subsequent crossing of the usage threshold value does not cause further notification until the memory usage has returned to become less than the usage threshold value. The value of this notification type is java.management.memory.threshold.exceeded.

poolNameback to summary
private final String poolName
usageback to summary
private final MemoryUsage usage

Constructor Detail

MemoryNotificationInfoback to summary
public MemoryNotificationInfo(String poolName, MemoryUsage usage, long count)

Constructs a MemoryNotificationInfo object.

Parameters
poolName:String

The name of the memory pool which triggers this notification.

usage:MemoryUsage

Memory usage of the memory pool.

count:long

The threshold crossing count.

MemoryNotificationInfoback to summary
pack-priv MemoryNotificationInfo(CompositeData cd)

Method Detail

fromback to summary
public static MemoryNotificationInfo from(CompositeData cd)

Returns a MemoryNotificationInfo object represented by the given CompositeData. The given CompositeData must contain the following attributes:

The attributes and the types the given CompositeData contains
Attribute Name Type
poolName java.lang.String
usage javax.management.openmbean.CompositeData
count java.lang.Long
Parameters
cd:CompositeData

CompositeData representing a MemoryNotificationInfo

Returns:MemoryNotificationInfo

a MemoryNotificationInfo object represented by cd if cd is not null; null otherwise.

Exceptions
IllegalArgumentException:
if cd does not represent a MemoryNotificationInfo object.
getCountback to summary
public long getCount()

Returns the number of times that the memory usage has crossed a threshold when the notification was constructed. For usage threshold notifications, this count will be the threshold count. For collection threshold notifications, this count will be the collection usage threshold count.

Returns:long

the number of times that the memory usage has crossed a threshold when the notification was constructed.

getPoolNameback to summary
public String getPoolName()

Returns the name of the memory pool that triggers this notification. The memory pool usage has crossed a threshold.

Returns:String

the name of the memory pool that triggers this notification.

getUsageback to summary
public MemoryUsage getUsage()

Returns the memory usage of the memory pool when this notification was constructed.

Returns:MemoryUsage

the memory usage of the memory pool when this notification was constructed.