java.lang.management
class MemoryNotificationInfo

java.lang.Object java.lang.management.MemoryNotificationInfo

Most common way to construct:

CompositeData cd = …;

MemoryNotificationInfo info = MemoryNotificationInfo.from(cd);

Based on 87 examples

public class MemoryNotificationInfo
extends Object

The information about a memory notification.

A memory notification is emitted by {@link 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:

• The name of the memory pool.
• The memory usage of the memory pool when the notification was constructed.
• 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 {@link MemoryPoolMXBean#getUsageThresholdCount usage threshold count}. For collection threshold notifications, this count will be the {@link MemoryPoolMXBean#getCollectionUsageThresholdCount collection usage threshold count}.

A {@link CompositeData CompositeData} representing the MemoryNotificationInfo object is stored in the {@link javax.management.Notification#setUserData user data} of a {@link javax.management.Notification notification}. The {@link #from 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:

• A {@link #MEMORY_THRESHOLD_EXCEEDED usage threshold exceeded notification}.
  This notification will be emitted when the memory usage of a memory pool is increased and has reached or exceeded its usage threshold value. 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.

• A {@link #MEMORY_COLLECTION_THRESHOLD_EXCEEDED collection usage threshold exceeded notification}.
  This notification will be emitted when 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.

MEMORY_COLLECTION_THRESHOLD_EXCEEDED

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 {@link MemoryMXBean}. The value of this notification type is java.management.memory.collection.threshold.exceeded.

MEMORY_THRESHOLD_EXCEEDED

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 {@link 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.

MemoryNotificationInfo

public MemoryNotificationInfo(String poolName,
                              MemoryUsage usage,
                              long count)

Constructs a MemoryNotificationInfo object.

Parameters:

poolName - The name of the memory pool which triggers this notification.

usage - Memory usage of the memory pool.

count - The threshold crossing count.

from

public static MemoryNotificationInfo from(CompositeData cd)

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

Attribute Name	Type
poolName	java.lang.String
usage	javax.management.openmbean.CompositeData
count	java.lang.Long

Parameters:

cd - CompositeData representing a MemoryNotificationInfo

Returns:

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

getCount

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 {@link MemoryPoolMXBean#getUsageThresholdCount threshold count}. For collection threshold notifications, this count will be the {@link MemoryPoolMXBean#getCollectionUsageThresholdCount collection usage threshold count}.

Returns:

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

getPoolName

public String getPoolName()

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

Returns:

the name of the memory pool that triggers this notification.

getUsage

public MemoryUsage getUsage()

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

Returns:

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