compact3
java.lang.management
Class MemoryNotificationInfo
- java.lang.Object
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- java.lang.management.MemoryNotificationInfo
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public class MemoryNotificationInfo extends Object
The information about a memory notification.A memory notification is emitted by
MemoryMXBeanwhen 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
usage threshold count. For collection threshold notifications, this count will be thecollection usage threshold count.
A
CompositeDatarepresenting the MemoryNotificationInfo object is stored in theuser dataof anotification. Thefrommethod 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
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
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.
- Since:
- 1.5
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Field Summary
Fields Modifier and Type Field and Description static StringMEMORY_COLLECTION_THRESHOLD_EXCEEDEDNotification 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.static StringMEMORY_THRESHOLD_EXCEEDEDNotification type denoting that the memory usage of a memory pool has reached or exceeded its usage threshold value.
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Constructor Summary
Constructors Constructor and Description MemoryNotificationInfo(String poolName, MemoryUsage usage, long count)Constructs a MemoryNotificationInfo object.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method and Description static MemoryNotificationInfofrom(CompositeData cd)Returns a MemoryNotificationInfo object represented by the given CompositeData.longgetCount()Returns the number of times that the memory usage has crossed a threshold when the notification was constructed.StringgetPoolName()Returns the name of the memory pool that triggers this notification.MemoryUsagegetUsage()Returns the memory usage of the memory pool when this notification was constructed.
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Field Detail
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 byMemoryMXBean. 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.- See Also:
- Constant Field Values
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 byMemoryMXBean. The value of this notification type is java.management.memory.collection.threshold.exceeded.- See Also:
- Constant Field Values
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Constructor Detail
MemoryNotificationInfo
public MemoryNotificationInfo(String poolName, MemoryUsage usage, long count)
Constructs a MemoryNotificationInfo object.- Parameters:
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poolName- The name of the memory pool which triggers this notification. -
usage- Memory usage of the memory pool. -
count- The threshold crossing count.
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Method Detail
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.
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 thethreshold count. For collection threshold notifications, this count will be thecollection usage threshold count.- Returns:
- the number of times that the memory usage has crossed a threshold when the notification was constructed.
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:
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cd- CompositeData representing a MemoryNotificationInfo - Returns:
- a MemoryNotificationInfo object represented by cd if cd is not null; null otherwise.
- Throws:
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IllegalArgumentException- if cd does not represent a MemoryNotificationInfo object.
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For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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