Class MemoryNotificationInfo
- java.lang.Object
-
- java.lang.management.MemoryNotificationInfo
public class MemoryNotificationInfo extends Object
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:
- 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 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:
- 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
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static 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. |
static String | MEMORY_THRESHOLD_EXCEEDED | Notification type denoting that the memory usage of a memory pool has reached or exceeded its usage threshold value. |
Constructor Summary
Constructor | Description |
---|---|
MemoryNotificationInfo(String poolName,
MemoryUsage usage,
long count) | Constructs a |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
static MemoryNotificationInfo | from(CompositeData cd) | Returns a |
long | getCount() | Returns the number of times that the memory usage has crossed a threshold when the notification was constructed. |
String | getPoolName() | Returns the name of the memory pool that triggers this notification. |
MemoryUsage | getUsage() | Returns the memory usage of the memory pool when this notification was constructed. |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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 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
.
- 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 by MemoryMXBean
. The value of this notification type is java.management.memory.collection.threshold.exceeded
.
- See Also:
- Constant Field Values
Constructor Detail
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.
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 the threshold
count
. For collection threshold notifications, this count will be the collection 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:
-
cd
-CompositeData
representing aMemoryNotificationInfo
- Returns:
- a
MemoryNotificationInfo
object represented bycd
ifcd
is notnull
;null
otherwise. - Throws:
-
IllegalArgumentException
- ifcd
does not represent aMemoryNotificationInfo
object.