JavaTM 2 Platform Std. Ed. v1.6.0
java.lang.management
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 the
collection 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
Method Summary |
static MemoryNotificationInfo |
from(CompositeData cd)
Returns a MemoryNotificationInfo object represented by the
given CompositeData. |
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 inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
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
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.
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 a
MemoryNotificationInfo
- Returns:
- a MemoryNotificationInfo object represented
by cd if cd is not null;
null otherwise.
- Throws:
IllegalArgumentException - if cd does not
represent a MemoryNotificationInfo object.
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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