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:
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:
usage threshold exceeded notification.
collection usage threshold exceeded notification.
| Modifier and Type | Field 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 |
| Access | Constructor 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 |
| pack-priv |
| Modifier and Type | Method and Description |
|---|---|
| public static MemoryNotificationInfo | Returns: aMemoryNotificationInfo object represented
by cd if cd is not null;
null otherwise.CompositeData representing a
MemoryNotificationInfoReturns a |
| public long | Returns: the number of times that the memory usage has crossed a threshold when the notification was constructed.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.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.Returns the memory usage of the memory pool when this notification was constructed. |
| count | back to summary |
|---|---|
| private final long count | |
| MEMORY_COLLECTION_THRESHOLD_EXCEEDED | back 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 | |
| MEMORY_THRESHOLD_EXCEEDED | back 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 | |
| poolName | back to summary |
|---|---|
| private final String poolName | |
| usage | back to summary |
|---|---|
| private final MemoryUsage usage | |
| MemoryNotificationInfo | back to summary |
|---|---|
| public MemoryNotificationInfo(String poolName, MemoryUsage usage, long count) Constructs a
| |
| MemoryNotificationInfo | back to summary |
|---|---|
| pack-priv MemoryNotificationInfo(CompositeData cd) | |
| from | back to summary | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| public static MemoryNotificationInfo from(CompositeData cd) Returns a
| |||||||||
| getCount | back 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
| |
| getPoolName | back to summary |
|---|---|
| public String getPoolName() Returns the name of the memory pool that triggers this notification. The memory pool usage has crossed a threshold.
| |
| getUsage | back to summary |
|---|---|
| public MemoryUsage getUsage() Returns the memory usage of the memory pool when this notification was constructed.
| |