jdk.lang.management.MemoryNotificationInfo — clojure-interop/java.lang.management 1.0.5

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.

*-memory-collection-threshold-exceeded clj

Static Constant.

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.

type: java.lang.String

*-memory-threshold-exceeded clj

Static Constant.

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.

type: java.lang.String

*from clj

(*from 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

cd - CompositeData representing a MemoryNotificationInfo - javax.management.openmbean.CompositeData

returns: a MemoryNotificationInfo object represented by cd if cd is not null; null otherwise. - java.lang.management.MemoryNotificationInfo

throws: java.lang.IllegalArgumentException - if cd does not represent a MemoryNotificationInfo object.

->memory-notification-info clj

(->memory-notification-info pool-name usage count)

Constructor.

Constructs a MemoryNotificationInfo object.

pool-name - The name of the memory pool which triggers this notification. - java.lang.String usage - Memory usage of the memory pool. - java.lang.management.MemoryUsage count - The threshold crossing count. - long

get-count clj

(get-count this)

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. - long

get-pool-name clj

(get-pool-name this)

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. - java.lang.String

get-usage clj

(get-usage this)

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. - java.lang.management.MemoryUsage