com.facebook.buck.support.jvm

Class GCNotificationEventEmitter

java.lang.Object

com.facebook.buck.support.jvm.GCNotificationEventEmitter

All Implemented Interfaces:

EventListener, NotificationListener

public final class GCNotificationEventEmitter
extends Object
implements NotificationListener

JVM NotificationListener tuned to listen for GC events and emit GC events on the Buck event bus. This class receives GC events directly from the JVM and reports them in as high fidelity as possible to various log systems, where they can be used to correlate JVM GCs with other events in the Buck system.

This class is expected to work the same with any GC, but Buck currently uses the G1 GC, so its heuristics are tuned to that.

Method Summary

Modifier and Type	Method and Description
void	handleNotification(Notification notification, Object handback) Handles a JMX Notification emitted by one of the GC beans that we're listening to.
static void	register(BuckEventBus bus) Registers for GC notifications to be sent to the given event bus.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

register

public static void register(BuckEventBus bus)

Registers for GC notifications to be sent to the given event bus.

Parameters:

bus - The event bus to send GC events to.

handleNotification

public void handleNotification(Notification notification,
                               Object handback)

Handles a JMX Notification emitted by one of the GC beans that we're listening to. This function is called on a special runtime thread that is not visible to debuggers, so if you're trying to break in this method and it's not working, that's why.

Since this is called on a special thread, it's important that it 1) not block and 2) terminate as quickly as possible.

Specified by:

handleNotification in interface NotificationListener

Parameters:

notification - The notification that we've just received from JMX

handback - An instance of the GarbageCollectorMXBean that triggered the event, which we passed explicitly as the third parameter of NotificationBroadcaster.addNotificationListener(NotificationListener, NotificationFilter, Object) in the class constructor.