org.apache.flink.streaming.runtime.io

类 MultipleFuturesAvailabilityHelper

java.lang.Object

org.apache.flink.streaming.runtime.io.MultipleFuturesAvailabilityHelper

@Internal
public class MultipleFuturesAvailabilityHelper
extends Object

This class is semi-thread safe. Only method notifyCompletion() is allowed to be executed from an outside of the task thread.

It solves a problem of a potential memory leak as described in FLINK-25728. In short we have to ensure, that if there is one input (future) that rarely (or never) completes, that such future would not prevent previously returned combined futures (like CompletableFuture.anyOf(CompletableFuture[]) from being garbage collected. Additionally, we don't want to accumulate more and more completion stages on such rarely completed future, so we are registering CompletableFuture.thenRun(Runnable) only if it has not already been done.

Note resetToUnAvailable() doesn't de register previously registered futures. If future was registered in the past, but for whatever reason now it is not, such future can still complete the newly created future.

It might be no longer needed after upgrading to JDK9 (https://bugs.openjdk.java.net/browse/JDK-8160402).

构造器概要

构造器

构造器和说明
MultipleFuturesAvailabilityHelper(int size)

方法概要

限定符和类型	方法和说明
void	anyOf(int idx, CompletableFuture<?> availabilityFuture) Combine availabilityFuture using anyOf logic with other previously registered futures.
CompletableFuture<?>	getAvailableFuture()
void	resetToUnAvailable()

从类继承的方法 java.lang.Object

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

构造器详细资料

MultipleFuturesAvailabilityHelper

public MultipleFuturesAvailabilityHelper(int size)

方法详细资料

getAvailableFuture

public CompletableFuture<?> getAvailableFuture()

返回:

combined future using anyOf logic

resetToUnAvailable

public void resetToUnAvailable()

anyOf

public void anyOf(int idx,
                  CompletableFuture<?> availabilityFuture)

Combine availabilityFuture using anyOf logic with other previously registered futures.