HystrixCircuitBreaker allowRequest() doesn't have idempotent behaviour in latest release 1.5.18

[rohansuri]

The master includes this change PR #1568, which made allowRequest() idempotent, which was released in 1.5.12. However the latest release 1.5.18 doesn't have it.

Does anyone know why?

Thanks

[didi-moritz]

1.5.11 was re-released as 1.5.18. See #1891 for explanation.

[l2dy]

The change might have fixed a race condition in HystrixCommandMetrics that could introduce memory leaks.

resetStream() may be called in parallel with isOpen() or allowRequest(), occasionally leaking subscriptions with re-subscription of counterSubject in BucketedCounterStream.startCachingStreamValuesIfUnstarted().

Hystrix/hystrix-core/src/main/java/com/netflix/hystrix/HystrixCommandMetrics.java

Lines 201 to 205 in 809104c

	/* package */ synchronized void resetStream() {
	healthCountsStream.unsubscribe();
	HealthCountsStream.removeByKey(key);
	healthCountsStream = HealthCountsStream.getInstance(key, properties);
	}

Hystrix/hystrix-core/src/main/java/com/netflix/hystrix/metric/consumer/BucketedCounterStream.java

Lines 85 to 96 in 809104c

	public void startCachingStreamValuesIfUnstarted() {
	if (subscription.get() == null) {
	//the stream is not yet started
	Subscription candidateSubscription = observe().subscribe(counterSubject);
	if (subscription.compareAndSet(null, candidateSubscription)) {
	//won the race to set the subscription
	} else {
	//lost the race to set the subscription, so we need to cancel this one
	candidateSubscription.unsubscribe();
	}
	}
	}