Connection leaks in Zuul "post" filters

[denyska]

Poor written "post" Zuul filter might cause response input stream not being closed and connection leaks in respective http-client connection pools.

[denyska]

@dsyer @spencergibb I wonder if I should move fix to eitherZuulServlet#service(), either com.netflix.zuul.context.RequestContext#unset(). Ideally streams should be closed on the same layer they are opened, however in Route-Post filter chains it is hard to achieve.

[dsyer]

I get why you want to do this, but is there any proof that it's necessary? Something that is obviously broken without it? Otherwise I'm wondering whether maybe Netflix code covers this scenario already somewhere.

P.S. you probably need to rebase your branch and re-push to clean up the history.

[denyska]

@dsyer Zuul advocates writing custom filters and I assume a lot of people do it. In my case I have custom POST filter that massages response headers before they hit wire. Unfortunately I had sneaky NPE in that filter that was not logged (another topic to talk about, but Zuul logging has room to improve) and instead was masked with ConnectionPoolTimeoutException hundreds requests later.

at org.springframework.cloud.netflix.zuul.filters.route.apache.HttpClientRibbonCommand.run(HttpClientRibbonCommand.java:99)
    at org.springframework.cloud.netflix.zuul.filters.route.apache.HttpClientRibbonCommand.run(HttpClientRibbonCommand.java:43)
    at com.netflix.hystrix.HystrixCommand$1.call(HystrixCommand.java:293)
    at com.netflix.hystrix.HystrixCommand$1.call(HystrixCommand.java:289)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:46)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:50)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:50)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.Observable.unsafeSubscribe(Observable.java:8460)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:50)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:50)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.Observable.unsafeSubscribe(Observable.java:8460)
    at rx.internal.operators.OperatorSubscribeOn$1.call(OperatorSubscribeOn.java:94)
    at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction$1.call(HystrixContexSchedulerAction.java:56)
    at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction$1.call(HystrixContexSchedulerAction.java:47)
    at org.springframework.cloud.sleuth.instrument.hystrix.SleuthHystrixConcurrencyStrategy$HystrixTraceCallable.call(SleuthHystrixConcurrencyStrategy.java:140)
    at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction.call(HystrixContexSchedulerAction.java:69)
    at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    ... 1 common frames omitted
Caused by: java.lang.RuntimeException: org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection from pool
    at rx.observables.BlockingObservable.blockForSingle(BlockingObservable.java:456)
    at rx.observables.BlockingObservable.single(BlockingObservable.java:332)

[spencergibb]

Closing due to inactivity. Please re-open if there's more to discuss