java 11 HttpClient leads to endless SSL loop

Question

I am using the new java.net.http.HttpClient with the sendAsync method. The HttpClient is inside a Singelton and is created once like so: HttpClient.newBuilder().build() so really nothing special.

Those requests can be POST or GET but I don't know which causes the trouble.

There are just a few requests a day but from time to time one thread uses 100% of a cpu core. And not imminently but after some time when the request has finished.

So I did a thread dump when there were even 2 of those endless loops occurring, the following 2 threads stood out:

"HttpClient-4-Worker-5" #144 daemon prio=5 os_prio=0 cpu=511298.10ms elapsed=520.71s tid=0x00007f684403e800 nid=0x2d6b runnable  [0x00007f68ac162000]    java.lang.Thread.State: RUNNABLE         at jdk.internal.net.http.common.SSLFlowDelegate$Writer.processData([email protected]/SSLFlowDelegate.java:771)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer$WriterDownstreamPusher.run([email protected]/SSLFlowDelegate.java:645)         at jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run([email protected]/SequentialScheduler.java:147)         at jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run([email protected]/SequentialScheduler.java:198)         at jdk.internal.net.http.common.SequentialScheduler.runOrSchedule([email protected]/SequentialScheduler.java:271)         at jdk.internal.net.http.common.SequentialScheduler.runOrSchedule([email protected]/SequentialScheduler.java:224)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer.triggerWrite([email protected]/SSLFlowDelegate.java:722)         at jdk.internal.net.http.common.SSLFlowDelegate.doHandshake([email protected]/SSLFlowDelegate.java:1024)         at jdk.internal.net.http.common.SSLFlowDelegate.doClosure([email protected]/SSLFlowDelegate.java:1094)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader.unwrapBuffer([email protected]/SSLFlowDelegate.java:500)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader.processData([email protected]/SSLFlowDelegate.java:389)         - locked <0x00000000fba68950> (a java.lang.Object)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader$ReaderDownstreamPusher.run([email protected]/SSLFlowDelegate.java:263)         at jdk.internal.net.http.common.SequentialScheduler$SynchronizedRestartableTask.run([email protected]/SequentialScheduler.java:175)         - locked <0x00000000fbbca3e8> (a java.lang.Object)         at jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run([email protected]/SequentialScheduler.java:147)         at jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run([email protected]/SequentialScheduler.java:198)         at java.util.concurrent.ThreadPoolExecutor.runWorker([email protected]/ThreadPoolExecutor.java:1128)         at java.util.concurrent.ThreadPoolExecutor$Worker.run([email protected]/ThreadPoolExecutor.java:628)         at java.lang.Thread.run([email protected]/Thread.java:834)     Locked ownable synchronizers:         - <0x00000000fc1ff920> (a java.util.concurrent.ThreadPoolExecutor$Worker)      "HttpClient-4-Worker-2" #82 daemon prio=5 os_prio=0 cpu=4266156.67ms elapsed=4311.42s tid=0x00007f6844007000 nid=0x29ee runnable  [0x00007f686fffd000]    java.lang.Thread.State: RUNNABLE         at jdk.internal.net.http.common.SSLFlowDelegate$Writer.processData([email protected]/SSLFlowDelegate.java:771)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer$WriterDownstreamPusher.run([email protected]/SSLFlowDelegate.java:645)         at jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run([email protected]/SequentialScheduler.java:147)         at jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run([email protected]/SequentialScheduler.java:198)         at jdk.internal.net.http.common.SequentialScheduler.runOrSchedule([email protected]/SequentialScheduler.java:271)         at jdk.internal.net.http.common.SequentialScheduler.runOrSchedule([email protected]/SequentialScheduler.java:224)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer.triggerWrite([email protected]/SSLFlowDelegate.java:722)         at jdk.internal.net.http.common.SSLFlowDelegate.doHandshake([email protected]/SSLFlowDelegate.java:1024)         at jdk.internal.net.http.common.SSLFlowDelegate.doClosure([email protected]/SSLFlowDelegate.java:1094)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader.unwrapBuffer([email protected]/SSLFlowDelegate.java:500)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader.processData([email protected]/SSLFlowDelegate.java:389)         - locked <0x00000000f97668d0> (a java.lang.Object)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader$ReaderDownstreamPusher.run([email protected]/SSLFlowDelegate.java:263)         at jdk.internal.net.http.common.SequentialScheduler$SynchronizedRestartableTask.run([email protected]/SequentialScheduler.java:175)         - locked <0x00000000f97668f0> (a java.lang.Object)         at jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run([email protected]/SequentialScheduler.java:147)         at jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run([email protected]/SequentialScheduler.java:198)         at java.util.concurrent.ThreadPoolExecutor.runWorker([email protected]/ThreadPoolExecutor.java:1128)         at java.util.concurrent.ThreadPoolExecutor$Worker.run([email protected]/ThreadPoolExecutor.java:628)         at java.lang.Thread.run([email protected]/Thread.java:834)     Locked ownable synchronizers:         - <0x00000000f9894cc0> (a java.util.concurrent.ThreadPoolExecutor$Worker) 

Same observation but on another container where only one thread was affected.

"HttpClient-3-Worker-2" #120 daemon prio=5 os_prio=0 cpu=1100568.51ms elapsed=1113.79s tid=0x00007eff3003b800 nid=0x479 runnable  [0x00007eff83bf8000]    java.lang.Thread.State: RUNNABLE         at sun.security.ssl.SSLEngineImpl.wrap([email protected]/SSLEngineImpl.java:136)         - eliminated <0x00000000f9796e08> (a sun.security.ssl.SSLEngineImpl)         at sun.security.ssl.SSLEngineImpl.wrap([email protected]/SSLEngineImpl.java:116)         - locked <0x00000000f9796e08> (a sun.security.ssl.SSLEngineImpl)         at javax.net.ssl.SSLEngine.wrap([email protected]/SSLEngine.java:519)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer.wrapBuffers([email protected]/SSLFlowDelegate.java:821)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer.processData([email protected]/SSLFlowDelegate.java:736)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer$WriterDownstreamPusher.run([email protected]/SSLFlowDelegate.java:645)         at jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run([email protected]/SequentialScheduler.java:147)         at jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run([email protected]/SequentialScheduler.java:198)         at jdk.internal.net.http.common.SequentialScheduler.runOrSchedule([email protected]/SequentialScheduler.java:271)         at jdk.internal.net.http.common.SequentialScheduler.runOrSchedule([email protected]/SequentialScheduler.java:224)         at jdk.internal.net.http.common.SSLFlowDelegate$Writer.triggerWrite([email protected]/SSLFlowDelegate.java:722)         at jdk.internal.net.http.common.SSLFlowDelegate.doHandshake([email protected]/SSLFlowDelegate.java:1024)         at jdk.internal.net.http.common.SSLFlowDelegate.doClosure([email protected]/SSLFlowDelegate.java:1094)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader.unwrapBuffer([email protected]/SSLFlowDelegate.java:500)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader.processData([email protected]/SSLFlowDelegate.java:389)         - locked <0x00000000f9797010> (a java.lang.Object)         at jdk.internal.net.http.common.SSLFlowDelegate$Reader$ReaderDownstreamPusher.run([email protected]/SSLFlowDelegate.java:263)         at jdk.internal.net.http.common.SequentialScheduler$SynchronizedRestartableTask.run([email protected]/SequentialScheduler.java:175)         - locked <0x00000000f9797030> (a java.lang.Object)         at jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run([email protected]/SequentialScheduler.java:147)         at jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run([email protected]/SequentialScheduler.java:198)         at java.util.concurrent.ThreadPoolExecutor.runWorker([email protected]/ThreadPoolExecutor.java:1128)         at java.util.concurrent.ThreadPoolExecutor$Worker.run([email protected]/ThreadPoolExecutor.java:628)         at java.lang.Thread.run([email protected]/Thread.java:834) 

Some example code I am using

httpClient.sendAsync(request, HttpResponse.BodyHandlers.ofString())                                 .thenApply(logResponse()); 

Java Version

openjdk version "11.0.2" 2019-01-15 OpenJDK Runtime Environment (build 11.0.2+9-Debian-3) OpenJDK 64-Bit Server VM (build 11.0.2+9-Debian-3, mixed mode, sharing) 

The problem also occurs when preferring HTTP 2

Updates

Am I using the HttpClient in a wrong way? Could this be a Server Problem? Is it maybe this bug https://bugs.openjdk.java.net/browse/JDK-8207009?

• Client connects to a cloudflare service
• When the issue occurs there are is no open connection to cloudflare via netstat visible
• I can pin the problem to http2 + tlsv1.3 (using the nginx docker image: nginx:1.15-alpine with tls1.3 enabled of course)

Bug appears to be fixed now according to https://bugs.openjdk.java.net/browse/JDK-8241054

Answer 1

As @jspcal said before disable TLS 1.3.

tl;dr: disable tlsv1.3 via extending/overwriting

<java_home>/conf/security/java.security the jdk.tls.disabledAlgorithms property

Since my application is running in a docker container I changed the base image to disable tls1.3

FROM openjdk:11-jre ...  RUN sed -i "/jdk.tls.disabledAlgorithms=/ s/=.*/=TLSv1.3, SSLv3, RC4, MD5withRSA, DH keySize < 1024, EC keySize < 224, DES40_CBC, RC4_40, 3DES_EDE_CBC/" $(readlink -f /usr/bin/java | sed "s:bin/java::")/conf/security/java.security 

As far as I know there is no way of setting this (security) property via a system property! See also sun.security.util.DisabledAlgorithmConstraints#PROPERTY_TLS_DISABLED_ALGS which actually ready the property.

Update: Bug is still present in 11.0.2