Potential for deadlock while using a ThrottlingHttpServiceHandler and a
SSLIOSession
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Key: HTTPCORE-130
URL: https://issues.apache.org/jira/browse/HTTPCORE-130
Project: HttpComponents Core
Issue Type: Bug
Components: HttpCore
Affects Versions: 4.0-alpha6
Environment: Linux RHEL 4, jdk 1.6_02
Reporter: Lorenzo Moretti
Fix For: 4.0-beta1
The following message was originally posted under HTTPCORE-48 but Oleg asked to
created a new issue for it.
I have been working with HttpCore alpha 6 for the past weeks and recently ran
into a deadlock. Since I am quite new to both NIO and SSL it might very well be
that the code for my tests is inappropriate. I obtained the following deadlock
stack trace using "kill -QUIT" on the process.
After the deadlock description I have very briefly explained what my test
methods do. I am not sure they are relevant since they do not do any locking
themselves, but *that* in itself might be the source of the problem! :)
Object <0x8c65a988>, if I am not mistaken, is the SharedInputBuffer.mutex.
Thread "RequestWorker_12" was spawned within
ThrottlingHttpServiceHandler.handleRequest() by this.executor.execute().
Thread "TestService_IOD_11" was spawned within
AbstractMultiworkerIOReactor.execute() by this.threadFactory.newThread()
=============================
"RequestWorker_12":
waiting to lock monitor 0x08083ac8 (object 0x8c61cd18, a
org.apache.http.impl.nio.reactor.SSLIOSession),
which is held by "TestService_IOD_11"
"TestService_IOD_11":
waiting to lock monitor 0x08083a64 (object 0x8c65a988, a java.lang.Object),
which is held by "RequestWorker_12"
Java stack information for the threads listed above:
===================================================
"RequestWorker_12":
at
org.apache.http.impl.nio.reactor.SSLIOSession.setEvent(SSLIOSession.java:371)
- waiting to lock <0x8c61cd18> (a
org.apache.http.impl.nio.reactor.SSLIOSession)
at
org.apache.http.impl.nio.NHttpConnectionBase.requestInput(NHttpConnectionBase.java:154)
at
org.apache.http.nio.util.SharedInputBuffer.waitForData(SharedInputBuffer.java:104)
- locked <0x8c65a988> (a java.lang.Object)
at
org.apache.http.nio.util.SharedInputBuffer.read(SharedInputBuffer.java:137)
- locked <0x8c65a988> (a java.lang.Object)
at
org.apache.http.nio.entity.ContentInputStream.read(ContentInputStream.java:63)
at TestHttpServer.readData(TestHttpServer.java:451)
at TestHttpServer.access$200(TestHttpServer.java:62)
at TestHttpServer$TestHandler3.handle(TestHttpServer.java:312)
at
org.apache.http.nio.protocol.ThrottlingHttpServiceHandler.handleRequest(ThrottlingHttpServiceHandler.java:477)
at
org.apache.http.nio.protocol.ThrottlingHttpServiceHandler.access$000(ThrottlingHttpServiceHandler.java:91)
at
org.apache.http.nio.protocol.ThrottlingHttpServiceHandler$1.run(ThrottlingHttpServiceHandler.java:195)
at java.lang.Thread.run(Thread.java:619)
at DefaultRequestExecutor$Worker.run(DefaultRequestExecutor.java:43)
"TestService_IOD_11":
at
org.apache.http.nio.util.SharedInputBuffer.consumeContent(SharedInputBuffer.java:71)
- waiting to lock <0x8c65a988> (a java.lang.Object)
at
org.apache.http.nio.protocol.ThrottlingHttpServiceHandler.inputReady(ThrottlingHttpServiceHandler.java:227)
- locked <0x8c658408> (a
org.apache.http.nio.protocol.ThrottlingHttpServiceHandler$ServerConnState)
at
org.apache.http.impl.nio.DefaultNHttpServerConnection.consumeInput(DefaultNHttpServerConnection.java:135)
at
org.apache.http.impl.nio.reactor.SSLServerIOEventDispatch.inputReady(SSLServerIOEventDispatch.java:132)
- locked <0x8c61cd18> (a org.apache.http.impl.nio.reactor.SSLIOSession)
at IoEventDispatchWrapper.inputReady(IoEventDispatchWrapper.java:45)
at
org.apache.http.impl.nio.reactor.BaseIOReactor.validate(BaseIOReactor.java:137)
at
org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:141)
at
org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:69)
at
org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:281)
at DebugThreadFactory$1.run(DebugThreadFactory.java:29)
at java.lang.Thread.run(Thread.java:619)
Found 1 deadlock.
RequestWorker_12 uses:
* DefaultRequestExecutor$Worker.run(): runs the Runnable created by
ThrottlingHttpServiceHandler.requestReceived().
* TestHttpServer$TestHandler3.handle(): acts as an echo by setting the response
body with the contents of the request body (status is set to SC_OK).
* TestHttpServer.readData(): transfers bytes from an
HttpEntityEnclosingRequest.getEntity().getContent() to a ByteArrayOutputStream.
DebugThreadFactory$1is a dynamically created Thread based on the Runnable
passed to ThreadFactory.newThread().
TestService_IOD_11 uses:
* DebugThreadFactory$1.run(): sets logging information before invoking
Runnable.run().
* IoEventDispatchWrapper.inputReady(): invokes the IOEventDispatch.inputReady()
for the dispatch it wraps.
Thanks for your time,
-- Lorenzo
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