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From "Marc Layer (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CXF-6674) Infinite loop when handling SOAP responses in split/parallel Camel route
Date Thu, 10 Mar 2016 08:38:40 GMT

    [ https://issues.apache.org/jira/browse/CXF-6674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15188914#comment-15188914
] 

Marc Layer commented on CXF-6674:
---------------------------------

After disabling the parallel processing feature, the problem has not recurred so far in our
production environment. (There was, however, also a change in the Dynatrace instrumentation
which might have brought in additional synchronizations that may have helped to suppress the
problem for now.)

Still, the busy loop in WrappedMessageContext.copyScoped() to me seems to be an indicator
that there is a slumbering thread synchronization issue somewhere in the context handling
code. Does this ring a bell with somebody? Any help would be appreciated!

> Infinite loop when handling SOAP responses in split/parallel Camel route
> ------------------------------------------------------------------------
>
>                 Key: CXF-6674
>                 URL: https://issues.apache.org/jira/browse/CXF-6674
>             Project: CXF
>          Issue Type: Bug
>          Components: JAX-WS Runtime
>    Affects Versions: 2.7.10
>         Environment: Apache Camel
> 2.12.3
> Apache CXF
> 2.7.10
> App Server
> WebSphere Platform 8.0.0.10 [ND 8.0.0.10 cf101502.03]
> Java Runtime Version
> pxa6460_26sr8fp2ifx-20141114_01 (SR8 FP2)
> Java Vendor
> IBM Corporation
> Java Version
> 1.6.0
> Java Compiler
> j9jit26
> Java VM name
> IBM J9 VM
> Operating System
> Linux
> OS Architecture
> x86_64
> OS Version
> 2.6.32-279.el6.x86_64
> VM Information
> JRE 1.6.0 Linux amd64-64 Compressed References 20141114_222464 (JIT enabled, AOT enabled)
> J9VM - R26_Java626_SR8_20141114_1023_B222464
> JIT  - r11.b07_20141003_74578.01
> GC   - R26_Java626_SR8_20141114_1023_B222464_CMPRSS
> J9CL - 20141114_222464
> VM Vendor
> IBM Corporation
> VM Version
> 2.6
>            Reporter: Marc Layer
>         Attachments: BackendServiceRoute.java, dynatrace.png
>
>
> We are using Apache Camel 2.12.3 and Apache CXF 2.7.10 to integrate some backend SOAP
web services. In our production environment we are facing the issue that at irregular intervals
a CXF worker thread would hang in a busy loop, consuming 100% CPU time. The only recovery
so far is to restart the server.
> The loop seems to occur in org.apache.cxf.jaxws.context.WrappedMessageContext.copyScoped():
> {noformat}
> 	private void copyScoped(Map<String, Object> msg) {
> 		for (String s : scopes.keySet()) {
> 			message.put(s, msg.get(s));
> 		}
> 	}
> {noformat}
> I guess it might be related to a threading issue that causes the iterator of scopes.keySet()
to loop infinitely. Using the VM monitoring tool Dynatrace, I can see that the iterated "scope"
map is an unsynchronized HashMap. I am unsure where the "scope" map was created and how it
could have leaked into another thread. "message" seems to be an instance of MessageImpl, which
is also derived from HashMap and therefore unsynchronized. I attached a Dynatrace screenshot
from one such invocation.
> Multi-threading in our case is two-fold:
> - CXF seems to be using separate worker threads even for synchronous invocations.
> - Additionally the call in question makes use of Camel's splitter EIP with parallel processing
which also uses separate threads (RouteBuilder is attached), effectively like this:
> {noformat}
> 	.split(body(), dataAggregator)
> 		.stopOnException()
> 		.parallelProcessing().executorServiceRef("multicastExecutorService")
> 		.to("cxf:bean:backendService")
> {noformat}
> I analyzed a number of cases in which two web service calls were dispatched at the same
time. Dynatrace shows that the backend web services always finished within about 80-130ms.
> Unfortunately we were unable to reproduce the error on a testing system where we could
have attached a remote debugger to the application, not even under heavy load. It only occured
in the production environment so far. Therefore I am uncertain if the problem only occurs
when Camel's parallelProcessing() is used. We will disable this feature in the application's
next release (end of next week) to verify this.
> There was another issue, CXF-6160 "AsyncResponse infinite loops", in which an infinite
loop in MessageImpl was tackled by making ExchangeImpl a subclass of ConcurrentHashMap rather
than a subclass of StringImpl (which is also derived from HashMap). Maybe these issues are
related. The fix, however, was implemented only for CXF 3.x. Unfortunately we are bound to
using Java 1.6 as Websphere 8 is only available for IBM JRE 1.6. The latest Camel version
available for Java 1.6 comes with CXF 2.7.14, later Camel versions are only available for
Java 1.7. I think we could easily upgrade to a newer 2.7.x version of CXF but not to CXF 3.x.



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