[jira] [Commented] (CXF-7784) java.util.ConcurrentModificationException on WebTarget.request()

["Andriy Redko (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CXF-7784?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16535960#comment-16535960 ] 

Andriy Redko commented on CXF-7784:
-----------------------------------

Hi [~dschmoigl],

The JAX-RS 2.x specification says nothing about thread safety of the Client API so it really runs down to be implementation-specific subject. With respect to CXF, the client APIs are **not thread-safe** by default: [http://cxf.apache.org/docs/jax-rs-client-api.html#JAX-RSClientAPI-ThreadSafety.] Hope it helps, thanks!

Best Regards,

    Andriy Redko

> java.util.ConcurrentModificationException on WebTarget.request()
> ----------------------------------------------------------------
>
>                 Key: CXF-7784
>                 URL: https://issues.apache.org/jira/browse/CXF-7784
>             Project: CXF
>          Issue Type: Bug
>          Components: JAX-RS
>    Affects Versions: 3.1.14
>         Environment: * Hystrix 1.5.9
>  * Spring-Boot 1.5.14
>  * JAXRS 3.1.14
>            Reporter: Dominic Schmoigl
>            Priority: Minor
>              Labels: cxf-rt-frontend-jaxrs
>
> By chance we stumbled over a case, where calling
> {code:java}
> webTarget.request(){code}
> sometimes may lead to a {{java.util.ConcurrentModificationException}}, if the {{webTarget}} is created in one thread, but the call to {{.request()}} is performed in multiple concurrent threads afterwards. In our environment it was possible provoke the exception with probability of ~10% if run with 4 threads in parallel.
> The callstack which we could isolate was:
> {code:java}
> Caused by: java.util.ConcurrentModificationException
>  at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
>  at java.util.ArrayList$Itr.next(ArrayList.java:859)
>  at org.apache.cxf.jaxrs.provider.ProviderFactory.injectContextProxies(ProviderFactory.java:638)
>  at org.apache.cxf.jaxrs.provider.ProviderFactory.setCommonProviders(ProviderFactory.java:600)
>  at org.apache.cxf.jaxrs.client.ClientProviderFactory.setProviders(ClientProviderFactory.java:74)
>  at org.apache.cxf.jaxrs.provider.ProviderFactory.setUserProviders(ProviderFactory.java:791)
>  at org.apache.cxf.jaxrs.client.spec.ClientImpl$WebTargetImpl.request(ClientImpl.java:282)
>  at <<custom-coding-which-calls-webTarget.request()>>
> {code}
> We currently have a workaround with
> {code:java}
> synchronized (webTarget) {
>    webTarget.request();
> }
> {code}
> which isn't perfect, but good enough in our case.
>  
> Is this case known to you? We did not try to reproduce the issue in isolation, yet (as it was hard enough to find it in our application already). If we should give it a try, please notify us.



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