[jira] [Commented] (GROOVY-7407) Compilation not thread safe if Grape / Ivy is used in Groovy scripts

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[jira] [Commented] (GROOVY-7407) Compilation not thread safe if Grape / Ivy is used in Groovy scripts

JIRA jira@apache.org

    [ https://issues.apache.org/jira/browse/GROOVY-7407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15927585#comment-15927585 ]

Jex Jexler commented on GROOVY-7407:
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*Side remark:* GrapeIvy seems not to be designed for use by separate threads; grab(..) and resolve(..) and other public methods modify instance variables like (unsynchronized) lists etc. This has not caused any problems in my tests (so far still looks like the origin would rather be in Ivy than in Groovy/Grape), but currently I would generally recommend to synchronize calls to GrapeIvy if you want to be safe (see the attached Workaround*.java or use Grengine.Grape.activate(..), which are both also viable workarounds for this issue, with the drawback that other threads have to wait when an artifact is downloaded).

> Compilation not thread safe if Grape / Ivy is used in Groovy scripts
> --------------------------------------------------------------------
>
>                 Key: GROOVY-7407
>                 URL: https://issues.apache.org/jira/browse/GROOVY-7407
>             Project: Groovy
>          Issue Type: Bug
>          Components: Compiler, Grape
>    Affects Versions: 2.4.3
>         Environment: Essentially independent of the environment, as long as Groovy scripts use Grape; also this bug seems to be present since at least Groovy 1.7.5.
>            Reporter: Jex Jexler
>            Priority: Minor
>              Labels: Compile, Grape, Groovy, Ivy
>         Attachments: GrabConcurrencyTest.java, GrapeAndGroovyShellConcurrencyTest.java, GroovyCompileConcurrencyTest.java, stacktrace-GrapeAndGroovyShellConcurrencyTest-1.txt, stacktrace-GrapeAndGroovyShellConcurrencyTest-2.txt, stacktrace-GroovyCompileConcurrencyTest-1.txt, stacktrace-GroovyCompileConcurrencyTest-2.txt, WorkaroundGroovy7407WrappingGrapeEngine.java
>
>
> If Groovy scripts that import the same libraries via Grape are compiled in separate threads, compilation may fail due to race conditions.
> This does not happen if several threads use the *same* instance of GroovyClassLoader (GCL), because parseClass() uses synchronization.
> But as soon as different GCLs are used in separate threads or if the compiler is used directly (CompilationUnit.compile()), the issue occurs and compilation can fail.
> Two Java unit tests have be attached, which reproduce the issue, although this cannot be guaranteed with 100% certainty, because there is a race condition.
> Two different stacktraces have been observed for each unit test (with origins in Grape and in Ivy), which have also been attached (plus in a different environment (Tomcat webapp CentOS) once a an exception down in Ivy had been observed that seemed to be related to unzipping a JAR file, but no precise record of that exists any more).



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