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https://issues.apache.org/jira/browse/GROOVY-7407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15927609#comment-15927609
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Jex Jexler commented on GROOVY-7407:
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I will most likely still try to find the issue in Ivy, but since Ivy is not
really actively developed any more and since making GrapeIvy sort of reliably
thread-safe seems rather a complex matter (both in Groovy/Grape and Ivy), how
about at least also adding a system property to Groovy that would allow to
optionally synchronize calls to GrapeIvy?
{{groovy.grape.synchronize}}
Possible values:
* {{false}} (default): No synchronization, same as now
* {{true}}: Lock on groovy.grape.GrapeIvy.class
* {{<class name>}}: Load the indicated class by name and use it as the lock
> 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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