[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=15923810#comment-15923810 ]

Jex Jexler commented on GROOVY-7407:
------------------------------------

The ConcurrentModificationException of stacktrace-GrapeAndGroovyShellConcurrencyTest-1.txt is because Ivy's MessageLoggerHelper is not thread-safe, it iterates over lists that can be modified during iteration by other threads, in the test cases iteration was over lists in MessageLoggerEngine. After wrapping the 3 member lists of MessageLoggerEngine with Collections.synchronizedList(...) and making copies before iterating over the lists in MessageLoggerHelper I get the following behavior: Both test cases log many messages "unknown resolver null" (which can a priori come from different places in Ivy) and the GroovyCompileConcurrencyTest so far always fails with the stacktrace-GroovyCompileConcurrencyTest-1.txt, i.e. it cannot resolve Guava's Ascii class, presumably because something else is not thread-safe. (After my changes I cannot reproduce exceptions in the other test, GrapeAndGroovyShellConcurrencyTest.java, anymore so far, so it appears as if the logged errors are not fatal.

> 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: 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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