[jira] [Comment Edited] (BCEL-267) Race conditions on static fields in BranchHandle and InstructionHandle

["Stephan Herrmann (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BCEL-267?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16755418#comment-16755418 ] 

Stephan Herrmann edited comment on BCEL-267 at 1/29/19 10:03 PM:
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{quote}[ANNOUNCEMENT] Apache Commons BCEL 6.3 Released
{quote}
 

Still no committer accepts the fact that a bug exists, for which fix & test have been submitted years ago? What else do you need?

C'mon guys, open source can do better than just hand waving and shrugging the issue off, which effectively prohibits the use of BCEL for load time transformers.


was (Author: sherrmann):
{quote}[ANNOUNCEMENT] Apache Commons BCEL 6.3 Released\{quote}

Still no committer accepts the fact that a bug exists, for which fix & test have been submitted years ago? What else do you need?

C'mon guys, open source can do better than just hand waving and shrugging the issue off, which effectively prohibits the use of BCEL for load time transformers.

> Race conditions on static fields in BranchHandle and InstructionHandle
> ----------------------------------------------------------------------
>
>                 Key: BCEL-267
>                 URL: https://issues.apache.org/jira/browse/BCEL-267
>             Project: Commons BCEL
>          Issue Type: Bug
>          Components: Main
>    Affects Versions: 5.2
>            Reporter: Stephan Herrmann
>            Priority: Major
>         Attachments: BCEL267--Race-conditions-on-static-fields-in-BranchH.patch
>
>
> I have observed race conditions causing NullPointerException like this
> {code}java.lang.NullPointerException
>         at org.apache.bcel.generic.InstructionList.getInstructionHandles(InstructionList.java:1021)
>         at org.apache.bcel.generic.InstructionList.findHandle(InstructionList.java:141)
>         at org.apache.bcel.generic.MethodGen.<init>(MethodGen.java:194)
> {code}
> In the debugger I could verify that concurrent access to the fields {{BranchHandle.bh_list}} or {{InstructionHandle.ih_list}} can cause corruption of those lists.
> I succeeded to make the exception less frequent by adding synchronized blocks, but still the exception could be observed. I concluded that for safe protection the fields would need to be made volatile, which in the end might actually defeat their original purpose of optimization.
> I have since then run with a patched version of BCEL, where those static fields were simply removed and new Handles were created on every request. This variant finally was free of the race condition.
> Seeing activity towards a 6.0 release, I'd appreciate if this change could be incorporated.
> The original bug tracking my experiments can be found in Eclipse bugzilla: https://bugs.eclipse.org/344350
> The modified classes (based on 5.2) can be found here:
> - http://git.eclipse.org/c/objectteams/org.eclipse.objectteams.git/tree/plugins/org.eclipse.objectteams.otre/bcelpatchsrc/org/apache/bcel/generic



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