[jira] Closed: (HARMONY-6312) Concurrency problems in NIO

["Jesse Wilson (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HARMONY-6312?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jesse Wilson closed HARMONY-6312.
---------------------------------

    Resolution: Fixed

Looks Good To Me. 

I still think the performance benefits of the indices won't hold up on a proper benchmark, but that's a separate problem. My concurrency concerns have all been addressed, so I'm closing this issue.

Thanks Regis!

> Concurrency problems in NIO
> ---------------------------
>
>                 Key: HARMONY-6312
>                 URL: https://issues.apache.org/jira/browse/HARMONY-6312
>             Project: Harmony
>          Issue Type: Bug
>          Components: Classlib
>         Environment: SVN Revision: 801399
>            Reporter: Jesse Wilson
>            Assignee: Regis Xu
>         Attachments: cancelledkey.diff, harmony_svn.html, harmony_svn_plus_patch_2009-08-19.html, NIO_Concurrency_issues.patch, NIO_Concurrency_issues_2.patch, ri.html, selector.zip, SelectorBenchmark.java
>
>   Original Estimate: 72h
>  Remaining Estimate: 72h
>
> There's several potential concurrency problems in our NIO implementation...
>  - Charset#isSupported isn't synchronized, but it accesses mutable member cachedCharsetTable.
>  - In SelectionKeyImpl, stHash++ is a non-atomic operation so multiple SelectionKey instances may receive the same hash code. (Why not use the default hash code?)
>  - In SelectorImpl, the unmodifiableKeys member is never synchronized on. But the documentation specifies that clients can synchronize on that set to guard against changes
> These are the obvious problems; I suspect there are more subtle concurrency defects at play here. I'll prepare a patch to address the major issues, and we should consider a rigorous approach (Findbugs?) to discover concurrency problems.
> #Android

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