harmony-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jesse Wilson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-6312) Concurrency problems in NIO
Date Tue, 13 Oct 2009 20:47:32 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-6312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12765226#action_12765226
] 

Jesse Wilson commented on HARMONY-6312:
---------------------------------------

Thanks Regis!

Some minor comments on the update:
 - the keys array should probably be of type SelectionKeyImpl
 - the comment on SelectorImpl line 597 is out of date

Regardless of what approach Harmony uses, from my investigation I'm confident that maintaining
indices to save HashSet iterations isn't appropriate for Android. I hope you'll come to the
same conclusion after your investigation.

> 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

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message