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From "Gary Tully (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (AMQ-3982) Overlapping PList iterators can read wrong data or throw exceptions about chunk streams not existing.
Date Fri, 19 Oct 2012 22:52:13 GMT

     [ https://issues.apache.org/jira/browse/AMQ-3982?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gary Tully updated AMQ-3982:
----------------------------

    Comment: was deleted

(was: a variant of the concurrent add iterate test that fails.

Syncing all updates, seeks and writes in pagefile should resolve, but there is somehting more:
{code}
synchronized (this) {
  readFile.seek(toOffset(pageId))
  readFile.readFully(data);
}
...
synchronized (this) {
  writeFile.seek(toOffset(w.page.getPageId()));
  writeFile.write(w.getDiskBound(), 0, pageSize);
}{code})
    
> Overlapping PList iterators can read wrong data or throw exceptions about chunk streams
not existing.
> -----------------------------------------------------------------------------------------------------
>
>                 Key: AMQ-3982
>                 URL: https://issues.apache.org/jira/browse/AMQ-3982
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.6.0
>            Reporter: Timothy Bish
>            Assignee: Timothy Bish
>            Priority: Critical
>             Fix For: 5.7.0
>
>         Attachments: new.txt
>
>
> When multiple PList iterators are in use and happen have an overlapping read of PageFile
data on disk they can reset each others seek offset and cause an exception to be thrown about
"chunk stream does not exist" or read of a page in the Free list.  The reason is that the
hasNext of PList iterator needs to by sync'd on the index lock to prevent two iterators from
entering into a readPage call concurrently.  

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