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