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https://issues.apache.org/jira/browse/DIRECTMEMORY-137?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13871680#comment-13871680
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Christoph Engelbert edited comment on DIRECTMEMORY-137 at 1/15/14 5:48 AM:
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A MemoryBuffer (as most other buffer, stream implementations is not threadsafe
by design. It is meant to be fast and so synchronization is bad. The correct
way would be to duplicate the buffer to have it's own writer/reader index for
every access.
Let me think of this since that seems to be a general issue for all operations
inside the memorybuffer
was (Author: noctarius):
A MemoryBuffer (as most other buffer, stream implementations is not threadsafe
by design. It is meant to be fast and so synchronization is bad. The correct
way would be to duplicate the buffer to have it's own writer/reader index for
every access.
> Concurrent access to MemoryBuffer leads to BufferUnderflowException
> -------------------------------------------------------------------
>
> Key: DIRECTMEMORY-137
> URL: https://issues.apache.org/jira/browse/DIRECTMEMORY-137
> Project: Apache DirectMemory
> Issue Type: Bug
> Components: core
> Affects Versions: 0.2
> Reporter: Chetan Mehrotra
> Attachments: DIRECTMEMORY-137.patch
>
>
> When same MemoryBuffer is accessed by multiple thread concurrently then it
> can lead to BufferUnderflowException.
> MemoryManagerService.retrieve method performs following steps
> 1. Get MemoryBuffer associated with the Pointer
> 2. Set its readerIndex to 0
> 3. Call readBytes. Which for {{NioMemoryBuffer}} invokes following code
> @Override
> public int readBytes( byte[] bytes, int offset, int length )
> {
> byteBuffer.get( bytes, offset, length );
> readerIndex += length;
> return length;
> }
> So if multiple thread invoke retrieve with same Pointer then readerIndex
> might be set to wrong value leading to BufferUnderflowException
> Refer to [1] for details
> [1] http://markmail.org/thread/yvevhzddta2fyal6
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