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From Richard Liang <richard.lian...@gmail.com>
Subject Re: [classlib][nio] [question] Synchronization issue on MappedByteBuffer ?
Date Mon, 03 Jul 2006 05:32:00 GMT
Hello Andrew,

IMHO, if the spec does not require a class thread-safe explicitly, we 
may regard the class as thread-unsafe.  Correct me if I'm wrong ;-) 

Andrew Zhang wrote:
> Hello everyone,
>
> I noticed there are several FIXMEs in MappedByteBufferAdapter.java, which
> are related to synchronization issue.
>
> Following FIXME is for getChar() method:
>
> // FIXME Need synchronization as far as the update of this.position is
> concerned of the following methods? Spec does not say whether
> MappedByteBuffer is thread safe. It is the decision we should make.
>
> I read through MappedByteBuffer javadoc, and didn't find any description
> about concurrent & synchronization. The spec on MappedByteBuffer 
> emphasizes
> "All or part of a mapped byte buffer may become inaccessible at any 
> time",
> and in the end, it mentions "Mapped byte buffers otherwise behave no
> differently than ordinary direct byte buffers."
>
> Spec doesn't mention any synchronization issues on direct byte buffers
> either. Therefore, in my opnion, only synchronizing for 
> MappedByteBuffer is
> unnecessary.
>
> Any comments? or may I miss something? Thanks!
>
> Best regards,
>
>

-- 
Richard Liang
China Software Development Lab, IBM 



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