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From Tim Ellison <t.p.elli...@gmail.com>
Subject Re: [classlib][nio] [question] Synchronization issue on MappedByteBuffer ?
Date Mon, 03 Jul 2006 10:02:54 GMT
Richard Liang wrote:
> 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 ;-)

I agree -- you may assume unsafe unless spec'd otherwise.

Regards,
Tim

> 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,
>>
>>
> 

-- 

Tim Ellison (t.p.ellison@gmail.com)
IBM Java technology centre, UK.

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