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MapReduce, mail # user - Why LineRecordWriter.write(..) is synchronized


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Re: Why LineRecordWriter.write(..) is synchronized
Niels Basjes 2013-08-08, 11:00
I may be nitpicking here but if "perhaps the answer is no" then I conclude:
Perhaps the other implementations of RecordWriter are a race condition/file
corruption ready to occur.
On Thu, Aug 8, 2013 at 12:50 PM, Harsh J <[EMAIL PROTECTED]> wrote:

> While we don't fork by default, we do provide a MultithreadedMapper
> implementation that would require such synchronization. But if you are
> asking is it necessary, then perhaps the answer is no.
> On Aug 8, 2013 3:43 PM, "Azuryy Yu" <[EMAIL PROTECTED]> wrote:
>
>> its not hadoop forked threads, we may create a line record writer, then
>> call this writer concurrently.
>> On Aug 8, 2013 4:00 PM, "Sathwik B P" <[EMAIL PROTECTED]> wrote:
>>
>>> Hi,
>>> Thanks for your reply.
>>> May I know where does hadoop fork multiple threads to use a single
>>> RecordWriter.
>>>
>>> regards,
>>> sathwik
>>>
>>> On Thu, Aug 8, 2013 at 7:06 AM, Azuryy Yu <[EMAIL PROTECTED]> wrote:
>>>
>>>> because we may use multi-threads to write a single file.
>>>> On Aug 8, 2013 2:54 PM, "Sathwik B P" <[EMAIL PROTECTED]> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> LineRecordWriter.write(..) is synchronized. I did not find any other
>>>>> RecordWriter implementations define the write as synchronized.
>>>>> Any specific reason for this.
>>>>>
>>>>> regards,
>>>>> sathwik
>>>>>
>>>>
>>>
--
Best regards / Met vriendelijke groeten,

Niels Basjes