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Date: Thu, 18 Aug 2011 18:02:30 -0700
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Subject: Re: help with CommitLog code?
From: Yang <teddyyyy123@gmail.com>
To: user@cassandra.apache.org
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thanks Jonathan, found it


    public BatchCommitLogExecutorService(int queueSize)
    {
        queue =3D new LinkedBlockingQueue<CheaterFutureTask>(queueSize);
        ...........
        appendingThread =3D new Thread(runnable, "COMMIT-LOG-WRITER");
        appendingThread.start();

    }

On Thu, Aug 18, 2011 at 5:58 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
> There is always a single CLES thread whether for Batch or Periodic.
> (For Batch, look for the appendingThread field.)
>
> On Thu, Aug 18, 2011 at 7:41 PM, Yang <teddyyyy123@gmail.com> wrote:
>> I'm reading the commitLog code since I have some similar logic in my
>> application code,
>> so that I could benefit from the same techniques that CommitLog code use=
s.
>>
>> I see that
>> CommitLog.add(RowMutation rowMutation) {
>> =A0 =A0 =A0 =A0executor.add(new LogRecordAdder(rowMutation));
>> }
>>
>> while executor could be the parallel =A0BatchCommitLogExecutorService(),
>> which by default
>> has 32 writer threads.
>>
>> I wonder how the CommitLog code is able to avoid writing garbled
>> result on the file,
>> since if multiple LogRecordAdder() are all executed at the same time, =
=A0they run
>> currentSegment().write() =3D=3D=3D=3D> SequentialWriter.write() , is it
>> possible that their output will overlap??
>>
>>
>> Thanks =A0l lot
>> Yang
>>
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support
> http://www.datastax.com
>