Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@cassandra.apache.org
Received-SPF: pass (athena.apache.org: domain of zhuxq02@126.com designates
 220.181.15.3 as permitted sender)
Date: Sat, 8 Oct 2011 16:05:38 +0800 (CST)
From: hicks <zhuxq02@126.com>
To: user@cassandra.apache.org
Message-ID: <6c817eee.12c31.132e290e191.Coremail.zhuxq02@126.com>
Subject: i have a question about "commitlog_sync"
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_Part_209348_265681173.1318061138321"

------=_Part_209348_265681173.1318061138321
Content-Type: text/plain; charset=GBK
Content-Transfer-Encoding: 7bit

hi,all:
  i have a question about the option "commitlog_sync" in cassandra.yaml file.when its value is set to "batch",the ICommitLogExecutorService instance of CommitLog will be BatchCommitLogExecutorService in which there is a method named processWithSyncBatch.and in this method,there is a code segment:
        while (!queue.isEmpty()
               && queue.peek().getRawCallable() instanceof CommitLog.LogRecordAdder
               && System.nanoTime() < end)
        {
            CheaterFutureTask task = queue.remove();
            incompleteTasks.add(task);
            taskValues.add(task.getRawCallable().call());
        }
task.getRawCallable().call() will call CommitLog.LogRecordAdder.run()  which does the same thing as appendingThread in PeriodicCommitLogExecutorService. we can see the task in the queue is excecuted one by one,use logWriter to do the write operaton, finally do sync when the commitlog_sync_batch_window_in_ms is up or the queue has no task,just as PeriodicCommitLogExecutorService. i don't understand where reflect the conception of "batch"? or the question can be what is the difference between PeriodicCommitLogExecutorService and BatchCommitLogExecutorService?
   Be expectingyourresponse! Thks very much.
------=_Part_209348_265681173.1318061138321
Content-Type: text/html; charset=GBK
Content-Transfer-Encoding: 7bit

<div style="line-height:1.7;color:#000000;font-size:14px;font-family:arial"><DIV>
<DIV style="LINE-HEIGHT: 1.7; FONT-FAMILY: arial; COLOR: #000000; FONT-SIZE: 14px">
<DIV>
<DIV style="LINE-HEIGHT: 1.7; FONT-FAMILY: arial; COLOR: #000000; FONT-SIZE: 14px">
<DIV>hi,all:</DIV>
<DIV>&nbsp;&nbsp;i have a question about the option "commitlog_sync"&nbsp;in cassandra.yaml file.when its value is set to "batch",the ICommitLogExecutorService instance of CommitLog will be BatchCommitLogExecutorService in which there is a method named processWithSyncBatch.and in this method,there is a code segment:</DIV>
<DIV>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; while (!queue.isEmpty()<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &amp;&amp; queue.peek().getRawCallable() instanceof CommitLog.LogRecordAdder<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &amp;&amp; System.nanoTime() &lt; end)<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; CheaterFutureTask task = queue.remove();<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; incompleteTasks.add(task);<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; taskValues.add(task.getRawCallable().call());<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</DIV>
<DIV>task.getRawCallable().call()&nbsp;will call CommitLog.LogRecordAdder.run()&nbsp; which&nbsp;does the same thing as appendingThread in PeriodicCommitLogExecutorService. we can see the task in the queue is excecuted one by one,use logWriter to do the write operaton, finally do sync when the commitlog_sync_batch_window_in_ms is up or the queue has no task,just as PeriodicCommitLogExecutorService. i don't understand where reflect the conception of "batch"? or the question can be what is the difference between PeriodicCommitLogExecutorService and BatchCommitLogExecutorService?</DIV>
<DIV>&nbsp;&nbsp;&nbsp; <SPAN id="tran_2_0" on__mouseover="LjHighlightAlign('#src_2_0,#tran_2_0')" on__mouseout="LjUnhighlightAlign('#src_2_0,#tran_2_0')">Be expecting</SPAN> <SPAN id="tran_2_1" on__mouseover="LjHighlightAlign('#src_2_1,#tran_2_1')" on__mouseout="LjUnhighlightAlign('#src_2_1,#tran_2_1')">your</SPAN> <SPAN id="tran_2_2" class="highLight" on__mouseover="LjHighlightAlign('#src_2_2,#tran_2_2')" on__mouseout="LjUnhighlightAlign('#src_2_2,#tran_2_2')"><FONT style="BACKGROUND-COLOR: #d6ebf9">response</FONT></SPAN>! Thks very much.</DIV></DIV></DIV></DIV></DIV></div><br><br><span title="neteasefooter"><span id="netease_mail_footer"></span></span>
------=_Part_209348_265681173.1318061138321--