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.
