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https://issues.apache.org/jira/browse/HBASE-14331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14740280#comment-14740280
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Hiroshi Ikeda commented on HBASE-14331:
---------------------------------------
That seems a mere bug.
AnnotationReadingPriorityFunction.getDeadline
{code}
public long getDeadline(RequestHeader header, Message param) {
String methodName = header.getMethodName();
if (methodName.equalsIgnoreCase("scan")) {
ScanRequest request = (ScanRequest)param;
if (!request.hasScannerId()) {
return 0;
}
// get the 'virtual time' of the scanner, and applies sqrt() to get a
// nice curve for the delay. More a scanner is used the less priority it
gets.
// The weight is used to have more control on the delay.
long vtime = rpcServices.getScannerVirtualTime(request.getScannerId());
return Math.round(Math.sqrt(vtime * scanVirtualTimeWeight));
}
return 0;
}
{code}
> long vtime = rpcServices.getScannerVirtualTime(request.getScannerId());
doesn't give the 'virtual time' for the request. That should be:
long vtime = request.getNextCallSeq();
And It is subtle but seems not to be changed. (But I also feel that method is
not so trivial to be frequently used in a comparator...)
> a single callQueue related improvements
> ---------------------------------------
>
> Key: HBASE-14331
> URL: https://issues.apache.org/jira/browse/HBASE-14331
> Project: HBase
> Issue Type: Improvement
> Components: IPC/RPC, Performance
> Reporter: Hiroshi Ikeda
> Assignee: Hiroshi Ikeda
> Priority: Minor
> Attachments: BlockingQueuesPerformanceTestApp-output.pdf,
> BlockingQueuesPerformanceTestApp-output.txt,
> BlockingQueuesPerformanceTestApp.java, CallQueuePerformanceTestApp.java,
> HBASE-14331-V2.patch, HBASE-14331-V3.patch, HBASE-14331.patch,
> HBASE-14331.patch, SemaphoreBasedBlockingQueue.java,
> SemaphoreBasedLinkedBlockingQueue.java,
> SemaphoreBasedPriorityBlockingQueue.java
>
>
> {{LinkedBlockingQueue}} well separates locks between the {{take}} method and
> the {{put}} method, but not between takers, and not between putters. These
> methods are implemented to take locks at the almost beginning of their logic.
> HBASE-11355 introduces multiple call-queues to reduce such possible
> congestion, but I doubt that it is required to stick to {{BlockingQueue}}.
> There are the other shortcomings of using {{BlockingQueue}}. When using
> multiple queues, since {{BlockingQueue}} blocks threads it is required to
> prepare enough threads for each queue. It is possible that there is a queue
> starving for threads while there is another queue where threads are idle.
> Even if you can tune parameters to avoid such situations, the tuning is not
> so trivial.
> I suggest using a single {{ConcurrentLinkedQueue}} with {{Semaphore}}.
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