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https://issues.apache.org/jira/browse/HDFS-17337?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shuyan Zhang resolved HDFS-17337.
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Fix Version/s: 3.4.0
Hadoop Flags: Reviewed
Target Version/s: 3.4.0 (was: 3.5.0)
Resolution: Fixed
> RPC RESPONSE time seems not exactly accurate when using FSEditLogAsync.
> -----------------------------------------------------------------------
>
> Key: HDFS-17337
> URL: https://issues.apache.org/jira/browse/HDFS-17337
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 3.3.6
> Reporter: farmmamba
> Assignee: farmmamba
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.4.0
>
>
> Currently, FSEditLogAsync is enabled by default.
> We have below codes in method Server$RpcCall#run:
>
> {code:java}
> if (!isResponseDeferred()) {
> long deltaNanos = Time.monotonicNowNanos() - startNanos;
> ProcessingDetails details = getProcessingDetails();
> details.set(Timing.PROCESSING, deltaNanos, TimeUnit.NANOSECONDS);
> deltaNanos -= details.get(Timing.LOCKWAIT, TimeUnit.NANOSECONDS);
> deltaNanos -= details.get(Timing.LOCKSHARED, TimeUnit.NANOSECONDS);
> deltaNanos -= details.get(Timing.LOCKEXCLUSIVE, TimeUnit.NANOSECONDS);
> details.set(Timing.LOCKFREE, deltaNanos, TimeUnit.NANOSECONDS);
> startNanos = Time.monotonicNowNanos();
> setResponseFields(value, responseParams);
> sendResponse();
> deltaNanos = Time.monotonicNowNanos() - startNanos;
> details.set(Timing.RESPONSE, deltaNanos, TimeUnit.NANOSECONDS);
> } else {
> if (LOG.isDebugEnabled()) {
> LOG.debug("Deferring response for callId: " + this.callId);
> }
> }{code}
> It computes Timing.RESPONSE of a RpcCall using *Time.monotonicNowNanos() -
> startNanos;*
> However, if we use async editlogging, we will not send response here but in
> FSEditLogAsync.RpcEdit#logSyncNotify.
> This causes the Timing.RESPONSE of a RpcCall not be exactly accurate.
> {code:java}
> @Override
> public void logSyncNotify(RuntimeException syncEx) {
> try {
> if (syncEx == null) {
> call.sendResponse();
> } else {
> call.abortResponse(syncEx);
> }
> } catch (Exception e) {} // don't care if not sent.
> } {code}
>
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