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https://issues.apache.org/jira/browse/ZOOKEEPER-2770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16100940#comment-16100940
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ASF GitHub Bot commented on ZOOKEEPER-2770:
-------------------------------------------
Github user karanmehta93 commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/307#discussion_r129450258
--- Diff:
src/java/main/org/apache/zookeeper/server/quorum/QuorumPeerConfig.java ---
@@ -61,6 +61,7 @@
private static boolean standaloneEnabled = true;
private static boolean reconfigEnabled = false;
+ private static int requestWarnThresholdMs = 10000;
--- End diff --
To be frank, I am newbie and haven't debugged this in detail. This value is
purely seen based on the 'stat' command on our test cluster. @apurtell might be
able to tell more practical values.
@skamille I would prefer turning this on by default, although the default
value needs to be discussed. In my understanding, this helps in situations when
we see timeouts at application level, such a log can might help narrow down
towards the cause.
> ZooKeeper slow operation log
> ----------------------------
>
> Key: ZOOKEEPER-2770
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2770
> Project: ZooKeeper
> Issue Type: Improvement
> Reporter: Karan Mehta
> Assignee: Karan Mehta
> Attachments: ZOOKEEPER-2770.001.patch, ZOOKEEPER-2770.002.patch,
> ZOOKEEPER-2770.003.patch
>
>
> ZooKeeper is a complex distributed application. There are many reasons why
> any given read or write operation may become slow: a software bug, a protocol
> problem, a hardware issue with the commit log(s), a network issue. If the
> problem is constant it is trivial to come to an understanding of the cause.
> However in order to diagnose intermittent problems we often don't know where,
> or when, to begin looking. We need some sort of timestamped indication of the
> problem. Although ZooKeeper is not a datastore, it does persist data, and can
> suffer intermittent performance degradation, and should consider implementing
> a 'slow query' log, a feature very common to services which persist
> information on behalf of clients which may be sensitive to latency while
> waiting for confirmation of successful persistence.
> Log the client and request details if the server discovers, when finally
> processing the request, that the current time minus arrival time of the
> request is beyond a configured threshold.
> Look at the HBase {{responseTooSlow}} feature for inspiration.
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