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https://issues.apache.org/jira/browse/ZOOKEEPER-2770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16213978#comment-16213978
]
ASF GitHub Bot commented on ZOOKEEPER-2770:
-------------------------------------------
Github user eribeiro commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/307#discussion_r146108343
--- Diff: src/java/main/org/apache/zookeeper/server/ServerStats.java ---
@@ -21,17 +21,32 @@
import org.apache.zookeeper.common.Time;
+import org.apache.zookeeper.server.quorum.QuorumPeerConfig;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Timer;
+import java.util.TimerTask;
/**
* Basic Server Statistics
*/
public class ServerStats {
+ private static final Logger LOG =
LoggerFactory.getLogger(ServerStats.class);
+
private long packetsSent;
private long packetsReceived;
private long maxLatency;
private long minLatency = Long.MAX_VALUE;
private long totalLatency = 0;
private long count = 0;
+ private long numRequestsAboveThresholdTime = 0;
+
+ final static long requestWarnThresholdMs =
QuorumPeerConfig.getRequestWarnResponseThresholdMs();
+ final static Timer timer = new Timer();
+ volatile Boolean waitForLoggingWarnThresholdMsg = false;
--- End diff --
Oh, excuse me, I got it. It's because you are synchronizing on it, right?
Well, it's not recommended (anti-pattern) to synchronize on non-final fields.
Didn't Findbugs raised a warning about this?
> 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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