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https://issues.apache.org/jira/browse/ZOOKEEPER-2251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15734535#comment-15734535
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ASF GitHub Bot commented on ZOOKEEPER-2251:
-------------------------------------------
Github user hanm commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/119#discussion_r91666647
--- Diff: src/java/main/org/apache/zookeeper/ClientCnxn.java ---
@@ -1495,10 +1504,21 @@ public ReplyHeader submitRequest(RequestHeader h,
Record request,
Packet packet = queuePacket(h, r, request, response, null, null,
null,
null, watchRegistration, watchDeregistration);
synchronized (packet) {
+ long waitStartTime = System.currentTimeMillis();
while (!packet.finished) {
- packet.wait();
+ packet.wait(requestTimeout);
--- End diff --
This unconditionally adds a timeout is a pretty significant semantic
change. Whether or not we should wait indefinitely is a separate issue to
discuss later, but from a compatibility point of view we'd at least provide a
configuration option to let user opt in this feature rather than having this
turned on by default. So by default there is no timeout and client still waits
indefinitely, user who wants to opt in to turn on the timeout needs to explicit
say so and provide a value they think make sense to them. Otherwise, we'd have
to solve the problem of what the default timeout value we should set in ZK
config if this feature is turned on by default, and that problem is hard and
very likely there is no default value that makes everyone happy.
> Add Client side packet response timeout to avoid infinite wait.
> ---------------------------------------------------------------
>
> Key: ZOOKEEPER-2251
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2251
> Project: ZooKeeper
> Issue Type: Bug
> Components: java client
> Affects Versions: 3.4.9, 3.5.2
> Reporter: nijel
> Assignee: Arshad Mohammad
> Priority: Critical
> Labels: fault
> Fix For: 3.4.10, 3.5.3, 3.6.0
>
> Attachments: ZOOKEEPER-2251-01.patch, ZOOKEEPER-2251-02.patch,
> ZOOKEEPER-2251-03.patch, ZOOKEEPER-2251-04.patch
>
>
> I came across one issue related to Client side packet response timeout In my
> cluster many packet drops happened for some time.
> One observation is the zookeeper client got hanged. As per the thread dump it
> is waiting for the response/ACK for the operation performed (synchronous API
> used here).
> I am using
> zookeeper.serverCnxnFactory=org.apache.zookeeper.server.NIOServerCnxnFactory
> Since only few packets missed there is no DISCONNECTED event occurred.
> Need add a "response time out" for the operations or packets.
> *Comments from [~rakeshr]*
> My observation about the problem:-
> * Can use tools like 'Wireshark' to simulate the artificial packet loss.
> * Assume there is only one packet in the 'outgoingQueue' and unfortunately
> the server response packet lost. Now, client will enter into infinite
> waiting.
> https://github.com/apache/zookeeper/blob/trunk/src/java/main/org/apache/zookeeper/ClientCnxn.java#L1515
> * Probably we can discuss more about this problem and possible solutions(add
> packet ACK timeout or another better approach) in the jira.
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