hadoop-common-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "ZooKeeper/Troubleshooting" by PatrickHunt
Date Wed, 06 May 2009 16:59:36 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The following page has been changed by PatrickHunt:

  ZooKeeper is a canary in a coal mine of sorts. Because of the heart-beating performed by
the clients and servers ZooKeeper based applications are very sensitive to things like network
and system latencies. We often see client disconnects and session expirations associated with
these types of problems.
  Take a look at [http://hadoop.apache.org/zookeeper/docs/current/zookeeperAdmin.html#sc_commonProblems
this section] to start.
+ == Client disconnects due to client side swapping ==
+ [http://hadoop.apache.org/zookeeper/docs/current/zookeeperAdmin.html#sc_commonProblems This
link] specifically discusses the negative impact of swapping in the context of the server.
However this can be an issue for clients as well. Swapping will delay, or potentially even
stop for a significant period, the heartbeats from client to server, resulting in session
+ As told by a user:
+ "This [https://issues.apache.org/jira/browse/ZOOKEEPER-344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12706402#action_12706402
issue] is clearly linked to heavy utilization or swapping on the clients. I find that if I
keep the clients from swapping that this error materializes relatively infrequently, and when
it does materialize it is linked to a sudden increase in load. For example, the concurrent
start of 100 clients on 14 machines will sometimes trigger this issue. <...> All in
all, it is my sense that Java processes must avoid swapping if they want to have not just
timely but also reliable behavior."
  === Hardware misconfiguration - NIC ===

View raw message