cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-220) TCP writes get stuck
Date Sat, 13 Jun 2009 00:33:07 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12719048#action_12719048
] 

Jonathan Ellis commented on CASSANDRA-220:
------------------------------------------

I know nio is sexier, but maybe it would be better to rip it out and just go with thread-per-socket.

http://java.dzone.com/articles/avoid-nio-get-better-throughpu (read the linked slides)

> TCP writes get stuck
> --------------------
>
>                 Key: CASSANDRA-220
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-220
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: trunk
>            Reporter: Jun Rao
>            Assignee: Jun Rao
>             Fix For: trunk
>
>         Attachments: 220-2.patch, 220-3.patch, issue220.patchv1
>
>
> In our test cluster, I observed that on some nodes, TCP writes get accumulated in TcpConnection.pendingWrites.
However, the selector never gets a ready to write event. As a result, all writes get stuck.
This is because write(message) and doPendingWrites() are not fully synchronized.  This following
situation can happen:
> 1. write(message) adds stuff to pendingWrites.
> 2. a ready to write event happens; in doPendingWrites() buffered requests are written
to socket
> 3. another write request happens, in write(message), the test for pendingWrites.isEmpty()
is false
> 4. doPendingWrites() finishes writing all buffered request to socket
> 5. in write(message), the new request is added to pendingWrites
> Now, ready to write events will never happen again and all write requests get stuck in
pendingWrites.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message