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https://issues.apache.org/jira/browse/HADOOP-2910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12586998#action_12586998
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Hairong Kuang commented on HADOOP-2910:
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The new patch keeps the old IPC server behavior while throttling the clients
when the call queue is full. Yes, there is a limit on file descriptors. This
patch simply says that it depends on O.S. to decide when to refuse a
connection. Having the accepted connection queue in the server helps if we want
to limit the total number of connections that the server wants to accept.
Setting the backlog queue length is simple, but different operating systems may
its limit on the max length it allows. So it is not portable. And this approach
is not equivalent to the old behavior.
> Throttle IPC Client/Server during bursts of requests or server slowdown
> -----------------------------------------------------------------------
>
> Key: HADOOP-2910
> URL: https://issues.apache.org/jira/browse/HADOOP-2910
> Project: Hadoop Core
> Issue Type: Improvement
> Components: ipc
> Affects Versions: 0.16.0
> Reporter: Hairong Kuang
> Assignee: Hairong Kuang
> Fix For: 0.18.0
>
> Attachments: callQueue.patch, callQueue1.patch, callQueue2.patch,
> callQueue3.patch, throttleClient.patch
>
>
> I propose the following to avoid an IPC server being swarmed by too many
> requests and connections
> 1. Limit call queue length or limit the amount of memory used in the call
> queue. This can be done by including the size of a request in the header and
> storing unmarshaled requests in the call queue.
> 2. If the call queue is full or queue buffer is full, stop reading requests
> from sockets. So requests stay at the server's system buffer or at the client
> side and thus eventually throttle the client.
> 3. Limit the total number of connections. Do not accept new connections if
> the connection limit is exceeded. (Note: this solution is unfair to new
> connections.)
> 4. If receive out of memory exception, close the current connection.
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