[jira] Issue Comment Edited: (HADOOP-2910) Throttle IPC Client/Server during bursts of requests or server slowdown

["Raghu Angadi (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-2910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12580154#action_12580154 ] 

rangadi edited comment on HADOOP-2910 at 3/18/08 3:45 PM:
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Note that removing connect timeout does not mean connect will wait as long as server is up. It just makes the timeout to whatever TCP has (around 5 min?). So if the server is very busy and does not accept (i.e. ignores syns), client will still fail (which I think is not that bad).

One thing I am not sure is if there is a possibility where connect() will hang forever.. which would be strange to the user.. there is no equivalent of ping as in HADOOP-2188.

Edit : typos.

      was (Author: rangadi):
    
Note that removing connect does not mean connect will wait as long as server is up. It just makes the timeout to whatever TCP has (around 5 min?). So if the client is very busy and does not accept (i.e. ignores syns), client will still fail (which I think is not that bad).

One thing I am not sure is if there is a possibility where connect() will hang forever.. which would be strange to the user.. there is no equivalent of ping as in HADOOP-2188.
  
> 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: 0.17.0
>
>         Attachments: callQueue.patch, callQueue1.patch, callQueue2.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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