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https://issues.apache.org/jira/browse/HADOOP-1849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12832777#action_12832777
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Hong Tang commented on HADOOP-1849:
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bq. Server keeps reading RPC requests from clients. When the number in-flight
RPCs is larger than maxQsize, the earliest RPCs are deleted. This is the main
feedback Server has for the client. I have often heard from users that Hadoop
doesn't handle bursty traffic.
This means the server still wastes resources on retrieving bytes and
constructing objects for the dropped request. Also, do we perform a check right
before the rpc handler process the request whether the client already abandoned
the request?
> IPC server max queue size should be configurable
> ------------------------------------------------
>
> Key: HADOOP-1849
> URL: https://issues.apache.org/jira/browse/HADOOP-1849
> Project: Hadoop Common
> Issue Type: Improvement
> Components: ipc
> Reporter: Raghu Angadi
> Assignee: Konstantin Shvachko
>
> Currently max queue size for IPC server is set to (100 * handlers). Usually
> when RPC failures are observed (e.g. HADOOP-1763), we increase number of
> handlers and the problem goes away. I think a big part of such a fix is
> increase in max queue size. I think we should make maxQsize per handler
> configurable (with a bigger default than 100). There are other improvements
> also (HADOOP-1841).
> Server keeps reading RPC requests from clients. When the number in-flight
> RPCs is larger than maxQsize, the earliest RPCs are deleted. This is the main
> feedback Server has for the client. I have often heard from users that Hadoop
> doesn't handle bursty traffic.
> Say handler count is 10 (default) and Server can handle 1000 RPCs a sec
> (quite conservative/low for a typical server), it implies that an RPC can
> wait for only for 1 sec before it is dropped. If there 3000 clients and all
> of them send RPCs around the same time (not very rare, with heartbeats etc),
> 2000 will be dropped. In stead of dropping the earliest RPCs, if the server
> delays reading new RPCs, the feedback to clients would be much smoother, I
> will file another jira regd queue management.
> For this jira I propose to make queue size per handler configurable, with a
> larger default (may be 500).
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