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https://issues.apache.org/jira/browse/HDFS-5788?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13873839#comment-13873839
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Jason Lowe commented on HDFS-5788:
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They are usually short-lived but a bit longer-lived when we can't push them out
the network in a timely manner. Then due to lack of flow control in the RPC
layer we can fill up the heap with these given a large enough average response
buffer per call and enough clients. See HADOOP-8942.
This change mitigates the issue for listLocatedStatus since a much smaller
response payload means it takes a lot more simultaneous clients to consume an
equal amount of heap space.
> listLocatedStatus response can be very large
> --------------------------------------------
>
> Key: HDFS-5788
> URL: https://issues.apache.org/jira/browse/HDFS-5788
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 3.0.0, 0.23.10, 2.2.0
> Reporter: Nathan Roberts
> Assignee: Nathan Roberts
>
> Currently we limit the size of listStatus requests to a default of 1000
> entries. This works fine except in the case of listLocatedStatus where the
> location information can be quite large. As an example, a directory with 7000
> entries, 4 blocks each, 3 way replication - a listLocatedStatus response is
> over 1MB. This can chew up very large amounts of memory in the NN if lots of
> clients try to do this simultaneously.
> Seems like it would be better if we also considered the amount of location
> information being returned when deciding how many files to return.
> Patch will follow shortly.
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