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https://issues.apache.org/jira/browse/FLINK-4094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15409276#comment-15409276
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ASF GitHub Bot commented on FLINK-4094:
---------------------------------------
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/2336#discussion_r73670793
--- Diff: docs/setup/config.md ---
@@ -83,7 +83,8 @@ The default fraction for managed memory can be adjusted
using the `taskmanager.m
- `taskmanager.memory.segment-size`: The size of memory buffers used by
the memory manager and the network stack in bytes (DEFAULT: 32768 (= 32
KiBytes)).
-- `taskmanager.memory.preallocate`: Can be either of `true` or `false`.
Specifies whether task managers should allocate all managed memory when
starting up. (DEFAULT: false)
+- `taskmanager.memory.preallocate`: Can be either of `true` or `false`.
Specifies whether task managers should allocate all managed memory when
starting up. (DEFAULT: false). When `taskmanager.memory.off-heap` is set to
`true`, then it is advised that this configuration is also set to `true`,
because when set to
+`false`, cleaning up of the allocated offheap memory kicks up only when
the configured JVM parameter MaxDirectMemorySize is reached by triggering a
full GC.
--- End diff --
"kicks up" --> "happens".
The reading flow is easier if this is split into two sentences (I would
split at ", because")
> Off heap memory deallocation might not properly work
> ----------------------------------------------------
>
> Key: FLINK-4094
> URL: https://issues.apache.org/jira/browse/FLINK-4094
> Project: Flink
> Issue Type: Bug
> Components: Local Runtime
> Affects Versions: 1.1.0
> Reporter: Till Rohrmann
> Assignee: ramkrishna.s.vasudevan
> Priority: Critical
>
> A user reported that off-heap memory is not properly deallocated when setting
> {{taskmanager.memory.preallocate:false}} (per default) [1]. This can cause
> the TaskManager process being killed by the OS.
> It should be possible to execute multiple batch jobs with preallocation
> turned off. No longer used direct memory buffers should be properly garbage
> collected so that the JVM process does not exceed it's maximum memory bounds.
> [1]
> http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/offheap-memory-allocation-and-memory-leak-bug-td12154.html
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