Feifan Wang created FLINK-21986:
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Summary: taskmanager native memory not release timely after restart
Key: FLINK-21986
URL: https://issues.apache.org/jira/browse/FLINK-21986
Project: Flink
Issue Type: Bug
Components: Runtime / State Backends
Affects Versions: 1.12.1
Environment: flink version：1.12.1
run ：yarn session
job type：mock source -> regular join
checkpoint interval: 3m
Taskmanager memory : 16G
Reporter: Feifan Wang
Attachments: image-2021-03-25-15-53-44-214.png,
image-2021-03-25-16-07-29-083.png, image-2021-03-26-11-46-06-828.png,
image-2021-03-26-11-47-21-388.png
I run a regular join job with flink_1.12.1 , and find taskmanager native memory
not release timely after restart cause by exceeded checkpoint tolerable failure
threshold.
*problem job information：*
# job first restart cause by exceeded checkpoint tolerable failure threshold.
# then taskmanager be killed by yarn many times
# in this case，tm heap is set to 7.68G，bug all tm heap size is under 4.2G
!image-2021-03-25-15-53-44-214.png|width=496,height=103!
# nonheap size increase after restart，but still under 160M.
!https://km.sankuai.com/api/file/cdn/706284607/716474606?contentType=1&isNewContent=false&isNewContent=false|width=493,height=102!
# taskmanager process memory increase 3-4G after restart（this figure show one
of taskmanager）
!image-2021-03-25-16-07-29-083.png|width=493,height=107!
*my guess：*
[RocksDB
wiki|https://github.com/facebook/rocksdb/wiki/RocksJava-Basics#memory-management]
mentioned ：Many of the Java Objects used in the RocksJava API will be backed
by C++ objects for which the Java Objects have ownership. As C++ has no notion
of automatic garbage collection for its heap in the way that Java does, we must
explicitly free the memory used by the C++ objects when we are finished with
them.
So, is it possible that RocksDBStateBackend not call
AbstractNativeReference#close() to release memory use by RocksDB C++ Object ?
*I make a change:*
Actively call System.gc() and System.runFinalization() every minute.
*And run this test again:*
# taskmanager process memory no obvious increase
!image-2021-03-26-11-46-06-828.png|width=495,height=93!
# job run for several days，and restart many times，but no taskmanager killed by
yarn like before
*Summary：*
# first，there is some native memory can not release timely after restart in
this situation
# I guess it maybe RocksDB C++ object，but I hive not check it from source code
of RocksDBStateBackend
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