wangning has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/15830 )

Change subject: [fs] fixed file num low live ratio metadata compaction policy 
when startup
......................................................................


Patch Set 3:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/15830/2//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/15830/2//COMMIT_MSG@18
PS2, Line 18: nsumption
> nit: consumption
Done


http://gerrit.cloudera.org:8080/#/c/15830/2//COMMIT_MSG@20
PS2, Line 20: ion of live
> nit: remove.
Done


http://gerrit.cloudera.org:8080/#/c/15830/2//COMMIT_MSG@24
PS2, Line 24: during startup.
> Can you explain more about how this flag (which is to limit the number of m
For sure it would be very good to make those files compacted. But it is no 
possible for nodes without sufficient memory to startup. If sometimes it killed 
by OOM killer , it may keeps fail forever without intervention of  Ops.
The metadata files inflate over physical memory is very common to us, I am in 
private deployment company which offer service to other company. The management 
right doesn't belong to us until some module failed. Even if we monitored the 
bad situation of compaction of kudu tserver, it is not possible to restart and 
adjust some parameter without customer's permission.
How the flag could help avoiding OOM during startup is attached in CL.
We some times cut in half of num of metadata files to start once, after some 
compactions and remove the flag and restart it again. With 1.5 times 
expectation of start time but could help the node restart even in not very good 
hardware.


http://gerrit.cloudera.org:8080/#/c/15830/2/src/kudu/fs/log_block_manager.cc
File src/kudu/fs/log_block_manager.cc:

http://gerrit.cloudera.org:8080/#/c/15830/2/src/kudu/fs/log_block_manager.cc@2631
PS2, Line 2631:  FLAGS_max_num_low_live_ratio_metadata_file_to_compact >
              :          l
> nit: alignment.
Done



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ifad1d6de4e61a1ddcfb35743abd71b57d6418896
Gerrit-Change-Number: 15830
Gerrit-PatchSet: 3
Gerrit-Owner: wangning <[email protected]>
Gerrit-Reviewer: Hao Hao <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: wangning <[email protected]>
Gerrit-Comment-Date: Wed, 29 Apr 2020 00:59:26 +0000
Gerrit-HasComments: Yes

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