ZhangZhen created KUDU-2226:
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Summary: Frequently updated table does not flush DeltaMemStore in
time and will occupy a lot of memory
Key: KUDU-2226
URL: https://issues.apache.org/jira/browse/KUDU-2226
Project: Kudu
Issue Type: Improvement
Affects Versions: 1.3.0
Environment: CentOS6.5 Linux 2.6.32-431
Kudu1.3.0
GitCommit 00813f96b9cb
Reporter: ZhangZhen
I have a table with 10M rows in total and has been hash partitioned to 16
buckets. Each tablet has about 100MB on disk size according to the /tablets Web
UI. Everyday 50K new rows will be inserted into this table, and about 5M rows
of this table will be updated, that's about half of rows in total, each row
will be updated only once.
Then I found something strange, from the /mem-trackers UI of TS, I found every
tablet of this table occupied about 900MB memory, mainly occupied by
DeltaMemStore, the peak memory consumption is about 1.8G.
I don't understand why the DeltaMemStore will cost so much memory, 900MB DMS vs
100MB on disk size, that seems strange to me. What's more, I found these DMS
will be flushed very slowly, so for a long time these memory are occupied,
which cause "Soft memory limit exceeded" in the TS, and in result cause
"Rejecting consensus request".
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