pingcap / pingcap/tiflash

TiFlash response time is not stable

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Dominant language
C++
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Description

Under sysbench workload.

Normally, the query time of select count(*) from sbtest1; is about 0.2s.
However, the query time becomes about 2~3.xs occasionally.
https://github.com/pingcap/tics/issues/1230#issuecomment-731915154

TiFlash version: release-4.0 branch, https://github.com/pingcap/tics/commit/ba6c560921c42f37657ddba65d5b57bd75dffe96

sysbench command:

sysbench --config-file=jayson_85_disk_sysbench_config.txt oltp_update_index --tables=1 --table-size=10000000  --threads=100 run

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Research direction

Reproduce the issue on the release-4.0 TiFlash commit ba6c560921c42f37657ddba65d5b57bd75dffe96 using the stated sysbench command and jayson_85_disk_sysbench_config.txt. Compare repeated timings for select count(*) from sbtest1; under the workload; done means identifying and fixing the cause of the occasional 2–3.x-second responses, with stable results demonstrated.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
databases
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

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