Closed JaySon-Huang closed 1 year ago
When a tiflash instance is hanging (rather than process down), each time when tidb executes a MPP tasks, it takes about 2 sec to detect whether the tiflash instance is alive or not. And Apply_26
will cause serval MPP tasks and takes too much time in detecting tiflash alive.
/cc @windtalker
Workaround: set tidb_allow_mpp = 0
to bypass the tiflash instance alive detecting.
/label sig/execution
@JaySon-Huang: The label(s) sig/execution
cannot be applied. These labels are supported: fuzz/sqlancer, challenge-program, compatibility-breaker, first-time-contributor, contribution, require-LGT3, good first issue, correctness, duplicate, proposal, security, needs-more-info, needs-cherry-pick-release-4.0, needs-cherry-pick-release-5.0, needs-cherry-pick-release-5.1, needs-cherry-pick-release-5.2, needs-cherry-pick-release-5.3, needs-cherry-pick-release-5.4, needs-cherry-pick-release-6.0, needs-cherry-pick-release-6.1, needs-cherry-pick-release-6.2, needs-cherry-pick-release-6.3, needs-cherry-pick-release-6.4, needs-cherry-pick-release-6.5, affects-4.0, affects-5.0, affects-5.1, affects-5.2, affects-5.3, affects-5.4, affects-6.0, affects-6.1, affects-6.2, affects-6.3, affects-6.4, affects-6.5, may-affects-4.0, may-affects-5.0, may-affects-5.1, may-affects-5.2, may-affects-5.3, may-affects-5.4, may-affects-6.0, may-affects-6.1, may-affects-6.2, may-affects-6.3, may-affects-6.4, may-affects-6.5
.
Required by customer and need to be fixed in 6.1.x
This requires a decent reimplementation of current aliveness mechanism. Will be done as an big improvement in the future.
Bug Report
Please answer these questions before submitting your issue. Thanks!
1. Minimal reproduce step (Required)
2. What did you expect to see? (Required)
When all tiflash instances are normal, the response time is about 7.5 sec in my env. After 1 tiflash instance hang, the response time of executing query 41 may slightly degrade to 8 sec or so
3. What did you see instead (Required)
After 1 tiflash instance hang, the response time increase from about 7.5 sec to more than 133 sec
tpc-ds query 41
4. What is your TiDB version? (Required)
6.5.0