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sessionctx: change @@tidb_enable_gogc_tuner default value to 0 #49420
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Codecov Report
Additional details and impacted files@@ Coverage Diff @@
## master #49420 +/- ##
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+ Coverage 71.0551% 80.5023% +9.4471%
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Files 1368 2604 +1236
Lines 401291 762301 +361010
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+ Hits 285138 613670 +328532
- Misses 96328 125088 +28760
- Partials 19825 23543 +3718
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LGTM
[APPROVALNOTIFIER] This PR is NOT APPROVED This pull-request has been approved by: jackysp The full list of commands accepted by this bot can be found here.
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[LGTM Timeline notifier]Timeline:
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I agree with you about this, but could you please provide some real-scenario case that GOGC Tuner leads to stableness issue? IMO it is just designed to provide a 'smart' timeing for GC. |
See what's the attitude from the kernel developers of Go team:
Ref golang/go#48409 We're doing all anti-best practice things |
Is this still being worked on? I think we've encountered a real-world customer issue that the gctuner EDIT: disregard, it is because of the customer manually changing |
What problem does this PR solve?
Issue Number: ref #36503
Problem Summary:
What changed and how does it work?
We prefer stability (jitters, OOM risk, unpredictable latency etc) over performance.
In essential, gogc_tuner is trading stability for performance, it works by reducing Go GC frequency to get better throughput and improve the performance.
Maybe in POC or when the memory usage of the workload is low, we can choose performance first, otherwise it's better to work with the default Go GC settings.
This commit change the default value of @@tidb_enable_gogc_tuner from true to false.
It only affect the new bootstraped cluster, the stored global session variable is not changed,
so upgradation of the old clusters do not affect by this change (they can update this session variable depends on their need).
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