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spool: fix data race when to exit #42129

Merged
merged 9 commits into from
Mar 13, 2023
Merged

spool: fix data race when to exit #42129

merged 9 commits into from
Mar 13, 2023

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hawkingrei
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@hawkingrei hawkingrei commented Mar 13, 2023 •
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What problem does this PR solve?

Issue Number: close #42130

Problem Summary:

when we are in exit mode, Some tasks still want to start a new goroutine and call waitgroup.Add. but at the same time, we are calling the waitgroup.Wait.
the data race will happen.

What is changed and how it works?

Adding the logic of checking the exit mode when to check the running exit and wait to make all tasks called waitgroup.Add.

Check List

Tests

  • Unit test
  • Integration test
  • Manual test (add detailed scripts or steps below)
  • No code

Side effects

  • Performance regression: Consumes more CPU
  • Performance regression: Consumes more Memory
  • Breaking backward compatibility

Documentation

  • Affects user behaviors
  • Contains syntax changes
  • Contains variable changes
  • Contains experimental features
  • Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

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ti-chi-bot commented Mar 13, 2023 •
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[REVIEW NOTIFICATION]

This pull request has been approved by:

  • GMHDBJD
  • you06

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
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@ti-chi-bot ti-chi-bot added do-not-merge/needs-linked-issue release-note-none Denotes a PR that doesn't merit a release note. size/S Denotes a PR that changes 10-29 lines, ignoring generated files. do-not-merge/needs-triage-completed and removed do-not-merge/needs-linked-issue labels Mar 13, 2023
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/check-issue-triage-complete

@hawkingrei
update
abb7611
@hawkingrei
update
c3e149f 
Signed-off-by: Weizhen Wang <[email protected]>
@hawkingrei hawkingrei requested a review from you06 March 13, 2023 06:39
you06
you06 reviewed Mar 13, 2023
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resourcemanager/pool/spool/spool.go Outdated
@@ -142,7 +145,12 @@ func (p *Pool) RunWithConcurrency(fns chan func(), concurrency uint32) error {

// checkAndAddRunning is to check if a task can run. If can, add the running number.
func (p *Pool) checkAndAddRunning(concurrency uint32) (conc int32, run bool) {
p.waiting.Add(1)
defer p.waiting.Add(-1)
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Move the waiting variable modification into Run? Because it may call p.wg.Add(1) after this checking and the check(for p.waiting.Load() > 0 {...}) in ReleaseAndWait may pass after checkAndAddRunning and before p.wg.Add(1), then there is still possible race.

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You are right.

resourcemanager/pool/spool/spool.go Outdated
@@ -173,6 +181,10 @@ func (p *Pool) checkAndAddRunningInternal(concurrency int32) (conc int32, run bo
// ReleaseAndWait releases the pool and waits for all tasks to be completed.
func (p *Pool) ReleaseAndWait() {
p.isStop.Store(true)
// wait for all the task in the pending to exit
for p.waiting.Load() > 0 {
time.Sleep(waitInterval)
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I want to confirm the usage of ReleaseAndWait. If it may be called in Executor.Close, 5ms sleep is unacceptable. If it's called when TiDB exiting or kvstore closing, this LGTM.

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I remove 5ms sleep first.

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A spinlock is risky because it may loop here while the Run or RunWithConcurrency threads are scheduled out, why not use a condition variable here?

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Done

@hawkingrei
update
3bcc196 
Signed-off-by: Weizhen Wang <[email protected]>
@hawkingrei
update
0183d5c 
Signed-off-by: Weizhen Wang <[email protected]>
@hawkingrei
update
0f0a8af 
Signed-off-by: Weizhen Wang <[email protected]>
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265294d 
Signed-off-by: Weizhen Wang <[email protected]>
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4fbb9ec 
Signed-off-by: Weizhen Wang <[email protected]>
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6277e79 
Signed-off-by: Weizhen Wang <[email protected]>
@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Mar 13, 2023
@hawkingrei hawkingrei requested a review from GMHDBJD March 13, 2023 08:20
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LGTM

@ti-chi-bot ti-chi-bot added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Mar 13, 2023
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/merge

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This pull request has been accepted and is ready to merge.

Commit hash: 6277e79

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Mar 13, 2023
@ti-chi-bot ti-chi-bot merged commit 51c22cd into pingcap:master Mar 13, 2023
@hawkingrei hawkingrei deleted the fix_spool branch March 13, 2023 09:17
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@GMHDBJD GMHDBJD GMHDBJD approved these changes

@you06 you06 you06 approved these changes

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DATA RACE in the TestReleaseWhenRunningPool
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