disttask: correct the usage of context

[tangenta]

What problem does this PR solve?

Issue Number: close #48303

Problem Summary:

After cancelling the job, I found that the ingest worker did not stop. Instead, it was waiting for the server side(TiKV):

11 @ 0x1c2d6ee 0x1c3e185 0x21cf23c 0x225699a 0x2256987 0x2255c1f 0x22548da 0x2255a73 0x3d9bb96 0x3d999f1 0x3d98066 0x3d8942b 0x3d88f47 0x3d8be0e 0x3ac2a96 0x1c625c1
#	0x21cf23b	google.golang.org/grpc/internal/transport.(*Stream).waitOnHeader+0x7b			/go/pkg/mod/google.golang.org/[email protected]/internal/transport/transport.go:327
#	0x2256999	google.golang.org/grpc/internal/transport.(*Stream).RecvCompress+0xb9			/go/pkg/mod/google.golang.org/[email protected]/internal/transport/transport.go:342
#	0x2256986	google.golang.org/grpc.(*csAttempt).recvMsg+0xa6					/go/pkg/mod/google.golang.org/[email protected]/stream.go:1070
#	0x2255c1e	google.golang.org/grpc.(*clientStream).RecvMsg.func1+0x1e				/go/pkg/mod/google.golang.org/[email protected]/stream.go:927
#	0x22548d9	google.golang.org/grpc.(*clientStream).withRetry+0x139					/go/pkg/mod/google.golang.org/[email protected]/stream.go:776
#	0x2255a72	google.golang.org/grpc.(*clientStream).RecvMsg+0x112					/go/pkg/mod/google.golang.org/[email protected]/stream.go:926
#	0x3d9bb95	github.com/pingcap/tidb/br/pkg/lightning/backend/local.(*Backend).doWrite.func5+0x2b5	/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/br/pkg/lightning/backend/local/region_job.go:354
#	0x3d999f0	github.com/pingcap/tidb/br/pkg/lightning/backend/local.(*Backend).doWrite+0x1890	/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/br/pkg/lightning/backend/local/region_job.go:389
#	0x3d98065	github.com/pingcap/tidb/br/pkg/lightning/backend/local.(*Backend).writeToTiKV+0x25	/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/br/pkg/lightning/backend/local/region_job.go:189
#	0x3d8942a	github.com/pingcap/tidb/br/pkg/lightning/backend/local.(*Backend).executeJob+0xaa	/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/br/pkg/lightning/backend/local/local.go:1435
#	0x3d88f46	github.com/pingcap/tidb/br/pkg/lightning/backend/local.(*Backend).startWorker+0x1c6	/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/br/pkg/lightning/backend/local/local.go:1344
#	0x3d8be0d	github.com/pingcap/tidb/br/pkg/lightning/backend/local.(*Backend).doImport.func5+0x2d	/home/jenkins/agent/workspace/build-common/go/src/github.com/pingcap/tidb/br/pkg/lightning/backend/local/local.go:1677
#	0x3ac2a95	golang.org/x/sync/errgroup.(*Group).Go.func1+0x55

Normally, it should quit when the related context is canceled.

func (s *Stream) waitOnHeader() {
	if s.headerChan == nil {
		// On the server headerChan is always nil since a stream originates
		// only after having received headers.
		return
	}
	select {
	case <-s.ctx.Done():
		// Close the stream to prevent headers/trailers from changing after
		// this function returns.
		s.ct.CloseStream(s, ContextErr(s.ctx.Err()))
		// headerChan could possibly not be closed yet if closeStream raced
		// with operateHeaders; wait until it is closed explicitly here.
		<-s.headerChan
	case <-s.headerChan:
	}
}

Finally I found that the context passed to the local backend is wrong. It should be "task context" instead of "manager context", because the latter will only be canceled when the TiDB process exits.

As for the problem of getting stuck, there should be other solutions: #48352.

What is changed and how it works?

• For scheduler methods such as Init(), Run(), Pause(), etc., we pass the task context.
• For interactions with the task table, we pass the manager context.

Check List

Tests

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

  • I checked and no code files have been changed.

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

[tiprow]

Hi @tangenta. Thanks for your PR.

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[codecov]

Codecov Report

Merging #48343 (044dfab) into master (662528d) will increase coverage by 1.4455%.
Report is 4 commits behind head on master.
The diff coverage is 93.3333%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #48343        +/-   ##
================================================
+ Coverage   71.3789%   72.8244%   +1.4455%     
================================================
  Files          1402       1425        +23     
  Lines        406735     413129      +6394     
================================================
+ Hits         290323     300859     +10536     
+ Misses        96491      93354      -3137     
+ Partials      19921      18916      -1005     

Flag	Coverage Δ
integration	43.4756% <0.0000%> (?)
unit	71.3974% <93.3333%> (+0.0185%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9874% <ø> (ø)
parser	∅ <ø> (∅)
br	48.6843% <ø> (-4.2287%)	⬇️

[ywqzzy]

/retest

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[tangenta]

/ok-to-test

[ywqzzy]

/retest

[ywqzzy]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: wjhuang2016, ywqzzy

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Needs approval from an approver in each of these files:

• OWNERS [wjhuang2016]
• pkg/disttask/OWNERS [wjhuang2016,ywqzzy]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-11-07 10:20:22.132579172 +0000 UTC m=+3553219.719689301: ☑️ agreed by ywqzzy.
• 2023-11-07 10:27:35.753494134 +0000 UTC m=+3553653.340604278: ☑️ agreed by wjhuang2016.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #48369.