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txn: fix the ttlmanager and cleanup logic for 1pc and async commit #23342

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merged 7 commits into from
Mar 18, 2021

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cfzjywxk
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@cfzjywxk cfzjywxk commented Mar 16, 2021

What problem does this PR solve?

Issue Number: close #23331

Problem Summary:
There are two problems:

  • The left pessimistic locks are not cleaned up using 1pc protocol to commit, blocking other concurrent transactions on these keys.
  • The ttlManager is not closed, if the max ts caculation error is reported using async commit or 1pc, thus the left pessimistic locks could not be resolved by the ddl backfill worker.

What is changed and how it works?

What's Changed:

  1. Do cleanup if the error is reported when 1pc protocol is used.
  2. Close the ttlManager if the execution result of twoPhaseCommitter is error.

How it Works:

Related changes

  • Need to cherry-pick to the release branch

Check List

Tests

  • Unit test

Side effects

Release note

  • No release note.

@cfzjywxk cfzjywxk added type/bugfix This PR fixes a bug. sig/transaction SIG:Transaction labels Mar 16, 2021
@ti-chi-bot ti-chi-bot added the size/M Denotes a PR that changes 30-99 lines, ignoring generated files. label Mar 16, 2021
@cfzjywxk cfzjywxk requested a review from zyguan March 16, 2021 07:24
@@ -920,6 +920,9 @@ func (c *twoPhaseCommitter) execute(ctx context.Context) (err error) {
if c.isOnePC() {
// The error means the 1PC transaction failed.
if err != nil {
if c.getUndeterminedErr() == nil {
c.cleanup(ctx)
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Should we just use something like pessimisticRollbackMutations if it's pessimistic transactions instead of cleanup.

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I think there won't be too much difference, but maybe we can skip this for optimistic 1pc transactions. @sticnarf How do you think?

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@sticnarf sticnarf Mar 16, 2021

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We can always use pessimistic rollback because an optimistic one pc won't leave any waste.

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How about changing cleanup()?

		cleanupKeysCtx := context.WithValue(context.Background(), TxnStartKey, ctx.Value(TxnStartKey))
		var err error
		if c.isPessimistic && c.isOnePC() {
			err = c.pessimisticRollbackMutations(NewBackofferWithVars(cleanupKeysCtx, cleanupMaxBackoff, c.txn.vars), c.mutations)
		} else {
			err = c.cleanupMutations(NewBackofferWithVars(cleanupKeysCtx, cleanupMaxBackoff, c.txn.vars), c.mutations)

		}
		if err != nil {

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@youjiali1995 We needn't do cleanup for optimistic 1PC, so I suggest this:

if !c.isOnePC() {
	err = c.cleanupMutations(NewBackofferWithVars(cleanupKeysCtx, cleanupMaxBackoff, c.txn.vars), c.mutations)
} else if c.isPessimistic {
	err = c.pessimisticRollbackMutations(NewBackofferWithVars(cleanupKeysCtx, cleanupMaxBackoff, c.txn.vars), c.mutations)
}

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My mistake.

@github-actions github-actions bot added the sig/sql-infra SIG: SQL Infra label Mar 16, 2021
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LGTM

@@ -920,6 +920,9 @@ func (c *twoPhaseCommitter) execute(ctx context.Context) (err error) {
if c.isOnePC() {
// The error means the 1PC transaction failed.
if err != nil {
if c.getUndeterminedErr() == nil {
c.cleanup(ctx)
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I think there won't be too much difference, but maybe we can skip this for optimistic 1pc transactions. @sticnarf How do you think?

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@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Mar 16, 2021
@ichn-hu ichn-hu mentioned this pull request Mar 16, 2021
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@sticnarf @youjiali1995 PTAL

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Rest LGTM

@@ -250,7 +250,11 @@ func (txn *KVTxn) Commit(ctx context.Context) error {
}
defer func() {
// For async commit transactions, the ttl manager will be closed in the asynchronous commit goroutine.
if !committer.isAsyncCommit() {
if committer.isAsyncCommit() || committer.isOnePC() {
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@sticnarf @youjiali1995

Could we just always close the ttl manager here, seems at commit phase and the async commit/1pc transaction size will be small.

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I think it is okay. The chance is small that TTL expires before the primary lock is committed.

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I think yes because SafeWindow(2s) is smaller than the interval of keepAlive(10s). It's nearly useless here.

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It seems to me not related to SafeWindow. SafeWindow only constrains the prewrite time.

@@ -899,15 +899,20 @@ func (c *twoPhaseCommitter) cleanup(ctx context.Context) {
})

cleanupKeysCtx := context.WithValue(context.Background(), TxnStartKey, ctx.Value(TxnStartKey))
err := c.cleanupMutations(NewBackofferWithVars(cleanupKeysCtx, cleanupMaxBackoff, c.txn.vars), c.mutations)
var err error
if c.isPessimistic && c.isOnePC() {
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How about skipping cleanup for optimistic one pc? https://github.com/pingcap/tidb/pull/23342/files#r596528085

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@sticnarf
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Should also remove https://github.com/pingcap/tidb/pull/23342/files#diff-7352f99d1adcf12eded39ff8934684296725268e9116dcecfa16f560827f9271R1173

I cannot see the line you refer to. I guess it's the defer c.ttlManager.close() in the asynchrounous commit stage?

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I cannot see the line you refer to. I guess it's the defer c.ttlManager.close() in the asynchrounous commit stage?

Yes.

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Should also remove https://github.com/pingcap/tidb/pull/23342/files#diff-7352f99d1adcf12eded39ff8934684296725268e9116dcecfa16f560827f9271R1173

I cannot see the line you refer to. I guess it's the defer c.ttlManager.close() in the asynchrounous commit stage?

Got, it's removed.

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[REVIEW NOTIFICATION]

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  • MyonKeminta
  • youjiali1995

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@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 18, 2021
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Lgtm

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/merge

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

Commit hash: 76838b2

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Mar 18, 2021
@ti-chi-bot ti-chi-bot merged commit 1ab3b48 into pingcap:master Mar 18, 2021
ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 18, 2021
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cherry pick to release-5.0 in PR #23388

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The ddl test suite of stmtflow failed with 1pc enabled
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