localbackend: fix resource leak when err on new local backend

[D3Hunter]

What problem does this PR solve?

Issue Number: close #53659

Problem Summary:

What changed and how does it work?

• close them on error

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

i think it's too much to add so many failpoints to just test resource closed on err, so i write the test here

apply this diff to the code

diff --git a/pkg/lightning/backend/local/local.go b/pkg/lightning/backend/local/local.go
index f232d71d79..1d91833fa8 100644
--- a/pkg/lightning/backend/local/local.go
+++ b/pkg/lightning/backend/local/local.go
@@ -560,12 +560,14 @@ func NewBackend(
 		// the interface `ScatterRegions` may time out.
 		pd.WithCustomTimeoutOption(60*time.Second),
 	)
+	failpoint.InjectCall("failedToCreatePDClient", &err)
 	if err != nil {
 		return nil, common.NormalizeOrWrapErr(common.ErrCreatePDClient, err)
 	}
 
 	// The following copies tikv.NewTxnClient without creating yet another pdClient.
 	spkv, err = tikvclient.NewEtcdSafePointKV(strings.Split(config.PDAddr, ","), tls.TLSConfig())
+	failpoint.InjectCall("failedToCreateSafePointKV", &err)
 	if err != nil {
 		return nil, common.ErrCreateKVClient.Wrap(err).GenWithStackByArgs()
 	}
@@ -582,6 +584,7 @@ func NewBackend(
 	tikvCodec := pdCliForTiKV.GetCodec()
 	rpcCli = tikvclient.NewRPCClient(tikvclient.WithSecurity(tls.ToTiKVSecurityConfig()), tikvclient.WithCodec(tikvCodec))
 	tikvCli, err = tikvclient.NewKVStore("lightning-local-backend", pdCliForTiKV, spkv, rpcCli)
+	failpoint.InjectCall("failedToCreateKVStore", &err)
 	if err != nil {
 		return nil, common.ErrCreateKVClient.Wrap(err).GenWithStackByArgs()
 	}
@@ -594,6 +597,7 @@ func NewBackend(
 	importClientFactory = newImportClientFactoryImpl(splitCli, tls, config.MaxConnPerStore, config.ConnCompressType)
 
 	multiIngestSupported, err = checkMultiIngestSupport(ctx, pdCli, importClientFactory)
+	failpoint.InjectCall("failedToCheckMultiIngestSupport", &err)
 	if err != nil {
 		return nil, common.ErrCheckMultiIngest.Wrap(err).GenWithStackByArgs()
 	}

then in real-tikv-test which have routine leak check, add this:

func TestLocalBackendCleanOnErr(t *testing.T) {
	for _, fp := range []string{
		"failedToCreatePDClient",
		"failedToCreateSafePointKV",
		"failedToCreateKVStore",
		"failedToCheckMultiIngestSupport",
	} {
		t.Run(fp, func(t *testing.T) {
			fpName := "github.com/pingcap/tidb/pkg/lightning/backend/local/" + fp
			testfailpoint.EnableCall(t, fpName,
				func(errP *error) {
					*errP = fmt.Errorf("mock error" + fp)
				},
			)
			t.Cleanup(func() {
				require.NoError(t, failpoint.Disable(fpName))
			})
			_, err := local.NewBackend(context.Background(), &common.TLS{}, local.BackendConfig{
				PDAddr:                 "127.0.0.1:2379",
				RegionSplitBatchSize:   10,
				RegionSplitConcurrency: 1,
				MaxConnPerStore:        1,
				ConnCompressType:       config.CompressionNone,
			}, nil)
			require.ErrorContains(t, err, "mock error"+fp)
		})
	}
}

• 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]

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[D3Hunter]

make sure we can see context cancel as a error, not a string

[codecov]

Codecov Report

Attention: Patch coverage is 76.19048% with 15 lines in your changes are missing coverage. Please review.

Project coverage is 75.0389%. Comparing base (2b68ccf) to head (61bfa6a).
Report is 5 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #53664        +/-   ##
================================================
+ Coverage   74.4613%   75.0389%   +0.5775%     
================================================
  Files          1506       1528        +22     
  Lines        357521     439893     +82372     
================================================
+ Hits         266215     330091     +63876     
- Misses        71899      89150     +17251     
- Partials      19407      20652      +1245     

Flag	Coverage Δ
integration	51.4650% <71.4285%> (?)
unit	71.4981% <17.4603%> (-1.8443%)	⬇️

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

Components	Coverage Δ
dumpling	53.9957% <ø> (-2.3014%)	⬇️
parser	∅ <ø> (∅)
br	56.7480% <100.0000%> (+13.1993%)	⬆️

[GMHDBJD]

LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-05-30 02:25:09.60171102 +0000 UTC m=+2916063.358846592: ☑️ agreed by lance6716.
• 2024-05-30 03:17:54.340401591 +0000 UTC m=+2919228.097537157: ☑️ agreed by GMHDBJD.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: GMHDBJD, lance6716, Leavrth

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Needs approval from an approver in each of these files:

• br/OWNERS [Leavrth]
• pkg/lightning/OWNERS [GMHDBJD,lance6716]

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[GMHDBJD]

/run-cherry-pick

[GMHDBJD]

/run-cherrypick

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #54618.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #55066.