Fix a potential goroutine leak #114071

Mskxn · 2022-11-22T14:39:04Z

What type of PR is this?

/kind bug

What this PR does / why we need it:

When the server stopped before timeout, the stopped <-true will be executed and in the select block, the first case will be chosen. This will lead to a hanging goroutine at line 111 because no receiver of timeout is left. Changing the timeout chan to a buffered one can fix it.

Which issue(s) this PR fixes:

Fixes #114070

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

k8s-ci-robot · 2022-11-22T14:39:09Z

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k8s-ci-robot · 2022-11-22T14:39:14Z

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k8s-ci-robot · 2022-11-22T14:39:14Z

Hi @Mskxn. Thanks for your PR.

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k8s-triage-robot · 2022-11-22T16:43:04Z

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linux-foundation-easycla · 2022-11-22T16:43:08Z

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✅ login: Mskxn (5f94aa3ea45518e8f9a907fd01be9cd217b4e789)

aojea · 2022-11-22T18:23:09Z

can you add a test demonstrating the problem?

Mskxn · 2022-11-23T15:36:48Z

Actually, it is very similar to #102637. I think TestMigrate in integration_test.go can trigger it with a leak checker like goleak which can detect partial goroutine leak

fedebongio · 2022-11-29T21:17:48Z

/assign @aojea
/triage accepted

aojea · 2022-11-29T23:35:51Z

/ok-to-test
/lgmt
/approve

Thanks

aojea · 2022-11-29T23:36:00Z

/lgtm

aojea · 2022-11-29T23:36:57Z

Actually, it is very similar to #102637. I think TestMigrate in integration_test.go can trigger it with a leak checker like goleak which can detect partial goroutine leak

yep, thanks for the clarification, I should have paid more attention

wojtek-t · 2022-11-30T14:36:17Z

cluster/images/etcd/migrate/migrate_server.go

@@ -105,7 +105,7 @@ func (r *EtcdMigrateServer) Stop() error {
 	}
 	gracefulWait := time.Minute * 2
 	stopped := make(chan bool)
-	timedout := make(chan bool)
+	timedout := make(chan bool, 1)


Instead of that, instead of sending an item to a channel, we should simply close it.

wojtek-t · 2022-11-30T14:36:28Z

/hold

wojtek-t · 2022-11-30T15:19:32Z

cluster/images/etcd/migrate/migrate_server.go

@@ -108,7 +108,7 @@ func (r *EtcdMigrateServer) Stop() error {
 	timedout := make(chan bool)
 	go func() {
 		time.Sleep(gracefulWait)
-		timedout <- true
+		close(timedout)


Given you're touching it, can you please also fix line 72:
https://github.com/kubernetes/kubernetes/blob/96360055842db86ff883993824a9b9bd0563b58e/cluster/images/etcd/migrate/migrate_server.go#L72

?

wojtek-t · 2022-11-30T15:37:58Z

@Mskxn - please squash commits, one squashed, this LGTM

Close the channel instead of write to it to avoid hanging goroutine.

Mskxn · 2022-11-30T17:16:35Z

squashed and PTAL.

wojtek-t · 2022-12-01T09:05:42Z

/lgtm
/approve

/hold cancel

/milestone v1.27

k8s-ci-robot · 2022-12-01T09:05:50Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aojea, Mskxn, wojtek-t

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

~~cluster/images/etcd/OWNERS~~ [wojtek-t]

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dims · 2022-12-10T12:46:17Z

/retest

k8s-ci-robot added kind/bug Categorizes issue or PR as related to a bug. size/XS Denotes a PR that changes 0-9 lines, ignoring generated files. do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. labels Nov 22, 2022

k8s-ci-robot requested a review from jpbetz November 22, 2022 14:39

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Mskxn mentioned this pull request Nov 22, 2022

Goroutine leak in EtcdMigrateServer #114070

Closed

k8s-ci-robot added cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. and removed cncf-cla: no Indicates the PR's author has not signed the CNCF CLA. labels Nov 22, 2022

k8s-ci-robot assigned aojea Nov 29, 2022

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wojtek-t reviewed Nov 30, 2022

View reviewed changes

k8s-ci-robot added the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Nov 30, 2022

wojtek-t self-assigned this Nov 30, 2022

k8s-ci-robot removed the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Nov 30, 2022

wojtek-t reviewed Nov 30, 2022

View reviewed changes

Fix go routine leaks

1444f08

Close the channel instead of write to it to avoid hanging goroutine.

k8s-ci-robot removed the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Dec 1, 2022

k8s-ci-robot added this to the v1.27 milestone Dec 1, 2022

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k8s-ci-robot merged commit 89f6cb3 into kubernetes:master Dec 10, 2022

k8s-ci-robot modified the milestones: v1.27, v1.26 Dec 10, 2022

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Fix a potential goroutine leak #114071

Fix a potential goroutine leak #114071

Mskxn commented Nov 22, 2022 •

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dims commented Dec 10, 2022

Fix a potential goroutine leak #114071

Fix a potential goroutine leak #114071

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Mskxn commented Nov 22, 2022 • edited Loading

What type of PR is this?

What this PR does / why we need it:

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

k8s-ci-robot commented Nov 22, 2022

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