[Filebeat] Fix reference leak in TCP and Unix socket inputs by andrewkroh · Pull Request #19459 · elastic/beats

andrewkroh · 2020-06-26T14:17:00Z

What does this PR do?

The tcp and unix input sources were leaking references causing a memory leak.
When an accepted connection ended inputsource/common.Closer was
supposed to delete the pointer that it held to the connection, but due to a code
error delete was being called on the wrong map.

Why is it important?

This fixes a memory leak with the tcp and unix inputs.

Checklist

My code follows the style guidelines of this project
I have commented my code, particularly in hard-to-understand areas
I have made corresponding changes to the documentation
I have made corresponding change to the default configuration files
I have added tests that prove my fix is effective or that my feature works
I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

elasticmachine · 2020-06-26T14:17:38Z

Pinging @elastic/integrations-services (Team:Services)

urso · 2020-06-26T15:52:26Z

Good find. Please backport to 7.8 as well before FF.

elasticmachine · 2020-06-26T16:37:54Z

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Build Cause: [Pull request #19459 updated]
Start Time: 2020-06-29T21:15:16.314+0000
Duration: 25 min 5 sec

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Test	Results
Failed	0
Passed	543
Skipped	127
Total	670

andrewkroh · 2020-06-26T20:38:35Z

@urso Can you please take another look. My fix triggered race conditions so I took a different approach and dropped in a cancellable context in place of the common.Closer. d77ab50

urso

LGTM.

I consider context and WaitGroup quite low level primitives. They require you to 'track' usage and even free resources (cancel functon MUST be called). We've got some helpers here: https://pkg.go.dev/github.com/elastic/go-concert@v0.0.3/ctxtool?tab=doc, and some kind of with cancelation here: https://pkg.go.dev/github.com/elastic/go-concert?tab=doc#OnceSignaler

The context in Listener could be replaced with OnceSignaler and the stop could be replaced handled via 'WithFunc'.

For higher level primitives managing ownership of groups of go-routines check out the Group interface here: https://pkg.go.dev/github.com/elastic/go-concert@v0.0.3/unison?tab=doc#Group
We've got a sample implementation with TaskGroup. If you keep StopOnError false and do not return an error the implementation perfectly fits this use-case. starting the handler routine would look like this:

l.handlerGroup.Go(func(canceler unison.Canceler) error {
  ctx, cancel := ctxtool.WithFunc(ctxtool.FromCanceller(canceler), func() {
    conn.Close()
  })
  defer cancel()

  defer logp.Recover(...)

  ...

  return nil
})

The group combines shutdown signaling and the WaitGroup when calling 'Stop'. Once 'Stop' has been initiated any attempt to start another handler via Go will return an error, because we are about to shutdown.

urso · 2020-06-29T12:00:37Z

filebeat/inputsource/common/listener.go

The handler go-routine is started always. Let's move cancellation setup local to the that go-routine. Consider to use ctxtool.WithFunc.

Nice, I updated it to use ctxtool.WithFunc.

The tcp and unix input sources were leaking references causing a memory leak. When an accepted connection ended inputsource/common.Closer was supposed to delete the pointer that it held to the connection, but due to a code error `delete` was being called on the wrong map.

The inputsource/common.Closer was managing bidirectional links between parents and children. Anytime you closed an instance it would close all of its children and also remove itself from its parents list of children (this is where the bug was). Every instance has its own mutex. While recursively closing children it was easy to run into a deadlock because the parent holds a lock while closing its children and then the child must edit the parent to remove itself so it also tries to acquire the parent lock. Instead of modifying the common.Closer I replaced it with a cancellable context.Context which is designed to propagate signals from parent to children and requires less code.

ph · 2020-06-29T22:20:23Z

fyi @vjsamuel this might affect you?

vjsamuel · 2020-06-29T23:20:43Z

Thanks. I will need to redo our internal input during the next rebase. Moving to context is the right thing to do however.

…ne-beats * upstream/master: (105 commits) ci: enable packaging job (elastic#19536) ci: disable upstream trigger on PRs for the packaging job (elastic#19490) Implement memlog on-disk handling (elastic#19408) fix go.mod for PR elastic#19423 (elastic#19521) [MetricBeat] add param `aws_partition` to support aws-cn, aws-us-gov regions (elastic#19423) Input v2 stateless manager (elastic#19406) Input v2 compatibility layer (elastic#19401) [Elastic Agent] Fix artifact downloading to allow endpoint-security to be downloaded (elastic#19503) fix: ignore target changes on scans (elastic#19510) Add more helpers to pipeline/testing package (elastic#19405) Report dependencies in CSV format (elastic#19506) [Filebeat] Fix reference leak in TCP and Unix socket inputs (elastic#19459) Cursor input skeleton (elastic#19378) Add changelog. (elastic#19495) [DOC] Typo in Kerberos (elastic#19265) Remove accidentally commited unused NOTICE template (elastic#19485) [Elastic Agent] Support the install, control, and uninstall of Endpoint (elastic#19248) [Filebeat][httpjson] Add split_events_by config setting (elastic#19246) ci: disabling packaging job until we fix it (elastic#19481) Fix golang.org/x/tools to release1.13 (elastic#19478) ...

…19459) The tcp and unix input sources were leaking references causing a memory leak. When an accepted connection ended inputsource/common.Closer was supposed to delete the pointer that it held to the connection, but due to a code error `delete` was being called on the wrong map. Instead of modifying the common.Closer I replaced it with a cancellable context.Context which is designed to propagate signals from parent to children and requires less code. (cherry picked from commit 61f4846)

…19501) The tcp and unix input sources were leaking references causing a memory leak. When an accepted connection ended inputsource/common.Closer was supposed to delete the pointer that it held to the connection, but due to a code error `delete` was being called on the wrong map. Instead of modifying the common.Closer I replaced it with a cancellable context.Context which is designed to propagate signals from parent to children and requires less code. (cherry picked from commit 61f4846)

…nix socket inputs (#19502) * [Filebeat] Fix reference leak in TCP and Unix socket inputs (#19459) The tcp and unix input sources were leaking references causing a memory leak. When an accepted connection ended inputsource/common.Closer was supposed to delete the pointer that it held to the connection, but due to a code error `delete` was being called on the wrong map. Instead of modifying the common.Closer I replaced it with a cancellable context.Context which is designed to propagate signals from parent to children and requires less code. (cherry picked from commit 61f4846) * Update vendor and notice

…19459) The tcp and unix input sources were leaking references causing a memory leak. When an accepted connection ended inputsource/common.Closer was supposed to delete the pointer that it held to the connection, but due to a code error `delete` was being called on the wrong map. Instead of modifying the common.Closer I replaced it with a cancellable context.Context which is designed to propagate signals from parent to children and requires less code.

…P and Unix socket inputs (elastic#19502) * [Filebeat] Fix reference leak in TCP and Unix socket inputs (elastic#19459) The tcp and unix input sources were leaking references causing a memory leak. When an accepted connection ended inputsource/common.Closer was supposed to delete the pointer that it held to the connection, but due to a code error `delete` was being called on the wrong map. Instead of modifying the common.Closer I replaced it with a cancellable context.Context which is designed to propagate signals from parent to children and requires less code. (cherry picked from commit 8eb8ed7) * Update vendor and notice

andrewkroh added bug Filebeat Filebeat needs_backport PR is waiting to be backported to other branches. Team:Services (Deprecated) Label for the former Integrations-Services team labels Jun 26, 2020

botelastic bot added needs_team Indicates that the issue/PR needs a Team:* label and removed needs_team Indicates that the issue/PR needs a Team:* label labels Jun 26, 2020

andrewkroh force-pushed the bugfix/fb/tcp-unix-input-leak branch from 86c05b5 to 11d959c Compare June 26, 2020 14:17

andrewkroh added the review label Jun 26, 2020

andrewkroh marked this pull request as ready for review June 26, 2020 14:17

urso approved these changes Jun 26, 2020

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andrewkroh requested a review from urso June 26, 2020 20:35

andresrc added [zube]: Inbox [zube]: In Review and removed [zube]: Inbox labels Jun 28, 2020

urso reviewed Jun 29, 2020

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andrewkroh added 3 commits June 29, 2020 16:42

Use ctxtool.WithFunc

b524da0

andrewkroh force-pushed the bugfix/fb/tcp-unix-input-leak branch from 96a4155 to b524da0 Compare June 29, 2020 20:42

urso approved these changes Jun 29, 2020

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Update go.sum

b028bb1

andrewkroh merged commit 61f4846 into elastic:master Jun 29, 2020

zube bot added [zube]: Done and removed [zube]: In Review labels Jun 29, 2020

andrewkroh mentioned this pull request Jun 29, 2020

Cherry-pick #19459 to 7.x: [Filebeat] Fix reference leak in TCP and Unix socket inputs #19501

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andrewkroh added v7.9.0 and removed needs_backport PR is waiting to be backported to other branches. labels Jun 29, 2020

andrewkroh mentioned this pull request Jun 29, 2020

Cherry-pick #19459 to 7.8: [Filebeat] Fix reference leak in TCP and Unix socket inputs #19502

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andrewkroh added the v7.8.1 label Jun 29, 2020

andresrc removed the [zube]: Done label Jun 30, 2020

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[Filebeat] Fix reference leak in TCP and Unix socket inputs#19459

[Filebeat] Fix reference leak in TCP and Unix socket inputs#19459
andrewkroh merged 4 commits intoelastic:masterfrom
andrewkroh:bugfix/fb/tcp-unix-input-leak

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andrewkroh commented Jun 26, 2020

What does this PR do?

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