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Guard metrics collector with mutex#186

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ghdrope wants to merge 4 commits into
kcp-dev:mainfrom
ghdrope:160-guard-MetricsCollector-with-mutex
Open

Guard metrics collector with mutex#186
ghdrope wants to merge 4 commits into
kcp-dev:mainfrom
ghdrope:160-guard-MetricsCollector-with-mutex

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@ghdrope ghdrope commented Mar 28, 2026 •
edited by xrstf
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Summary

Make MetricsCollector thread-safe and prevent metric disappearance during Prometheus scrapes by adding a sync.RWMutex and a Collect() method.

Note: Also added defer ticker.Stop() and commenting.

What Type of PR Is This?

/kind bug
/kind cleanup
/kind documentation

Related Issue(s)

Fixes #160

Release Notes

MetricsCollector is now thread-safe.

@kcp-ci-bot kcp-ci-bot added kind/bug Categorizes issue or PR as related to a bug. release-note Denotes a PR that will be considered when it comes time to generate release notes. kind/cleanup Categorizes issue or PR as related to cleaning up code, process, or technical debt. dco-signoff: yes Indicates the PR's author has signed the DCO. kind/documentation Categorizes issue or PR as related to documentation. labels Mar 28, 2026
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kcp-ci-bot commented Mar 28, 2026

Hi @ghdrope. Thanks for your PR.

I'm waiting for a kcp-dev member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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@kcp-ci-bot kcp-ci-bot added needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Mar 28, 2026
@ghdrope ghdrope force-pushed the 160-guard-MetricsCollector-with-mutex branch from 9dc680a to 08a7ba4 Compare March 28, 2026 13:25
ntnn
ntnn approved these changes Mar 29, 2026
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/lgtm

Thank you!

/assign @xrstf

@kcp-ci-bot kcp-ci-bot added the lgtm Indicates that a PR is ready to be merged. label Mar 29, 2026
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kcp-ci-bot commented Mar 29, 2026

LGTM label has been added.

DetailsGit tree hash: d32980f2f59971dadc8e8dbf6189ef948b725759

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ntnn commented Mar 29, 2026

/ok-to-test

@kcp-ci-bot kcp-ci-bot added ok-to-test Indicates a non-member PR verified by an org member that is safe to test. and removed needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Mar 29, 2026
@ntnn ntnn added this to tbd Mar 29, 2026
@github-project-automation github-project-automation Bot moved this to Backlog in tbd Mar 29, 2026
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ntnn commented Mar 29, 2026

/retest

infra failure

 failed to connect to the docker API at unix:///var/run/docker.sock; check if the path is correct and if the daemon is running: dial unix /var/run/docker.sock: connect: no such file or directory

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ghdrope commented Mar 30, 2026

/retest

xrstf
xrstf reviewed Mar 30, 2026
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Comment thread internal/metrics/collector.go Outdated
xrstf
xrstf reviewed Mar 30, 2026
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@ghdrope ghdrope force-pushed the 160-guard-MetricsCollector-with-mutex branch from 08a7ba4 to dc60979 Compare March 30, 2026 22:36
@kcp-ci-bot kcp-ci-bot removed the lgtm Indicates that a PR is ready to be merged. label Mar 30, 2026
@kcp-ci-bot kcp-ci-bot requested review from ntnn and xrstf March 30, 2026 22:36
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kcp-ci-bot commented Mar 30, 2026

New changes are detected. LGTM label has been removed.

@ntnn ntnn moved this from Backlog to Reviewing in tbd Mar 31, 2026
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xrstf commented Apr 1, 2026

/retest

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ghdrope commented Apr 2, 2026

/retest

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mjudeikis commented Apr 8, 2026

/retest

@kcp-ci-bot kcp-ci-bot added the needs-rebase Indicates a PR cannot be merged because it has merge conflicts with HEAD. label Apr 8, 2026
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ntnn commented Apr 21, 2026

@ghdrope Could you rebase the pr? Thanks!

@xrstf xrstf changed the title 160 guard metrics collector with mutex Guard metrics collector with mutex Apr 21, 2026
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xrstf commented Apr 21, 2026

/remove-kind documentation

@kcp-ci-bot kcp-ci-bot removed the kind/documentation Categorizes issue or PR as related to documentation. label Apr 21, 2026
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ghdrope commented Apr 21, 2026

I lost track of this one, my bad. Sure, I can rebase it @ntnn, I’ll do it later today after work hours.

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kcp-ci-bot commented Apr 21, 2026

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please ask for approval from ntnn. For more information see the Code Review Process.

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@kcp-ci-bot kcp-ci-bot added size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. and removed size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Apr 21, 2026
ghdrope and others added 3 commits April 22, 2026 00:19
@ghdrope
collector: make MetricsCollector thread-safe with RWMutex
b4f0279 
Signed-off-by: ghdrope <0coasts-gearing@icloud.com>
@ghdrope
docs: add comments to MetricsCollector methods
ec40abd 
Signed-off-by: ghdrope <0coasts-gearing@icloud.com>
@xrstf @ghdrope
Implement initial support for external virtual workspaces (kcp-dev#193)
2481b41 
* implement initial support for external virtual workspaces

On-behalf-of: @SAP christoph.mewes@sap.com

* use unrealistically low resource requests to help squeeze more out of our CI nodes

* PR feedback from Copilot
@ghdrope ghdrope force-pushed the 160-guard-MetricsCollector-with-mutex branch from 4236a41 to 6dd1750 Compare April 21, 2026 22:30
@kcp-ci-bot kcp-ci-bot added size/M Denotes a PR that changes 30-99 lines, ignoring generated files. and removed needs-rebase Indicates a PR cannot be merged because it has merge conflicts with HEAD. size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. labels Apr 21, 2026
@ghdrope
docs: add comments to MetricsCollector methods
f9034fc 
Signed-off-by: ghdrope <0coasts-gearing@icloud.com>
@ghdrope ghdrope force-pushed the 160-guard-MetricsCollector-with-mutex branch from 6dd1750 to f9034fc Compare April 22, 2026 07:09
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ghdrope commented Apr 22, 2026

Tests passed 😃 @ntnn @xrstf please take a look when you have time, and let me know if any changes are needed.
Thank you!

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xrstf commented Apr 22, 2026

Now that I look at it, are we even sure the Collect() function is called? From what I can see in the main(), each individual metric is registered with the default collector, and our MetricsCollector is purely a goroutine to update those metrics. I do not think the mutex will actually do anything right now, unless we use our MetricsCollector as a "native" Prometheus collector, no?

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metrics: guard MetricsCollector with a mutex to prevent transient scrape gaps

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