fix(net): pad GetExtendedTcpTable buffer to prevent GC thrashing on Windows by HarshalPatel1972 · Pull Request #2108 · shirou/gopsutil

HarshalPatel1972 · 2026-06-30T13:26:58Z

Problem

Under heavy network load, querying the Windows TCP/UDP tables can trigger a near-infinite ERROR_INSUFFICIENT_BUFFER spin-loop. Because the Go wrapper naively allocates the exact required size returned by the Win32 API, any new connections spawned by the OS before the next iteration cause the subsequent API call to fail again. This rapid, tight reallocation cycle completely overwhelms the Go Garbage Collector, mimicking a severe memory leak and causing massive CPU spikes.

Fix

Added a 4KB (4096 byte) padding to the requested size before reallocating the buffer in both getTCPConnections and getUDPConnections.
This padding safely absorbs concurrent connection growth between the failed API call and the next iteration, allowing the retry loop to exit cleanly and preventing GC thrashing.

Verification

Validated via go test -v ./net/.... Struct alignment and parsing remain intact.

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Under heavy load, querying the Windows TCP/UDP tables can trigger an infinite ERROR_INSUFFICIENT_BUFFER loop. Because the exact required size is allocated, any new connections spawned before the next iteration cause the call to fail again. This rapid reallocation cycle overwhelms the Go GC, mimicking a severe memory leak. Adding a 4KB padding buffer to the requested size absorbs concurrent connection growth, allowing the retry loop to succeed and preventing GC thrashing. Signed-off-by: Harshal Patel <hp842484@gmail.com>

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Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

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shirou · 2026-07-02T14:57:13Z

Thanks for the fix! The approach makes sense. One thing:

Could you make the TCP and UDP changes consistent? Copilot's comment about the uint32 overflow applies to both paths, but the guard was only added on the TCP side. Personally I'd lean toward dropping the guard in both places — a table size near 4 GiB can't realistically happen, and on 32-bit builds make would panic above MaxInt32 before the guard helps anyway. But if you prefer keeping it, please add the same guard (with the shared constant) to the UDP side too.

Optionally, a small retry limit on the loop might be worth considering, since very heavy churn could in theory still keep it spinning.

HarshalPatel1972 · 2026-07-04T11:15:13Z

Thanks for the fix! The approach makes sense. One thing:

Could you make the TCP and UDP changes consistent? Copilot's comment about the uint32 overflow applies to both paths, but the guard was only added on the TCP side. Personally I'd lean toward dropping the guard in both places — a table size near 4 GiB can't realistically happen, and on 32-bit builds make would panic above MaxInt32 before the guard helps anyway. But if you prefer keeping it, please add the same guard (with the shared constant) to the UDP side too.

Optionally, a small retry limit on the loop might be worth considering, since very heavy churn could in theory still keep it spinning.

@shirou Thanks for the feedback!

You are completely right about the uint32 overflow guard being overkill. I've just pushed a new commit that rips it out entirely, making the TCP and UDP logic perfectly consistent.

I also took your advice and wrapped both buffer allocation loops with a hard 10-retry limit (for retry := 0; retry < 10; retry++). If the OS manages to churn the TCP/UDP tables so violently that we can't allocate a sufficient buffer after 10 tries, it now cleanly bails out with an error rather than spinning infinitely.

Let me know if this looks good to merge.

Signed-off-by: Harshal Patel <hp842484@gmail.com>

shirou

Thanks for the update. LGTM! I appreciate your contribution!

HarshalPatel1972 · 2026-07-11T11:36:09Z

Thanks for the update. LGTM! I appreciate your contribution!

Thanks for the guidance throughout.

…p ci] Bumps the go-modules group in /e2e-go with 2 updates: [github.com/moby/go-archive](https://github.com/moby/go-archive) and [github.com/shirou/gopsutil/v4](https://github.com/shirou/gopsutil). Updates `github.com/moby/go-archive` from 0.2.1 to 0.3.2 Release notes *Sourced from [github.com/moby/go-archive's releases](https://github.com/moby/go-archive/releases).* > v0.3.2 > ------ > > What's Changed > -------------- > > Fix a regression introduced in v0.3.0 that caused archive extraction to fail when paths traversed absolute symlinks inside the destination root, such as `var/run -> /run`. Absolute symlink targets are now resolved relative to the extraction root while relative symlink escapes remain rejected. [moby/go-archive#93](https://redirect.github.com/moby/go-archive/pull/93) > > **Full Changelog**: <moby/go-archive@v0.3.1...v0.3.2> > > v0.3.1 > ------ > > Fixes > ----- > > This patch release fixes a regression introduced in v0.2.1 where archive extraction could fail when an archive omitted explicit entries for parent directories. For example, extracting `etc/dnf/` without a preceding `etc/` entry could return `mkdirat etc/dnf: no such file or directory`. > > This prevented affected images from being extracted. Archive extraction now creates implied parent directories for both file and directory entries. > > What's Changed > -------------- > > * archive: create implied parents for directory entries [moby/go-archive#92](https://redirect.github.com/moby/go-archive/pull/92) > * archive: Tarballer.Go: suppress io.ErrClosedPipe logs on close [moby/go-archive#94](https://redirect.github.com/moby/go-archive/pull/94) > > **Full Changelog**: <moby/go-archive@v0.3.0...v0.3.1> > > v0.3.0 > ------ > > Security > -------- > > This release fixes **CVE-2026-17106** / **[GHSA-hfg8-hc9c-6c3h](https://github.com/moby/go-archive/security/advisories/GHSA-hfg8-hc9c-6c3h)**, where a crafted tar archive could use links to cause extraction operations to create or overwrite files outside the intended destination directory. > > The issue affected `Unpack`, `UnpackLayer`, `Untar`, `UntarUncompressed`, and the `ApplyLayer` helpers. Users should upgrade and avoid extracting untrusted archives with earlier versions. > > What's Changed > -------------- > > * archive: harden tar extraction against path traversal [moby/go-archive#45](https://redirect.github.com/moby/go-archive/pull/45) > * archive: do not follow reparse points in chtimes [moby/go-archive#90](https://redirect.github.com/moby/go-archive/pull/90) > * archive: fix creation time updates on Windows [moby/go-archive#79](https://redirect.github.com/moby/go-archive/pull/79) > * archive: minor cleanups and godoc touch-up [moby/go-archive#87](https://redirect.github.com/moby/go-archive/pull/87) > * archive: RebaseArchiveEntries: fix archive path rebasing [moby/go-archive#43](https://redirect.github.com/moby/go-archive/pull/43) > > Test and CI changes > ------------------- > > * ci: enable dependabot for actions [moby/go-archive#81](https://redirect.github.com/moby/go-archive/pull/81) > * archive: make breakoutErr unwrap its cause [moby/go-archive#91](https://redirect.github.com/moby/go-archive/pull/91) > * archive: use filepath for filesystem paths in tests [moby/go-archive#80](https://redirect.github.com/moby/go-archive/pull/80) > * archive: use filepath for filesystem paths in tests [moby/go-archive#80](https://redirect.github.com/moby/go-archive/pull/80) > > **Full Changelog**: <moby/go-archive@v0.2.1...v0.3.0> Commits * [`9e6d2c7`](moby/go-archive@9e6d2c7) Merge pull request [#93](https://redirect.github.com/moby/go-archive/issues/93) from thaJeztah/fix\_absolute\_symlinks * [`4f6cd58`](moby/go-archive@4f6cd58) archive: resolve hardlinks through absolute symlinks * [`e564ecc`](moby/go-archive@e564ecc) archive: resolve absolute symlinks within extraction root * [`5bb8a45`](moby/go-archive@5bb8a45) Merge pull request [#94](https://redirect.github.com/moby/go-archive/issues/94) from thaJeztah/denoise * [`1bec7ec`](moby/go-archive@1bec7ec) archive: Tarballer.Go: suppress io.ErrClosedPipe logs on close * [`279fa6d`](moby/go-archive@279fa6d) Merge pull request [#92](https://redirect.github.com/moby/go-archive/issues/92) from thaJeztah/fix\_implied\_directories * [`517985a`](moby/go-archive@517985a) archive: create implied parents for directory entries * [`1c23372`](moby/go-archive@1c23372) Merge pull request [#43](https://redirect.github.com/moby/go-archive/issues/43) from thaJeztah/fix\_rebase\_from\_root * [`8829a25`](moby/go-archive@8829a25) RebaseArchiveEntries: fix archive path rebasing * [`c583b20`](moby/go-archive@c583b20) Merge pull request [#90](https://redirect.github.com/moby/go-archive/issues/90) from thaJeztah/chtimes\_nofollow * Additional commits viewable in [compare view](moby/go-archive@v0.2.1...v0.3.2) Updates `github.com/shirou/gopsutil/v4` from 4.26.6 to 4.26.7 Release notes *Sourced from [github.com/shirou/gopsutil/v4's releases](https://github.com/shirou/gopsutil/releases).* > v4.26.7 > ------- > > What's Changed > -------------- > > ### cpu > > * fix: harden parsers against malformed/truncated input by [`@shirou`](https://github.com/shirou) in [shirou/gopsutil#2109](https://redirect.github.com/shirou/gopsutil/pull/2109) > * [cpu][windows]: compute cpu-total times from integer ticks by [`@skartikey`](https://github.com/skartikey) in [shirou/gopsutil#2111](https://redirect.github.com/shirou/gopsutil/pull/2111) > * [darwin][process]: fix errno handling and library lifetime on darwin by [`@shirou`](https://github.com/shirou) in [shirou/gopsutil#2119](https://redirect.github.com/shirou/gopsutil/pull/2119) > * [cpu][windows]: compute total counters from individual stats to handle processor groups correctly by [`@srebhan`](https://github.com/srebhan) in [shirou/gopsutil#2125](https://redirect.github.com/shirou/gopsutil/pull/2125) > * [cpu][windows]: harden the cpu-total computation added in [#2125](https://redirect.github.com/shirou/gopsutil/issues/2125) by [`@shirou`](https://github.com/shirou) in [shirou/gopsutil#2128](https://redirect.github.com/shirou/gopsutil/pull/2128) > > ### net > > * fix(net): pad GetExtendedTcpTable buffer to prevent GC thrashing on Windows by [`@HarshalPatel1972`](https://github.com/HarshalPatel1972) in [shirou/gopsutil#2108](https://redirect.github.com/shirou/gopsutil/pull/2108) > > ### process > > * process: implement Darwin IOCounters via proc\_pid\_rusage by [`@DavRack`](https://github.com/DavRack) in [shirou/gopsutil#2117](https://redirect.github.com/shirou/gopsutil/pull/2117) > > ### other > > * feat: add psutil comparison tests for cpu, mem and load by [`@shirou`](https://github.com/shirou) in [shirou/gopsutil#2114](https://redirect.github.com/shirou/gopsutil/pull/2114) > > New Contributors > ---------------- > > * [`@DavRack`](https://github.com/DavRack) made their first contribution in [shirou/gopsutil#2117](https://redirect.github.com/shirou/gopsutil/pull/2117) > * [`@srebhan`](https://github.com/srebhan) made their first contribution in [shirou/gopsutil#2125](https://redirect.github.com/shirou/gopsutil/pull/2125) > > **Full Changelog**: <shirou/gopsutil@v4.26.6...v4.26.7> Commits * [`52a24c8`](shirou/gopsutil@52a24c8) Merge pull request [#2128](https://redirect.github.com/shirou/gopsutil/issues/2128) from shirou/feat/follow-up-2125 * [`268a953`](shirou/gopsutil@268a953) [cpu][windows]: harden the cpu-total computation added in [#2125](https://redirect.github.com/shirou/gopsutil/issues/2125) * [`1e34da6`](shirou/gopsutil@1e34da6) Merge pull request [#2125](https://redirect.github.com/shirou/gopsutil/issues/2125) from srebhan/fix\_cpu\_windows\_total * [`61f8802`](shirou/gopsutil@61f8802) Merge pull request [#2122](https://redirect.github.com/shirou/gopsutil/issues/2122) from shirou/dependabot/github\_actions/actions/checko... * [`7fb4dcf`](shirou/gopsutil@7fb4dcf) Merge pull request [#2123](https://redirect.github.com/shirou/gopsutil/issues/2123) from shirou/dependabot/github\_actions/actions/setup-... * [`ae7d91a`](shirou/gopsutil@ae7d91a) Merge pull request [#2119](https://redirect.github.com/shirou/gopsutil/issues/2119) from shirou/fix/darwin-errno-and-libcache * [`49052a1`](shirou/gopsutil@49052a1) [darwin][process]: use a PID above PID\_MAX in the not-running tests * [`991b238`](shirou/gopsutil@991b238) [darwin]: pass the remaining Go pointers as unsafe.Pointer on darwin * [`b9930e2`](shirou/gopsutil@b9930e2) Merge pull request [#2124](https://redirect.github.com/shirou/gopsutil/issues/2124) from shirou/dependabot/github\_actions/actions/labele... * [`38a01b4`](shirou/gopsutil@38a01b4) [cpu][windows]: compute total counters from individual stats to handle proces... * Additional commits viewable in [compare view](shirou/gopsutil@v4.26.6...v4.26.7) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. 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[//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- Dependabot commands and options You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot show ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore major version` will close this group update PR and stop Dependabot creating any more for the specific dependency's major version (unless you unignore this specific dependency's major version or upgrade to it yourself) - `@dependabot ignore minor version` will close this group update PR and stop Dependabot creating any more for the specific dependency's minor version (unless you unignore this specific dependency's minor version or upgrade to it yourself) - `@dependabot ignore ` will close this group update PR and stop Dependabot creating any more for the specific dependency (unless you unignore this specific dependency or upgrade to it yourself) - `@dependabot unignore ` will remove all of the ignore conditions of the specified dependency - `@dependabot unignore ` will remove the ignore condition of the specified dependency and ignore conditions

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github-actions Bot added os:windows package:net labels Jun 30, 2026

HarshalPatel1972 force-pushed the patch-gopsutil branch from 5d8e292 to 7c2f0ed Compare June 30, 2026 13:31

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net: standardize padding logic and add retry limit for GetExtendedTable

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Signed-off-by: Harshal Patel <hp842484@gmail.com>

HarshalPatel1972 force-pushed the patch-gopsutil branch from 3effa6a to 3d799ff Compare July 4, 2026 11:17

shirou approved these changes Jul 11, 2026

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shirou merged commit b6da089 into shirou:master Jul 11, 2026
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fix(net): pad GetExtendedTcpTable buffer to prevent GC thrashing on Windows - #2108

fix(net): pad GetExtendedTcpTable buffer to prevent GC thrashing on Windows#2108
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HarshalPatel1972 commented Jun 30, 2026

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