Public issue detail

Runaway CPU investigation for postgres: unknown userspace loop at copy_mc_enhanced_fast_string

postgres is stuck in a likely unclassified userspace loop: 8.04% of sampled CPU passed through copy_mc_enhanced_fast_string, with repeated thread backtraces show 1 thread(s) around 0x00007f322d29a7d2 in ?? () from target:<path>.

highpackage: postgresql-18source: postgresql-18score: 106reports: 2

Last seen: 2026-06-19 22:52 UTC. Public JSON: /v1/issues/019d3a09-5e64-7760-9352-5f8143305bc8

Technical snapshot

This is the clearest retained userspace thread cluster Fixer captured while the process was spinning.

Representative thread backtrace

  • Command: /usr/lib/postgresql/18/bin/postgres -D /var/lib/postgresql/18/main -c config_file=/etc/postgresql/18/main/postgresql.conf
  • Why Fixer classified it this way: The process is demonstrably CPU-hot, but the current syscall and symbol sample does not point to a single dominant loop family yet.
  • Thread summary: thread backtraces show 1 thread(s) around 0x00007f322d29a7d2 in ?? () from target:<path>
  • Contention signals: event-loop-wakeups, gdb-stderr: gdb: warning: Couldn't determine a path for the index cache directory. warning: .dynamic section for "target:<path>++.so.6" is not at the expected address (wrong library or version mismatch?)
  • Repeated loop: read -> read -> read
  • Top syscalls: read x54, close x12, rt_sigaction x11, openat x9
  • Package: postgresql-18 18.3-1.pgdg+2
  • Kernel: 6.17.10+deb14-amd64
  • Distribution: debian
0x00007f322d29a7d2 in ?? () from target:<path>
0x00007f322d29a7ed in ?? () from target:<path>
0x00007f322d31d0cd in epoll_wait () from target:<path>
0x00005574dfc994fa in WaitEventSetWait ()
0x00005574dfc02498 in ?? ()
0x00005574dfc04e45 in PostmasterMain ()
0x00005574df8a335a in main ()

Possible duplicates

These are suggestions based on sanitized trigram similarity plus structured fields like package, subsystem, classification, and wait site. They are not auto-merged.

Runaway CPU investigation for postgres: busy poll at copy_mc_enhanced_fast_string

possible duplicate

postgres is stuck in a likely busy poll loop: 13.49% of sampled CPU passed through copy_mc_enhanced_fast_string, with repeated thread backtraces show 1 thread(s) around 0x00007f322d29a7d2 in ?? () from target:<path>.

highpackage: postgresql-18source: postgresql-18score: 106reports: 2successful triagesimilarity: 99%

Why this looks related: same package, same source package, same subsystem, same target, same wait site, very similar public summary

Last seen: 2026-06-27 04:49 UTC. Public page: /issues/019db559-5b5d-7021-ab89-da27daafa4b3. Public JSON: /v1/issues/019db559-5b5d-7021-ab89-da27daafa4b3

Runaway CPU investigation for postgres: unknown userspace loop at do_fault

possible duplicate

postgres is stuck in a likely unclassified userspace loop: 50.00% of sampled CPU passed through do_fault, with repeated thread backtraces show 1 thread(s) around 0x00007f33aba9a7d2 in ?? () from target:<path>.

highpackage: postgresql-18source: postgresql-18score: 106reports: 1similarity: 99%

Why this looks related: same classification, same package, same source package, same subsystem, same target, same wait site

Last seen: 2026-07-08 12:09 UTC. Public page: /issues/019f077a-7a30-78d1-b552-06c90a00dbb0. Public JSON: /v1/issues/019f077a-7a30-78d1-b552-06c90a00dbb0

Runaway CPU investigation for postgres: busy poll at next_uptodate_folio

possible duplicate

postgres is stuck in a likely busy poll loop: 20.28% of sampled CPU passed through next_uptodate_folio, with repeated thread backtraces show 1 thread(s) around 0x00007f322d29a7d2 in ?? () from target:<path>.

highpackage: postgresql-18source: postgresql-18score: 106reports: 2successful triagesimilarity: 84%

Why this looks related: same package, same source package, same subsystem, same target, same wait site

Last seen: 2026-06-27 02:02 UTC. Public page: /issues/019dd9b3-4d4e-73f0-86bb-bf7e642a5785. Public JSON: /v1/issues/019dd9b3-4d4e-73f0-86bb-bf7e642a5785

Runaway CPU investigation for llmfit: unknown userspace loop at <&ratatui_core::text::span::Span as ratatui_core::widgets::widget::Widg…

possible duplicate

llmfit is stuck in a likely unclassified userspace loop: 10.54% of sampled CPU passed through <&ratatui_core::text::span::Span as ratatui_core::widgets::wi..., with repeated thread backtraces show 1 thread(s) around 0x00007fb47b894bf6 in sccp ().

highscore: 106reports: 1similarity: 70%

Why this looks related: same classification, same subsystem, same wait site

Last seen: 2026-07-08 11:50 UTC. Public page: /issues/019ed1fd-2fcf-7a10-b2e6-e2656b4f763e. Public JSON: /v1/issues/019ed1fd-2fcf-7a10-b2e6-e2656b4f763e

Runaway CPU investigation for smtpd: busy poll at unix_maybe_add_creds

possible duplicate

smtpd is stuck in a likely busy poll loop: 14.11% of sampled CPU passed through unix_maybe_add_creds, with repeated thread backtraces show 1 thread(s) around 0x00007f529799e7d2 in ?? () from target:<path>.

highpackage: postfixsource: postfixscore: 106reports: 1similarity: 46%

Why this looks related: same subsystem, same wait site

Last seen: 2026-07-04 06:14 UTC. Public page: /issues/019ec5c3-2f99-7ea0-9bcc-7718d776a285. Public JSON: /v1/issues/019ec5c3-2f99-7ea0-9bcc-7718d776a285

Published attempts

No public attempts have been published for this issue yet.

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