Public issue detail

Runaway CPU investigation for postgres: unknown userspace loop at _dl_map_new_object

postgres is stuck in a likely unclassified userspace loop: 1.70% of sampled CPU passed through _dl_map_new_object, with repeated unlink x14636, read x3248, pread64 x3099.

highpackage: postgresql-18source: postgresql-18score: 106reports: 1

Last seen: 2026-10-11 08:41 UTC. Public JSON: /v1/issues/019fa178-5d37-7e62-babf-fa5fc8594a78

Technical snapshot

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

Representative thread backtrace

  • Command: /usr/lib/postgresql/16/bin/postgres -D /tmp/postgis-pg16.uMtLky/data -F -h -p 31444 -k /tmp/postgis-pg16.uMtLky/socket -c fsync=off -c full_page_writes=off -c synchronous_commit=off
  • 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.
  • Wait site: do_epoll_wait
  • Hot path: _dl_map_new_object (1.70% sampled CPU)
  • Repeated loop: unlink -> unlink -> unlink
  • Top syscalls: unlink x14636, read x3248, pread64 x3099, mmap x2422
  • Kernel: 7.1.8+deb14.1-amd64
  • Distribution: debian
do_epoll_wait
__x64_sys_epoll_wait
do_syscall_64
entry_SYSCALL_64_after_hwframe

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: unknown userspace loop at AtEOXact_Enum

possible duplicate

postgres is stuck in a likely unclassified userspace loop: 100.00% of sampled CPU passed through AtEOXact_Enum, 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 classification, same package, same source package, same subsystem, same target, same wait site

Last seen: 2026-10-22 19:28 UTC. Public page: /issues/019e6423-7fbe-7aa1-8828-2f61e060d90b. Public JSON: /v1/issues/019e6423-7fbe-7aa1-8828-2f61e060d90b

Runaway CPU investigation for postgres: socket churn at _dl_map_new_object

possible duplicate

postgres is stuck in a likely socket churn loop: 3.49% of sampled CPU passed through _dl_map_new_object, with repeated thread backtraces show 1 thread(s) around 0x00007f912645c687 in __GI__IO_flush_all () from target:<path>.

highpackage: postgresql-18source: postgresql-18score: 106reports: 1similarity: 90%

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

Last seen: 2026-10-17 07:40 UTC. Public page: /issues/019f9db1-7511-7382-938c-68a2e3e906c8. Public JSON: /v1/issues/019f9db1-7511-7382-938c-68a2e3e906c8

Runaway CPU investigation for postgres: unknown userspace loop at next_uptodate_folio

possible duplicate

postgres is stuck in a likely unclassified userspace loop: 4.93% of sampled CPU passed through next_uptodate_folio, with repeated no dominant syscall sample was captured.

highpackage: postgresql-18source: linuxscore: 106reports: 2successful triagesimilarity: 89%

Why this looks related: same classification, same package, same subsystem, same target

Last seen: 2026-10-20 02:36 UTC. Public page: /issues/019dcfd5-049e-7413-b236-3e76a8fcb568. Public JSON: /v1/issues/019dcfd5-049e-7413-b236-3e76a8fcb568

Runaway CPU investigation for postgres: file not found retry at _dl_map_new_object

possible duplicate

postgres is stuck in a likely file not found retry loop: 1.58% of sampled CPU passed through _dl_map_new_object, with repeated thread backtraces show 1 thread(s) around 0x00007fb038f9c687 in __GI__IO_flush_all () from target:<path>.

highpackage: postgresql-18source: postgresql-18score: 106reports: 1similarity: 88%

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

Last seen: 2026-10-21 03:01 UTC. Public page: /issues/019f9e46-ed87-7693-a004-3c6b0b260a51. Public JSON: /v1/issues/019f9e46-ed87-7693-a004-3c6b0b260a51

Runaway CPU investigation for postgres: futex lock contention at _dl_map_new_object

possible duplicate

postgres is stuck in a likely futex lock contention loop: 2.64% of sampled CPU passed through _dl_map_new_object, with repeated thread backtraces show 1 thread(s) around 0x00007fa0aa49bca2 in __futex_abstimed_wait_common (futex_word=..., expected=..., clockid=..., abstime=..., private=..., cancel=...) at .<path>:103.

highpackage: postgresql-18source: postgresql-18score: 106reports: 1similarity: 87%

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

Last seen: 2026-10-13 06:02 UTC. Public page: /issues/01a0faf7-676a-70a3-9cf2-63d0f9d56063. Public JSON: /v1/issues/01a0faf7-676a-70a3-9cf2-63d0f9d56063

Runaway CPU investigation for postgres: timer churn at start_dl_timer

possible duplicate

postgres is stuck in a likely timer churn loop: 100.00% of sampled CPU passed through start_dl_timer, with repeated thread backtraces show 1 thread(s) around 0x00007f322d29a7d2 in ?? () from target:<path>.

highpackage: postgresql-18source: postgresql-18score: 106reports: 2similarity: 78%

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

Last seen: 2026-10-22 20:40 UTC. Public page: /issues/019e5d7e-79c8-70a3-bcbd-6d4643b9285a. Public JSON: /v1/issues/019e5d7e-79c8-70a3-bcbd-6d4643b9285a

Published attempts

No public attempts have been published for this issue yet.

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