From f1faa31a43ac7365d7681c01fe39977469bfe107 Mon Sep 17 00:00:00 2001 From: Fujii Masao Date: Fri, 25 Jul 2025 09:50:35 +0900 Subject: [PATCH v2] Fix background worker not restarting after crash-and-restart cycle. Previously, if a background worker crashed (e.g., due to a SIGKILL) and the server restarted due to restart_after_crash being enabled, the worker was not restarted as expected. Background workers without the never-restart flag should automatically restart in this case. This issue was introduced in commit 28a520c0b77, which failed to reset the rw_pid field in the RegisteredBgWorker struct for the crashed worker. This commit fixes the problem by resetting rw_pid for all eligible background workers during the crash-and-restart cycle. Back-patched to v18, where the bug was introduced. Bug fix patches were proposed by Andrey Rudometov and ChangAo Chen, but this commit uses a different approach. Reported-by: Andrey Rudometov Reported-by: ChangAo Chen Author: Andrey Rudometov Author: ChangAo Chen Co-authored-by: Fujii Masao Reviewed-by: Shveta Malik Discussion: https://postgr.es/m/CAF6JsWiO=i24qYitWe6ns1sXqcL86rYxdyU+pNYk-WueKPSySg@mail.gmail.com Discussion: https://postgr.es/m/tencent_E00A056B3953EE6440F0F40F80EC30427D09@qq.com Backpatch-through: 18 --- src/backend/postmaster/bgworker.c | 1 + src/backend/postmaster/postmaster.c | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c index 116ddf7b835..1ad65c237c3 100644 --- a/src/backend/postmaster/bgworker.c +++ b/src/backend/postmaster/bgworker.c @@ -613,6 +613,7 @@ ResetBackgroundWorkerCrashTimes(void) * resetting. */ rw->rw_crashed_at = 0; + rw->rw_pid = 0; /* * If there was anyone waiting for it, they're history. diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index cca9b946e53..e01d9f0cfe8 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -2630,6 +2630,13 @@ CleanupBackend(PMChild *bp, } bp = NULL; + /* + * In a crash case, exit immediately without resetting background worker + * state. However, if restart_after_crash is enabled, the background + * worker state (e.g., rw_pid) still needs be reset so the worker can + * restart after crash recovery. This reset is handled in + * ResetBackgroundWorkerCrashTimes(), not here. + */ if (crashed) { HandleChildCrash(bp_pid, exitstatus, procname); -- 2.50.1