Hello, In commits 9f095299 and f98b8476 we improved recovery performance on Linux and FreeBSD but we didn't help other operating systems. David just confirmed for me that commenting out the PostmasterIsAlive() call in the main recovery loop speeds up crash recovery considerably on his Windows system: 93s -> 70s or 1.32x faster. So I think we should do something like what Heikki originally proposed to lower the frequency of checks, on systems where we don't have the ability to skip the check completely. Please see attached.
From a602b79a354bcfea75494c62c3dd9dee7dd8fa9e Mon Sep 17 00:00:00 2001 From: Thomas Munro <thomas.mu...@gmail.com> Date: Thu, 17 Sep 2020 21:11:01 +1200 Subject: [PATCH] Poll postmaster less frequently in recovery.
Since commits 9f095299 and f98b8476 we don't poll the postmaster pipe/event at all during recovery on Linux and FreeBSD, but on other operating systems we were still doing it for every WAL record. Do it less frequently on operating systems where system calls are still required, at the cost of delaying shutdown a bit after postmaster death, to avoid expensive system calls known to slow down CPU-bound recovery by 10-30%. Discussion: https://postgr.es/m/7261eb39-0369-f2f4-1bb5-62f3b6083...@iki.fi --- src/backend/postmaster/startup.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c index fd9ac35dac..2ef5da6908 100644 --- a/src/backend/postmaster/startup.c +++ b/src/backend/postmaster/startup.c @@ -134,6 +134,10 @@ StartupRereadConfig(void) void HandleStartupProcInterrupts(void) { +#ifndef USE_POSTMASTER_DEATH_SIGNAL + static int count = 0; +#endif + /* * Process any requests or signals received recently. */ @@ -151,9 +155,15 @@ HandleStartupProcInterrupts(void) /* * Emergency bailout if postmaster has died. This is to avoid the - * necessity for manual cleanup of all postmaster children. + * necessity for manual cleanup of all postmaster children. Do this less + * frequently on systems for which we don't have signals to make that + * cheap. */ - if (IsUnderPostmaster && !PostmasterIsAlive()) + if (IsUnderPostmaster && +#ifndef USE_POSTMASTER_DEATH_SIGNAL + count++ % 1024 == 0 && +#endif + !PostmasterIsAlive()) exit(1); /* Process barrier events */ -- 2.20.1
