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| author | Andres Freund <andres@anarazel.de> | 2025-03-24 18:20:18 -0400 |
|---|---|---|
| committer | Andres Freund <andres@anarazel.de> | 2025-03-24 18:20:18 -0400 |
| commit | adb5f85fa5a00d6d5759df55feb16dc22b0fc8d7 (patch) | |
| tree | a65425a8f98628242b91b032d791d7d28dc261fd /src | |
| parent | 7d559c8580f722dc40f2c34573e53e33626679e0 (diff) | |
| download | postgresql-adb5f85fa5a00d6d5759df55feb16dc22b0fc8d7.tar.gz postgresql-adb5f85fa5a00d6d5759df55feb16dc22b0fc8d7.zip | |
Redefine max_files_per_process to control additionally opened files
Until now max_files_per_process=N limited each backend to open N files in
total (minus a safety factor), even if there were already more files opened in
postmaster and inherited by backends. Change max_files_per_process to control
how many additional files each process is allowed to open.
The main motivation for this is the patch to add io_method=io_uring, which
needs to open one file for each backend. Without this patch, even if
RLIMIT_NOFILE is high enough, postmaster will fail in set_max_safe_fds() if
started with a high max_connections. The cause of the failure is that, until
now, set_max_safe_fds() subtracted the already open files from
max_files_per_process.
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/w6uiicyou7hzq47mbyejubtcyb2rngkkf45fk4q7inue5kfbeo@bbfad3qyubvs
Discussion: https://postgr.es/m/CAGECzQQh6VSy3KG4pN1d=h9J=D1rStFCMR+t7yh_Kwj-g87aLQ@mail.gmail.com
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/storage/file/fd.c | 14 | ||||
| -rw-r--r-- | src/backend/utils/misc/guc_tables.c | 2 |
2 files changed, 9 insertions, 7 deletions
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c index 62f1185859f..0c3a2a756e7 100644 --- a/src/backend/storage/file/fd.c +++ b/src/backend/storage/file/fd.c @@ -1047,16 +1047,17 @@ set_max_safe_fds(void) /*---------- * We want to set max_safe_fds to - * MIN(usable_fds, max_files_per_process - already_open) + * MIN(usable_fds, max_files_per_process) * less the slop factor for files that are opened without consulting - * fd.c. This ensures that we won't exceed either max_files_per_process - * or the experimentally-determined EMFILE limit. + * fd.c. This ensures that we won't allow to open more than + * max_files_per_process, or the experimentally-determined EMFILE limit, + * additional files. *---------- */ count_usable_fds(max_files_per_process, &usable_fds, &already_open); - max_safe_fds = Min(usable_fds, max_files_per_process - already_open); + max_safe_fds = Min(usable_fds, max_files_per_process); /* * Take off the FDs reserved for system() etc. @@ -1070,9 +1071,10 @@ set_max_safe_fds(void) ereport(FATAL, (errcode(ERRCODE_INSUFFICIENT_RESOURCES), errmsg("insufficient file descriptors available to start server process"), - errdetail("System allows %d, server needs at least %d.", + errdetail("System allows %d, server needs at least %d, %d files are already open.", max_safe_fds + NUM_RESERVED_FDS, - FD_MINFREE + NUM_RESERVED_FDS))); + FD_MINFREE + NUM_RESERVED_FDS, + already_open))); elog(DEBUG2, "max_safe_fds = %d, usable_fds = %d, already_open = %d", max_safe_fds, usable_fds, already_open); diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 17d28f458f2..989825d3a9c 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -2680,7 +2680,7 @@ struct config_int ConfigureNamesInt[] = { {"max_files_per_process", PGC_POSTMASTER, RESOURCES_KERNEL, - gettext_noop("Sets the maximum number of simultaneously open files for each server process."), + gettext_noop("Sets the maximum number of files each server process is allowed to open simultaneously."), NULL }, &max_files_per_process, |