database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-30 11:03:19 +03:00
Code Activity

Add a new shmem_request_hook hook.

Browse Source 
Currently, preloaded libraries are expected to request additional
shared memory and LWLocks in _PG_init().  However, it is not unusal
for such requests to depend on MaxBackends, which won't be
initialized at that time.  Such requests could also depend on GUCs
that other modules might change.  This introduces a new hook where
modules can safely use MaxBackends and GUCs to request additional
shared memory and LWLocks.

Furthermore, this change restricts requests for shared memory and
LWLocks to this hook.  Previously, libraries could make requests
until the size of the main shared memory segment was calculated.
Unlike before, we no longer silently ignore requests received at
invalid times.  Instead, we FATAL if someone tries to request
additional shared memory or LWLocks outside of the hook.

Nathan Bossart and Julien Rouhaud

Discussion: https://postgr.es/m/20220412210112.GA2065815%40nathanxps13
Discussion: https://postgr.es/m/Yn2jE/lmDhKtkUdr@paquier.xyz
This commit is contained in:
Robert Haas
2022-05-13 09:31:06 -04:00
parent 8c8d307f82
commit 4f2400cb3f
9 changed files with 81 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
contrib/pg_prewarm/autoprewarm.c
View File

@ -96,6 +96,8 @@ static void apw_start_database_worker(void);
static bool apw_init_shmem(void);
static void apw_detach_shmem(int code, Datum arg);
static int apw_compare_blockinfo(const void *p, const void *q);
static void autoprewarm_shmem_request(void);
static shmem_request_hook_type prev_shmem_request_hook = NULL;
/* Pointer to shared-memory state. */
static AutoPrewarmSharedState *apw_state = NULL;
@ -139,13 +141,26 @@ _PG_init(void)
MarkGUCPrefixReserved("pg_prewarm");
RequestAddinShmemSpace(MAXALIGN(sizeof(AutoPrewarmSharedState)));
prev_shmem_request_hook = shmem_request_hook;
shmem_request_hook = autoprewarm_shmem_request;
/* Register autoprewarm worker, if enabled. */
if (autoprewarm)
apw_start_leader_worker();
}
/*
* Requests any additional shared memory required for autoprewarm.
*/
static void
autoprewarm_shmem_request(void)
{
if (prev_shmem_request_hook)
prev_shmem_request_hook();
RequestAddinShmemSpace(MAXALIGN(sizeof(AutoPrewarmSharedState)));
}
/*
* Main entry point for the leader autoprewarm process. Per-database workers
* have a separate entry point.