From f93551a42b9e9ad0da05197d48fac5790474249d Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Mon, 24 Feb 2020 15:39:24 +1300 Subject: [PATCH 02/11] Use a long lived WaitEventSet for WaitLatch(). Create CommonWaitSet at backend startup time, and use it to implement WaitLatch(). This avoids a bunch of epoll/kqueue system calls, and makes sure we don't run into EMFILE later due to lack of file descriptors. Reorder SubPostmasterMain() slightly so that we restore the postmaster pipe and Windows signal before we reach InitPostmasterChild(), to make this work in EXEC_BACKEND builds. Author: Thomas Munro Discussion: https://postgr.es/m/CA%2BhUKGJAC4Oqao%3DqforhNey20J8CiG2R%3DoBPqvfR0vOJrFysGw%40mail.gmail.com --- src/backend/postmaster/postmaster.c | 24 +++++++------- src/backend/storage/ipc/latch.c | 49 +++++++++++++++++++++++++++-- src/backend/utils/init/miscinit.c | 2 ++ src/include/storage/latch.h | 1 + 4 files changed, 61 insertions(+), 15 deletions(-) diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index 46be78aadb..c472971ce0 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -4878,9 +4878,6 @@ SubPostmasterMain(int argc, char *argv[]) IsPostmasterEnvironment = true; whereToSendOutput = DestNone; - /* Setup as postmaster child */ - InitPostmasterChild(); - /* Setup essential subsystems (to ensure elog() behaves sanely) */ InitializeGUCOptions(); @@ -4895,6 +4892,18 @@ SubPostmasterMain(int argc, char *argv[]) /* Close the postmaster's sockets (as soon as we know them) */ ClosePostmasterPorts(strcmp(argv[1], "--forklog") == 0); + /* + * Start our win32 signal implementation. This has to be done after we + * read the backend variables, because we need to pick up the signal pipe + * from the parent process. + */ +#ifdef WIN32 + pgwin32_signal_initialize(); +#endif + + /* Setup as postmaster child */ + InitPostmasterChild(); + /* * Set reference point for stack-depth checking */ @@ -4943,15 +4952,6 @@ SubPostmasterMain(int argc, char *argv[]) if (strcmp(argv[1], "--forkavworker") == 0) AutovacuumWorkerIAm(); - /* - * Start our win32 signal implementation. This has to be done after we - * read the backend variables, because we need to pick up the signal pipe - * from the parent process. - */ -#ifdef WIN32 - pgwin32_signal_initialize(); -#endif - /* In EXEC_BACKEND case we will not have inherited these settings */ pqinitmask(); PG_SETMASK(&BlockSig); diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c index 3b6acfb251..30e461e965 100644 --- a/src/backend/storage/ipc/latch.c +++ b/src/backend/storage/ipc/latch.c @@ -56,6 +56,7 @@ #include "storage/latch.h" #include "storage/pmsignal.h" #include "storage/shmem.h" +#include "utils/memutils.h" /* * Select the fd readiness primitive to use. Normally the "most modern" @@ -129,6 +130,9 @@ struct WaitEventSet #endif }; +/* A common WaitEventSet used to implement WatchLatch() */ +static WaitEventSet *CommonWaitSet; + #ifndef WIN32 /* Are we currently in WaitLatch? The signal handler would like to know. */ static volatile sig_atomic_t waiting = false; @@ -242,6 +246,20 @@ InitializeLatchSupport(void) #endif } +void +InitializeCommonWaitSet(void) +{ + Assert(CommonWaitSet == NULL); + + /* Set up the WaitEventSet used by WaitLatch(). */ + CommonWaitSet = CreateWaitEventSet(TopMemoryContext, 2); + AddWaitEventToSet(CommonWaitSet, WL_LATCH_SET, PGINVALID_SOCKET, + MyLatch, NULL); + if (IsUnderPostmaster) + AddWaitEventToSet(CommonWaitSet, WL_EXIT_ON_PM_DEATH, + PGINVALID_SOCKET, NULL, NULL); +} + /* * Initialize a process-local latch. */ @@ -365,8 +383,29 @@ int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info) { - return WaitLatchOrSocket(latch, wakeEvents, PGINVALID_SOCKET, timeout, - wait_event_info); + WaitEvent event; + + /* Postmaster-managed callers must handle postmaster death somehow. */ + Assert(!IsUnderPostmaster || + (wakeEvents & WL_EXIT_ON_PM_DEATH) || + (wakeEvents & WL_POSTMASTER_DEATH)); + + /* + * Some callers may have a latch other than MyLatch, or want to handle + * postmaster death differently. It's cheap to assign those, so just do it + * every time. + */ + ModifyWaitEvent(CommonWaitSet, 0, WL_LATCH_SET, latch); + CommonWaitSet->exit_on_postmaster_death = + ((wakeEvents & WL_EXIT_ON_PM_DEATH) != 0); + + if (WaitEventSetWait(CommonWaitSet, + (wakeEvents & WL_TIMEOUT) ? timeout : -1, + &event, 1, + wait_event_info) == 0) + return WL_TIMEOUT; + else + return event.events; } /* @@ -700,7 +739,11 @@ FreeWaitEventSet(WaitEventSet *set) ReleaseExternalFD(); #elif defined(WAIT_USE_KQUEUE) close(set->kqueue_fd); - ReleaseExternalFD(); + if (set->kqueue_fd >= 0) + { + close(set->kqueue_fd); + ReleaseExternalFD(); + } #elif defined(WAIT_USE_WIN32) WaitEvent *cur_event; diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c index cd099b0c70..1cace9735d 100644 --- a/src/backend/utils/init/miscinit.c +++ b/src/backend/utils/init/miscinit.c @@ -109,6 +109,7 @@ InitPostmasterChild(void) InitializeLatchSupport(); MyLatch = &LocalLatchData; InitLatch(MyLatch); + InitializeCommonWaitSet(); /* * If possible, make this process a group leader, so that the postmaster @@ -141,6 +142,7 @@ InitStandaloneProcess(const char *argv0) InitializeLatchSupport(); MyLatch = &LocalLatchData; InitLatch(MyLatch); + InitializeCommonWaitSet(); /* Compute paths, no postmaster to inherit from */ if (my_exec_path[0] == '\0') diff --git a/src/include/storage/latch.h b/src/include/storage/latch.h index 46ae56cae3..ec1865a8fd 100644 --- a/src/include/storage/latch.h +++ b/src/include/storage/latch.h @@ -176,6 +176,7 @@ extern int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info); extern int WaitLatchOrSocket(Latch *latch, int wakeEvents, pgsocket sock, long timeout, uint32 wait_event_info); +extern void InitializeCommonWaitSet(void); /* * Unix implementation uses SIGUSR1 for inter-process signaling. -- 2.18.2