From bcd5bdfee416c175f58612d587f7b6fbe7435fd8 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Fri, 15 Nov 2019 14:40:23 -0500 Subject: [PATCH] Add a pg_shmem_allocations view. It tells you how the main shared memory segment is being used. Andres Freund, with modifications by me, reviewed (several years ago) by Michael Paquier, Marti Raudsepp, and Tom Lane. Discussion: http://postgr.es/m/20140504114417.GM12715@awork2.anarazel.de --- doc/src/sgml/catalogs.sgml | 64 +++++++++++++++ doc/src/sgml/xfunc.sgml | 2 +- src/backend/catalog/system_views.sql | 6 ++ src/backend/storage/ipc/shmem.c | 113 +++++++++++++++++++++++++++ src/include/catalog/pg_proc.dat | 9 +++ src/test/regress/expected/rules.out | 4 + 6 files changed, 197 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 55694c4368..070ea0e93a 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -10748,6 +10748,70 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx + + <structname>pg_shmem_allocations</structname> + + + pg_shmem_allocations + + + + The pg_shmem_allocations view shows allocations + made from the server's main shared memory segment. This includes both + memory allocated by postgres itself and memory + allocated by extensions using the mechanisms detailed in + . + + + + Note that this view does not include memory allocated using the dynamic + shared memory infrastructure. + + + + <structname>pg_shmem_allocations</structname> Columns + + + + + Name + Type + Description + + + + + + name + text + The name of the shared memory allocation. NULL for unused memory + and <anonymous> for anonymous allocations. + + + + off + bigint + The offset at which the allocation starts. NULL for anonymous + allocations. + + + + size + bigint + Size of the allocation + + + +
+ + + Anonymous allocations are allocations that have been made + with ShmemAlloc() directly, rather than via + ShmemInitStruct() or + ShmemInitHash() or. + + + <structname>pg_stats</structname> diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml index d9afd3be4d..bb8468553c 100644 --- a/doc/src/sgml/xfunc.sgml +++ b/doc/src/sgml/xfunc.sgml @@ -3241,7 +3241,7 @@ CREATE FUNCTION make_array(anyelement) RETURNS anyarray - + Shared Memory and LWLocks diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql index 4456fefb38..cfa3b752c7 100644 --- a/src/backend/catalog/system_views.sql +++ b/src/backend/catalog/system_views.sql @@ -547,6 +547,12 @@ CREATE VIEW pg_config AS REVOKE ALL on pg_config FROM PUBLIC; REVOKE EXECUTE ON FUNCTION pg_config() FROM PUBLIC; +CREATE VIEW pg_shmem_allocations AS + SELECT * FROM pg_get_shmem_allocations(); + +REVOKE ALL ON pg_shmem_allocations FROM PUBLIC; +REVOKE EXECUTE ON FUNCTION pg_get_shmem_allocations() FROM PUBLIC; + -- Statistics views CREATE VIEW pg_stat_all_tables AS diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c index a1567d3559..57d6bf1c7b 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -66,11 +66,14 @@ #include "postgres.h" #include "access/transam.h" +#include "fmgr.h" +#include "funcapi.h" #include "miscadmin.h" #include "storage/lwlock.h" #include "storage/pg_shmem.h" #include "storage/shmem.h" #include "storage/spin.h" +#include "utils/builtins.h" /* shared memory global variables */ @@ -503,3 +506,113 @@ mul_size(Size s1, Size s2) errmsg("requested shared memory size overflows size_t"))); return result; } + +/* SQL SRF showing allocated shared memory */ +Datum +pg_get_shmem_allocations(PG_FUNCTION_ARGS) +{ +#define PG_GET_SHMEM_SIZES_COLS 3 + ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo; + TupleDesc tupdesc; + Tuplestorestate *tupstore; + MemoryContext per_query_ctx; + MemoryContext oldcontext; + HASH_SEQ_STATUS hstat; + ShmemIndexEnt *ent; + Size named_allocated = 0; + + /* check to see if caller supports us returning a tuplestore */ + if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("set-valued function called in context that cannot accept a set"))); + if (!(rsinfo->allowedModes & SFRM_Materialize)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("materialize mode required, but it is not " \ + "allowed in this context"))); + + /* Build a tuple descriptor for our result type */ + if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) + elog(ERROR, "return type must be a row type"); + + per_query_ctx = rsinfo->econtext->ecxt_per_query_memory; + oldcontext = MemoryContextSwitchTo(per_query_ctx); + + tupstore = tuplestore_begin_heap(true, false, work_mem); + rsinfo->returnMode = SFRM_Materialize; + rsinfo->setResult = tupstore; + rsinfo->setDesc = tupdesc; + + MemoryContextSwitchTo(oldcontext); + + LWLockAcquire(ShmemIndexLock, LW_SHARED); + + hash_seq_init(&hstat, ShmemIndex); + + /* output all allocated entries */ + while ((ent = (ShmemIndexEnt *) hash_seq_search(&hstat)) != NULL) + { + Datum values[PG_GET_SHMEM_SIZES_COLS]; + bool nulls[PG_GET_SHMEM_SIZES_COLS]; + + /* key */ + values[0] = CStringGetTextDatum(ent->key); + nulls[0] = false; + + /* off */ + values[1] = Int64GetDatum((char *) ent->location - (char *) ShmemSegHdr); + nulls[1] = false; + + /* size */ + values[2] = Int64GetDatum(ent->size); + nulls[2] = false; + named_allocated += ent->size; + + tuplestore_putvalues(tupstore, tupdesc, values, nulls); + } + + /* output shared memory allocated but not counted via the shmem index */ + { + Datum values[PG_GET_SHMEM_SIZES_COLS]; + bool nulls[PG_GET_SHMEM_SIZES_COLS]; + + /* key */ + values[0] = CStringGetTextDatum(""); + nulls[0] = false; + + /* off */ + nulls[1] = true; + + /* size */ + values[2] = Int64GetDatum(ShmemSegHdr->freeoffset - named_allocated); + nulls[2] = false; + + tuplestore_putvalues(tupstore, tupdesc, values, nulls); + } + + /* output as-of-yet unused shared memory */ + { + Datum values[PG_GET_SHMEM_SIZES_COLS]; + bool nulls[PG_GET_SHMEM_SIZES_COLS]; + + /* key, show unallocated as NULL */ + nulls[0] = true; + + /* off */ + values[1] = Int64GetDatum(ShmemSegHdr->freeoffset); + nulls[1] = false; + + /* size */ + values[2] = Int64GetDatum(ShmemSegHdr->totalsize - ShmemSegHdr->freeoffset); + nulls[2] = false; + + tuplestore_putvalues(tupstore, tupdesc, values, nulls); + } + + LWLockRelease(ShmemIndexLock); + + tuplestore_donestoring(tupstore); + + return (Datum) 0; +} diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 58ea5b982b..29f093b87a 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -7656,6 +7656,15 @@ prorettype => 'float8', proargtypes => '', prosrc => 'pg_notification_queue_usage' }, +# shared memory usage +{ oid => '8613', + descr => 'allocations from the main shared memory segment', + proname => 'pg_get_shmem_allocations', 'prorows' => 10, 'proretset' => 't', + provolatile => 's', 'prorettype' => 'record', 'proargtypes' => '', + proallargtypes => '{text,int8,int8}', proargmodes => '{o,o,o}', + proargnames => '{name,off,size}', + prosrc => 'pg_get_shmem_allocations' }, + # non-persistent series generator { oid => '1066', descr => 'non-persistent series generator', proname => 'generate_series', prorows => '1000', diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 14e7214346..4c1bb88c8d 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -1721,6 +1721,10 @@ pg_shadow| SELECT pg_authid.rolname AS usename, FROM (pg_authid LEFT JOIN pg_db_role_setting s ON (((pg_authid.oid = s.setrole) AND (s.setdatabase = (0)::oid)))) WHERE pg_authid.rolcanlogin; +pg_shmem_allocations| SELECT pg_get_shmem_allocations.name, + pg_get_shmem_allocations.off, + pg_get_shmem_allocations.size + FROM pg_get_shmem_allocations() pg_get_shmem_allocations(name, off, size); pg_stat_activity| SELECT s.datid, d.datname, s.pid, -- 2.17.2 (Apple Git-113)