From ed10f32e37e9a16814c25e400d7826745ae3c797 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Thu, 9 Jan 2020 10:59:07 -0500 Subject: [PATCH] Add pg_shmem_allocations view. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This tells you about allocations that have been made from the main shared memory segment. The original patch also tried to show information about dynamic shared memory allocation as well, but I decided to leave that problem for another time. Andres Freund and Robert Haas, reviewed by Michael Paquier, Marti Raudsepp, Tom Lane, Álvaro Herrera, and Kyotaro Horiguchi. Discussion: http://postgr.es/m/20140504114417.GM12715@awork2.anarazel.de --- doc/src/sgml/catalogs.sgml | 85 +++++++++++++++++++++ doc/src/sgml/xfunc.sgml | 2 +- src/backend/catalog/system_views.sql | 6 ++ src/backend/storage/ipc/shmem.c | 106 ++++++++++++++++++++++++++- src/include/catalog/pg_proc.dat | 9 +++ src/include/storage/shmem.h | 3 +- src/test/regress/expected/rules.out | 5 ++ 7 files changed, 212 insertions(+), 4 deletions(-) diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 55694c4368..85ac79f07e 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -8362,6 +8362,11 @@ SCRAM-SHA-256$<iteration count>:&l planner statistics + + pg_shmem_allocations + shared memory allocations + + pg_stats_ext extended planner statistics @@ -10748,6 +10753,86 @@ 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 and unused memory. + + + + size + bigint + Size of the allocation + + + + allocated_size + bigint + Size of the allocation including padding. For anonymous + allocations, no information about padding is available, so the + size and allocated_size columns + will always be equal. Padding is not meaningful for free memory, so + the columns will be equal in that case also. + + + +
+ + + Anonymous allocations are allocations that have been made + with ShmemAlloc() directly, rather than via + ShmemInitStruct() or + ShmemInitHash(). + + + + By default, the pg_shmem_allocations view can be + read only by superusers. + + + <structname>pg_stats</structname> diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml index 5616524cfd..ca5e6efd7e 100644 --- a/doc/src/sgml/xfunc.sgml +++ b/doc/src/sgml/xfunc.sgml @@ -3239,7 +3239,7 @@ 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 2fc3e3ff90..773edf85e7 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 a4f0ec1a67..2892a573e4 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -66,12 +66,16 @@ #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" +static void *ShmemAllocRaw(Size size, Size *allocated_size); /* shared memory global variables */ @@ -157,8 +161,9 @@ void * ShmemAlloc(Size size) { void *newSpace; + Size allocated_size; - newSpace = ShmemAllocNoError(size); + newSpace = ShmemAllocRaw(size, &allocated_size); if (!newSpace) ereport(ERROR, (errcode(ERRCODE_OUT_OF_MEMORY), @@ -174,6 +179,20 @@ ShmemAlloc(Size size) */ void * ShmemAllocNoError(Size size) +{ + Size allocated_size; + + return ShmemAllocRaw(size, &allocated_size); +} + +/* + * ShmemAllocRaw -- allocate align chunk and return allocated size + * + * Also sets *allocated_size to the number of bytes allocated, which will + * be equal to the number requested plus any padding we choose to add. + */ +static void * +ShmemAllocRaw(Size size, Size *allocated_size) { Size newStart; Size newFree; @@ -191,6 +210,7 @@ ShmemAllocNoError(Size size) * won't be sufficient. */ size = CACHELINEALIGN(size); + *allocated_size = size; Assert(ShmemSegHdr != NULL); @@ -441,8 +461,10 @@ ShmemInitStruct(const char *name, Size size, bool *foundPtr) } else { + Size allocated_size; + /* It isn't in the table yet. allocate and initialize it */ - structPtr = ShmemAllocNoError(size); + structPtr = ShmemAllocRaw(size, &allocated_size); if (structPtr == NULL) { /* out of memory; remove the failed ShmemIndex entry */ @@ -455,6 +477,7 @@ ShmemInitStruct(const char *name, Size size, bool *foundPtr) name, size))); } result->size = size; + result->allocated_size = allocated_size; result->location = structPtr; } @@ -503,3 +526,82 @@ 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 4 + 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; + Datum values[PG_GET_SHMEM_SIZES_COLS]; + bool nulls[PG_GET_SHMEM_SIZES_COLS]; + + /* 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 */ + memset(nulls, 0, sizeof(nulls)); + while ((ent = (ShmemIndexEnt *) hash_seq_search(&hstat)) != NULL) + { + values[0] = CStringGetTextDatum(ent->key); + values[1] = Int64GetDatum((char *) ent->location - (char *) ShmemSegHdr); + values[2] = Int64GetDatum(ent->size); + values[3] = Int64GetDatum(ent->allocated_size); + named_allocated += ent->allocated_size; + + tuplestore_putvalues(tupstore, tupdesc, values, nulls); + } + + /* output shared memory allocated but not counted via the shmem index */ + values[0] = CStringGetTextDatum(""); + nulls[1] = true; + values[2] = Int64GetDatum(ShmemSegHdr->freeoffset - named_allocated); + values[3] = values[2]; + tuplestore_putvalues(tupstore, tupdesc, values, nulls); + + /* output as-of-yet unused shared memory */ + nulls[0] = true; + values[1] = Int64GetDatum(ShmemSegHdr->freeoffset); + nulls[1] = false; + values[2] = Int64GetDatum(ShmemSegHdr->totalsize - ShmemSegHdr->freeoffset); + values[3] = values[2]; + 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 59f1ff01ab..427faa3c3b 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -7663,6 +7663,15 @@ proparallel => 'r', 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' => 50, 'proretset' => 't', + provolatile => 'v', 'prorettype' => 'record', 'proargtypes' => '', + proallargtypes => '{text,int8,int8,int8}', proargmodes => '{o,o,o,o}', + proargnames => '{name,off,size,allocated_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/include/storage/shmem.h b/src/include/storage/shmem.h index 243b73f8bb..0c1af89206 100644 --- a/src/include/storage/shmem.h +++ b/src/include/storage/shmem.h @@ -59,7 +59,8 @@ typedef struct { char key[SHMEM_INDEX_KEYSIZE]; /* string name */ void *location; /* location in shared mem */ - Size size; /* # bytes allocated for the structure */ + Size size; /* # bytes requested for the structure */ + Size allocated_size; /* # bytes actually allocated */ } ShmemIndexEnt; /* diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 80a07825b9..62eaf90a0f 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -1721,6 +1721,11 @@ 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, + pg_get_shmem_allocations.allocated_size + FROM pg_get_shmem_allocations() pg_get_shmem_allocations(name, off, size, allocated_size); pg_stat_activity| SELECT s.datid, d.datname, s.pid,