PostgreSQL Source Code git master
All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Pages
ipci.c
Go to the documentation of this file.
1/*-------------------------------------------------------------------------
2 *
3 * ipci.c
4 * POSTGRES inter-process communication initialization code.
5 *
6 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/storage/ipc/ipci.c
12 *
13 *-------------------------------------------------------------------------
14 */
15#include "postgres.h"
16
17#include "access/clog.h"
18#include "access/commit_ts.h"
19#include "access/multixact.h"
20#include "access/nbtree.h"
21#include "access/subtrans.h"
22#include "access/syncscan.h"
23#include "access/transam.h"
24#include "access/twophase.h"
26#include "access/xlogrecovery.h"
27#include "commands/async.h"
28#include "miscadmin.h"
29#include "pgstat.h"
32#include "postmaster/bgwriter.h"
35#include "replication/origin.h"
36#include "replication/slot.h"
40#include "storage/bufmgr.h"
41#include "storage/dsm.h"
43#include "storage/ipc.h"
44#include "storage/pg_shmem.h"
45#include "storage/pmsignal.h"
46#include "storage/predicate.h"
47#include "storage/proc.h"
48#include "storage/procarray.h"
49#include "storage/procsignal.h"
50#include "storage/sinvaladt.h"
51#include "utils/guc.h"
53
54/* GUCs */
56
58
60
61static void CreateOrAttachShmemStructs(void);
62
63/*
64 * RequestAddinShmemSpace
65 * Request that extra shmem space be allocated for use by
66 * a loadable module.
67 *
68 * This may only be called via the shmem_request_hook of a library that is
69 * loaded into the postmaster via shared_preload_libraries. Calls from
70 * elsewhere will fail.
71 */
72void
74{
76 elog(FATAL, "cannot request additional shared memory outside shmem_request_hook");
78}
79
80/*
81 * CalculateShmemSize
82 * Calculates the amount of shared memory and number of semaphores needed.
83 *
84 * If num_semaphores is not NULL, it will be set to the number of semaphores
85 * required.
86 */
87Size
88CalculateShmemSize(int *num_semaphores)
89{
90 Size size;
91 int numSemas;
92
93 /* Compute number of semaphores we'll need */
94 numSemas = ProcGlobalSemas();
95
96 /* Return the number of semaphores if requested by the caller */
97 if (num_semaphores)
98 *num_semaphores = numSemas;
99
100 /*
101 * Size of the Postgres shared-memory block is estimated via moderately-
102 * accurate estimates for the big hogs, plus 100K for the stuff that's too
103 * small to bother with estimating.
104 *
105 * We take some care to ensure that the total size request doesn't
106 * overflow size_t. If this gets through, we don't need to be so careful
107 * during the actual allocation phase.
108 */
109 size = 100000;
112 sizeof(ShmemIndexEnt)));
151
152 /* include additional requested shmem from preload libraries */
154
155 /* might as well round it off to a multiple of a typical page size */
156 size = add_size(size, 8192 - (size % 8192));
157
158 return size;
159}
160
161#ifdef EXEC_BACKEND
162/*
163 * AttachSharedMemoryStructs
164 * Initialize a postmaster child process's access to shared memory
165 * structures.
166 *
167 * In !EXEC_BACKEND mode, we inherit everything through the fork, and this
168 * isn't needed.
169 */
170void
171AttachSharedMemoryStructs(void)
172{
173 /* InitProcess must've been called already */
174 Assert(MyProc != NULL);
176
177 /*
178 * In EXEC_BACKEND mode, backends don't inherit the number of fast-path
179 * groups we calculated before setting the shmem up, so recalculate it.
180 */
182
184
185 /*
186 * Now give loadable modules a chance to set up their shmem allocations
187 */
190}
191#endif
192
193/*
194 * CreateSharedMemoryAndSemaphores
195 * Creates and initializes shared memory and semaphores.
196 */
197void
199{
200 PGShmemHeader *shim;
201 PGShmemHeader *seghdr;
202 Size size;
203 int numSemas;
204
206
207 /* Compute the size of the shared-memory block */
208 size = CalculateShmemSize(&numSemas);
209 elog(DEBUG3, "invoking IpcMemoryCreate(size=%zu)", size);
210
211 /*
212 * Create the shmem segment
213 */
214 seghdr = PGSharedMemoryCreate(size, &shim);
215
216 /*
217 * Make sure that huge pages are never reported as "unknown" while the
218 * server is running.
219 */
220 Assert(strcmp("unknown",
221 GetConfigOption("huge_pages_status", false, false)) != 0);
222
223 InitShmemAccess(seghdr);
224
225 /*
226 * Create semaphores
227 */
228 PGReserveSemaphores(numSemas);
229
230 /*
231 * Set up shared memory allocation mechanism
232 */
234
235 /* Initialize subsystems */
237
238 /* Initialize dynamic shared memory facilities. */
240
241 /*
242 * Now give loadable modules a chance to set up their shmem allocations
243 */
246}
247
248/*
249 * Initialize various subsystems, setting up their data structures in
250 * shared memory.
251 *
252 * This is called by the postmaster or by a standalone backend.
253 * It is also called by a backend forked from the postmaster in the
254 * EXEC_BACKEND case. In the latter case, the shared memory segment
255 * already exists and has been physically attached to, but we have to
256 * initialize pointers in local memory that reference the shared structures,
257 * because we didn't inherit the correct pointer values from the postmaster
258 * as we do in the fork() scenario. The easiest way to do that is to run
259 * through the same code as before. (Note that the called routines mostly
260 * check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case.
261 * This is a bit code-wasteful and could be cleaned up.)
262 */
263static void
265{
266 /*
267 * Now initialize LWLocks, which do shared memory allocation and are
268 * needed for InitShmemIndex.
269 */
271
272 /*
273 * Set up shmem.c index hashtable
274 */
276
279
280 /*
281 * Set up xlog, clog, and buffers
282 */
292
293 /*
294 * Set up lock manager
295 */
297
298 /*
299 * Set up predicate lock manager
300 */
302
303 /*
304 * Set up process table
305 */
312
313 /*
314 * Set up shared-inval messaging
315 */
317
318 /*
319 * Set up interprocess signaling mechanisms
320 */
333
334 /*
335 * Set up other modules that need some shared memory space
336 */
343}
344
345/*
346 * InitializeShmemGUCs
347 *
348 * This function initializes runtime-computed GUCs related to the amount of
349 * shared memory required for the current configuration.
350 */
351void
353{
354 char buf[64];
355 Size size_b;
356 Size size_mb;
357 Size hp_size;
358 int num_semas;
359
360 /*
361 * Calculate the shared memory size and round up to the nearest megabyte.
362 */
363 size_b = CalculateShmemSize(&num_semas);
364 size_mb = add_size(size_b, (1024 * 1024) - 1) / (1024 * 1024);
365 sprintf(buf, "%zu", size_mb);
366 SetConfigOption("shared_memory_size", buf,
368
369 /*
370 * Calculate the number of huge pages required.
371 */
372 GetHugePageSize(&hp_size, NULL);
373 if (hp_size != 0)
374 {
375 Size hp_required;
376
377 hp_required = add_size(size_b / hp_size, 1);
378 sprintf(buf, "%zu", hp_required);
379 SetConfigOption("shared_memory_size_in_huge_pages", buf,
381 }
382
383 sprintf(buf, "%d", num_semas);
385}
Size AsyncShmemSize(void)
Definition: async.c:485
void AsyncShmemInit(void)
Definition: async.c:502
Size AutoVacuumShmemSize(void)
Definition: autovacuum.c:3262
void AutoVacuumShmemInit(void)
Definition: autovacuum.c:3281
void BackendStatusShmemInit(void)
Size BackendStatusShmemSize(void)
void BackgroundWorkerShmemInit(void)
Definition: bgworker.c:162
Size BackgroundWorkerShmemSize(void)
Definition: bgworker.c:146
Size BufferManagerShmemSize(void)
Definition: buf_init.c:159
void BufferManagerShmemInit(void)
Definition: buf_init.c:67
#define Assert(condition)
Definition: c.h:812
size_t Size
Definition: c.h:559
void CheckpointerShmemInit(void)
Definition: checkpointer.c:909
Size CheckpointerShmemSize(void)
Definition: checkpointer.c:890
void CLOGShmemInit(void)
Definition: clog.c:787
Size CLOGShmemSize(void)
Definition: clog.c:781
Size CommitTsShmemSize(void)
Definition: commit_ts.c:519
void CommitTsShmemInit(void)
Definition: commit_ts.c:530
size_t dsm_estimate_size(void)
Definition: dsm.c:470
void dsm_postmaster_startup(PGShmemHeader *shim)
Definition: dsm.c:177
void dsm_shmem_init(void)
Definition: dsm.c:479
void DSMRegistryShmemInit(void)
Definition: dsm_registry.c:69
Size DSMRegistryShmemSize(void)
Definition: dsm_registry.c:63
Size hash_estimate_size(long num_entries, Size entrysize)
Definition: dynahash.c:783
#define DEBUG3
Definition: elog.h:28
#define FATAL
Definition: elog.h:41
#define elog(elevel,...)
Definition: elog.h:225
bool IsUnderPostmaster
Definition: globals.c:119
void SetConfigOption(const char *name, const char *value, GucContext context, GucSource source)
Definition: guc.c:4332
const char * GetConfigOption(const char *name, bool missing_ok, bool restrict_privileged)
Definition: guc.c:4355
@ PGC_S_DYNAMIC_DEFAULT
Definition: guc.h:110
@ PGC_INTERNAL
Definition: guc.h:69
void InjectionPointShmemInit(void)
Size InjectionPointShmemSize(void)
void(* shmem_startup_hook_type)(void)
Definition: ipc.h:22
static Size total_addin_request
Definition: ipci.c:59
int shared_memory_type
Definition: ipci.c:55
shmem_startup_hook_type shmem_startup_hook
Definition: ipci.c:57
void RequestAddinShmemSpace(Size size)
Definition: ipci.c:73
Size CalculateShmemSize(int *num_semaphores)
Definition: ipci.c:88
void InitializeShmemGUCs(void)
Definition: ipci.c:352
static void CreateOrAttachShmemStructs(void)
Definition: ipci.c:264
void CreateSharedMemoryAndSemaphores(void)
Definition: ipci.c:198
Size ApplyLauncherShmemSize(void)
Definition: launcher.c:896
void ApplyLauncherShmemInit(void)
Definition: launcher.c:951
Size LockManagerShmemSize(void)
Definition: lock.c:3663
void LockManagerShmemInit(void)
Definition: lock.c:438
void CreateLWLocks(void)
Definition: lwlock.c:450
Size LWLockShmemSize(void)
Definition: lwlock.c:420
bool process_shmem_requests_in_progress
Definition: miscinit.c:1838
void MultiXactShmemInit(void)
Definition: multixact.c:1964
Size MultiXactShmemSize(void)
Definition: multixact.c:1947
void BTreeShmemInit(void)
Definition: nbtutils.c:4539
Size BTreeShmemSize(void)
Definition: nbtutils.c:4526
Size ReplicationOriginShmemSize(void)
Definition: origin.c:510
void ReplicationOriginShmemInit(void)
Definition: origin.c:530
#define DEFAULT_SHARED_MEMORY_TYPE
Definition: pg_shmem.h:75
static char * buf
Definition: pg_test_fsync.c:72
Size PgArchShmemSize(void)
Definition: pgarch.c:155
void PgArchShmemInit(void)
Definition: pgarch.c:166
void StatsShmemInit(void)
Definition: pgstat_shmem.c:156
Size StatsShmemSize(void)
Definition: pgstat_shmem.c:127
Size PMSignalShmemSize(void)
Definition: pmsignal.c:130
void PMSignalShmemInit(void)
Definition: pmsignal.c:145
#define sprintf
Definition: port.h:240
Size PGSemaphoreShmemSize(int maxSemas)
Definition: posix_sema.c:165
void PGReserveSemaphores(int maxSemas)
Definition: posix_sema.c:196
void InitializeFastPathLocks(void)
Definition: postinit.c:577
void PredicateLockShmemInit(void)
Definition: predicate.c:1145
Size PredicateLockShmemSize(void)
Definition: predicate.c:1347
Size ProcArrayShmemSize(void)
Definition: procarray.c:376
void ProcArrayShmemInit(void)
Definition: procarray.c:418
void ProcSignalShmemInit(void)
Definition: procsignal.c:130
Size ProcSignalShmemSize(void)
Definition: procsignal.c:116
void InitShmemIndex(void)
Definition: shmem.c:278
void InitShmemAccess(PGShmemHeader *seghdr)
Definition: shmem.c:97
Size add_size(Size s1, Size s2)
Definition: shmem.c:488
void InitShmemAllocation(void)
Definition: shmem.c:110
#define SHMEM_INDEX_SIZE
Definition: shmem.h:51
Size SharedInvalShmemSize(void)
Definition: sinvaladt.c:217
void SharedInvalShmemInit(void)
Definition: sinvaladt.c:233
static pg_noinline void Size size
Definition: slab.c:607
void ReplicationSlotsShmemInit(void)
Definition: slot.c:189
Size ReplicationSlotsShmemSize(void)
Definition: slot.c:171
void SlotSyncShmemInit(void)
Definition: slotsync.c:1667
Size SlotSyncShmemSize(void)
Definition: slotsync.c:1658
PGPROC * MyProc
Definition: proc.c:66
Size ProcGlobalShmemSize(void)
Definition: proc.c:97
int ProcGlobalSemas(void)
Definition: proc.c:130
void InitProcGlobal(void)
Definition: proc.c:165
void SUBTRANSShmemInit(void)
Definition: subtrans.c:220
Size SUBTRANSShmemSize(void)
Definition: subtrans.c:214
void SyncScanShmemInit(void)
Definition: syncscan.c:135
Size SyncScanShmemSize(void)
Definition: syncscan.c:126
PGShmemHeader * PGSharedMemoryCreate(Size size, PGShmemHeader **shim)
Definition: sysv_shmem.c:700
void GetHugePageSize(Size *hugepagesize, int *mmap_flags)
Definition: sysv_shmem.c:479
Size TwoPhaseShmemSize(void)
Definition: twophase.c:237
void TwoPhaseShmemInit(void)
Definition: twophase.c:253
Size VarsupShmemSize(void)
Definition: varsup.c:41
void VarsupShmemInit(void)
Definition: varsup.c:47
Size WaitEventCustomShmemSize(void)
Definition: wait_event.c:103
void WaitEventCustomShmemInit(void)
Definition: wait_event.c:119
void WalRcvShmemInit(void)
Size WalRcvShmemSize(void)
void WalSndShmemInit(void)
Definition: walsender.c:3594
Size WalSndShmemSize(void)
Definition: walsender.c:3582
Size WalSummarizerShmemSize(void)
void WalSummarizerShmemInit(void)
void XLOGShmemInit(void)
Definition: xlog.c:4918
Size XLOGShmemSize(void)
Definition: xlog.c:4868
size_t XLogPrefetchShmemSize(void)
void XLogPrefetchShmemInit(void)
Size XLogRecoveryShmemSize(void)
Definition: xlogrecovery.c:447
void XLogRecoveryShmemInit(void)
Definition: xlogrecovery.c:458