PostgreSQL Source Code  git master
bgworker.c File Reference
#include "postgres.h"
#include "access/parallel.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "port/atomics.h"
#include "postmaster/bgworker_internals.h"
#include "postmaster/interrupt.h"
#include "postmaster/postmaster.h"
#include "replication/logicallauncher.h"
#include "replication/logicalworker.h"
#include "storage/dsm.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lwlock.h"
#include "storage/pg_shmem.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/procsignal.h"
#include "storage/shmem.h"
#include "tcop/tcopprot.h"
#include "utils/ascii.h"
#include "utils/ps_status.h"
#include "utils/timeout.h"
Include dependency graph for bgworker.c:

Go to the source code of this file.

Data Structures

struct  BackgroundWorkerSlot
 
struct  BackgroundWorkerArray
 
struct  BackgroundWorkerHandle
 

Typedefs

typedef struct BackgroundWorkerSlot BackgroundWorkerSlot
 
typedef struct BackgroundWorkerArray BackgroundWorkerArray
 

Functions

static bgworker_main_type LookupBackgroundWorkerFunction (const char *libraryname, const char *funcname)
 
Size BackgroundWorkerShmemSize (void)
 
void BackgroundWorkerShmemInit (void)
 
static RegisteredBgWorkerFindRegisteredWorkerBySlotNumber (int slotno)
 
void BackgroundWorkerStateChange (bool allow_new_workers)
 
void ForgetBackgroundWorker (slist_mutable_iter *cur)
 
void ReportBackgroundWorkerPID (RegisteredBgWorker *rw)
 
void ReportBackgroundWorkerExit (slist_mutable_iter *cur)
 
void BackgroundWorkerStopNotifications (pid_t pid)
 
void ForgetUnstartedBackgroundWorkers (void)
 
void ResetBackgroundWorkerCrashTimes (void)
 
static bool SanityCheckBackgroundWorker (BackgroundWorker *worker, int elevel)
 
static void bgworker_die (SIGNAL_ARGS)
 
void StartBackgroundWorker (void)
 
void RegisterBackgroundWorker (BackgroundWorker *worker)
 
bool RegisterDynamicBackgroundWorker (BackgroundWorker *worker, BackgroundWorkerHandle **handle)
 
BgwHandleStatus GetBackgroundWorkerPid (BackgroundWorkerHandle *handle, pid_t *pidp)
 
BgwHandleStatus WaitForBackgroundWorkerStartup (BackgroundWorkerHandle *handle, pid_t *pidp)
 
BgwHandleStatus WaitForBackgroundWorkerShutdown (BackgroundWorkerHandle *handle)
 
void TerminateBackgroundWorker (BackgroundWorkerHandle *handle)
 
const char * GetBackgroundWorkerTypeByPid (pid_t pid)
 

Variables

slist_head BackgroundWorkerList = SLIST_STATIC_INIT(BackgroundWorkerList)
 
static BackgroundWorkerArrayBackgroundWorkerData
 
struct {
   const char *   fn_name
 
   bgworker_main_type   fn_addr
 
InternalBGWorkers []
 

Typedef Documentation

◆ BackgroundWorkerArray

◆ BackgroundWorkerSlot

Function Documentation

◆ BackgroundWorkerShmemInit()

void BackgroundWorkerShmemInit ( void  )

Definition at line 158 of file bgworker.c.

References Assert, BackgroundWorkerShmemSize(), BackgroundWorker::bgw_notify_pid, slist_iter::cur, BackgroundWorkerSlot::generation, BackgroundWorkerSlot::in_use, InvalidPid, IsUnderPostmaster, max_worker_processes, BackgroundWorkerArray::parallel_register_count, BackgroundWorkerArray::parallel_terminate_count, BackgroundWorkerSlot::pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_worker, ShmemInitStruct(), slist_container, slist_foreach, BackgroundWorkerArray::slot, BackgroundWorkerSlot::terminate, BackgroundWorkerArray::total_slots, and BackgroundWorkerSlot::worker.

Referenced by CreateSharedMemoryAndSemaphores().

159 {
160  bool found;
161 
162  BackgroundWorkerData = ShmemInitStruct("Background Worker Data",
164  &found);
165  if (!IsUnderPostmaster)
166  {
167  slist_iter siter;
168  int slotno = 0;
169 
173 
174  /*
175  * Copy contents of worker list into shared memory. Record the shared
176  * memory slot assigned to each worker. This ensures a 1-to-1
177  * correspondence between the postmaster's private list and the array
178  * in shared memory.
179  */
181  {
183  RegisteredBgWorker *rw;
184 
185  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
186  Assert(slotno < max_worker_processes);
187  slot->in_use = true;
188  slot->terminate = false;
189  slot->pid = InvalidPid;
190  slot->generation = 0;
191  rw->rw_shmem_slot = slotno;
192  rw->rw_worker.bgw_notify_pid = 0; /* might be reinit after crash */
193  memcpy(&slot->worker, &rw->rw_worker, sizeof(BackgroundWorker));
194  ++slotno;
195  }
196 
197  /*
198  * Mark any remaining slots as not in use.
199  */
200  while (slotno < max_worker_processes)
201  {
203 
204  slot->in_use = false;
205  ++slotno;
206  }
207  }
208  else
209  Assert(found);
210 }
slist_node * cur
Definition: ilist.h:226
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
Size BackgroundWorkerShmemSize(void)
Definition: bgworker.c:142
void * ShmemInitStruct(const char *name, Size size, bool *foundPtr)
Definition: shmem.c:396
slist_head BackgroundWorkerList
Definition: bgworker.c:42
uint32 parallel_register_count
Definition: bgworker.c:99
bool IsUnderPostmaster
Definition: globals.c:112
#define slist_container(type, membername, ptr)
Definition: ilist.h:693
#define Assert(condition)
Definition: c.h:804
BackgroundWorker worker
Definition: bgworker.c:82
#define slist_foreach(iter, lhead)
Definition: ilist.h:719
uint32 parallel_terminate_count
Definition: bgworker.c:100
pid_t bgw_notify_pid
Definition: bgworker.h:99
int max_worker_processes
Definition: globals.c:137
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101
#define InvalidPid
Definition: miscadmin.h:32

◆ BackgroundWorkerShmemSize()

Size BackgroundWorkerShmemSize ( void  )

Definition at line 142 of file bgworker.c.

References add_size(), max_worker_processes, mul_size(), and offsetof.

Referenced by BackgroundWorkerShmemInit(), and CreateSharedMemoryAndSemaphores().

143 {
144  Size size;
145 
146  /* Array of workers is variably sized. */
147  size = offsetof(BackgroundWorkerArray, slot);
149  sizeof(BackgroundWorkerSlot)));
150 
151  return size;
152 }
Size mul_size(Size s1, Size s2)
Definition: shmem.c:519
Size add_size(Size s1, Size s2)
Definition: shmem.c:502
size_t Size
Definition: c.h:540
int max_worker_processes
Definition: globals.c:137
#define offsetof(type, field)
Definition: c.h:727

◆ BackgroundWorkerStateChange()

void BackgroundWorkerStateChange ( bool  allow_new_workers)

Definition at line 242 of file bgworker.c.

References ascii_safe_strlcpy(), BackgroundWorker::bgw_extra, BGW_EXTRALEN, BackgroundWorker::bgw_flags, BackgroundWorker::bgw_function_name, BackgroundWorker::bgw_library_name, BackgroundWorker::bgw_main_arg, BGW_MAXLEN, BackgroundWorker::bgw_name, BackgroundWorker::bgw_notify_pid, BackgroundWorker::bgw_restart_time, BackgroundWorker::bgw_start_time, BackgroundWorker::bgw_type, BGWORKER_CLASS_PARALLEL, DEBUG1, elog, ereport, errcode(), errmsg(), errmsg_internal(), FindRegisteredWorkerBySlotNumber(), BackgroundWorkerSlot::in_use, kill, LOG, malloc, max_worker_processes, BackgroundWorkerArray::parallel_terminate_count, pg_memory_barrier, pg_read_barrier, BackgroundWorkerSlot::pid, PostmasterMarkPIDForWorkerNotify(), ReportBackgroundWorkerPID(), RegisteredBgWorker::rw_backend, RegisteredBgWorker::rw_child_slot, RegisteredBgWorker::rw_crashed_at, RegisteredBgWorker::rw_lnode, RegisteredBgWorker::rw_pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_terminate, RegisteredBgWorker::rw_worker, SIGUSR1, slist_push_head(), BackgroundWorkerArray::slot, BackgroundWorkerSlot::terminate, BackgroundWorkerArray::total_slots, and BackgroundWorkerSlot::worker.

Referenced by sigusr1_handler().

243 {
244  int slotno;
245 
246  /*
247  * The total number of slots stored in shared memory should match our
248  * notion of max_worker_processes. If it does not, something is very
249  * wrong. Further down, we always refer to this value as
250  * max_worker_processes, in case shared memory gets corrupted while we're
251  * looping.
252  */
254  {
255  ereport(LOG,
256  (errmsg("inconsistent background worker state (max_worker_processes=%d, total_slots=%d)",
259  return;
260  }
261 
262  /*
263  * Iterate through slots, looking for newly-registered workers or workers
264  * who must die.
265  */
266  for (slotno = 0; slotno < max_worker_processes; ++slotno)
267  {
269  RegisteredBgWorker *rw;
270 
271  if (!slot->in_use)
272  continue;
273 
274  /*
275  * Make sure we don't see the in_use flag before the updated slot
276  * contents.
277  */
278  pg_read_barrier();
279 
280  /* See whether we already know about this worker. */
282  if (rw != NULL)
283  {
284  /*
285  * In general, the worker data can't change after it's initially
286  * registered. However, someone can set the terminate flag.
287  */
288  if (slot->terminate && !rw->rw_terminate)
289  {
290  rw->rw_terminate = true;
291  if (rw->rw_pid != 0)
292  kill(rw->rw_pid, SIGTERM);
293  else
294  {
295  /* Report never-started, now-terminated worker as dead. */
297  }
298  }
299  continue;
300  }
301 
302  /*
303  * If we aren't allowing new workers, then immediately mark it for
304  * termination; the next stanza will take care of cleaning it up.
305  * Doing this ensures that any process waiting for the worker will get
306  * awoken, even though the worker will never be allowed to run.
307  */
308  if (!allow_new_workers)
309  slot->terminate = true;
310 
311  /*
312  * If the worker is marked for termination, we don't need to add it to
313  * the registered workers list; we can just free the slot. However, if
314  * bgw_notify_pid is set, the process that registered the worker may
315  * need to know that we've processed the terminate request, so be sure
316  * to signal it.
317  */
318  if (slot->terminate)
319  {
320  int notify_pid;
321 
322  /*
323  * We need a memory barrier here to make sure that the load of
324  * bgw_notify_pid and the update of parallel_terminate_count
325  * complete before the store to in_use.
326  */
327  notify_pid = slot->worker.bgw_notify_pid;
328  if ((slot->worker.bgw_flags & BGWORKER_CLASS_PARALLEL) != 0)
330  slot->pid = 0;
331 
333  slot->in_use = false;
334 
335  if (notify_pid != 0)
336  kill(notify_pid, SIGUSR1);
337 
338  continue;
339  }
340 
341  /*
342  * Copy the registration data into the registered workers list.
343  */
344  rw = malloc(sizeof(RegisteredBgWorker));
345  if (rw == NULL)
346  {
347  ereport(LOG,
348  (errcode(ERRCODE_OUT_OF_MEMORY),
349  errmsg("out of memory")));
350  return;
351  }
352 
353  /*
354  * Copy strings in a paranoid way. If shared memory is corrupted, the
355  * source data might not even be NUL-terminated.
356  */
358  slot->worker.bgw_name, BGW_MAXLEN);
360  slot->worker.bgw_type, BGW_MAXLEN);
365 
366  /*
367  * Copy various fixed-size fields.
368  *
369  * flags, start_time, and restart_time are examined by the postmaster,
370  * but nothing too bad will happen if they are corrupted. The
371  * remaining fields will only be examined by the child process. It
372  * might crash, but we won't.
373  */
374  rw->rw_worker.bgw_flags = slot->worker.bgw_flags;
378  memcpy(rw->rw_worker.bgw_extra, slot->worker.bgw_extra, BGW_EXTRALEN);
379 
380  /*
381  * Copy the PID to be notified about state changes, but only if the
382  * postmaster knows about a backend with that PID. It isn't an error
383  * if the postmaster doesn't know about the PID, because the backend
384  * that requested the worker could have died (or been killed) just
385  * after doing so. Nonetheless, at least until we get some experience
386  * with how this plays out in the wild, log a message at a relative
387  * high debug level.
388  */
391  {
392  elog(DEBUG1, "worker notification PID %ld is not valid",
393  (long) rw->rw_worker.bgw_notify_pid);
394  rw->rw_worker.bgw_notify_pid = 0;
395  }
396 
397  /* Initialize postmaster bookkeeping. */
398  rw->rw_backend = NULL;
399  rw->rw_pid = 0;
400  rw->rw_child_slot = 0;
401  rw->rw_crashed_at = 0;
402  rw->rw_shmem_slot = slotno;
403  rw->rw_terminate = false;
404 
405  /* Log it! */
406  ereport(DEBUG1,
407  (errmsg_internal("registering background worker \"%s\"",
408  rw->rw_worker.bgw_name)));
409 
411  }
412 }
char bgw_extra[BGW_EXTRALEN]
Definition: bgworker.h:98
struct bkend * rw_backend
#define DEBUG1
Definition: elog.h:25
#define SIGUSR1
Definition: win32_port.h:171
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
static void slist_push_head(slist_head *head, slist_node *node)
Definition: ilist.h:593
int bgw_restart_time
Definition: bgworker.h:94
int errcode(int sqlerrcode)
Definition: elog.c:698
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
#define kill(pid, sig)
Definition: win32_port.h:454
void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz)
Definition: ascii.c:173
#define LOG
Definition: elog.h:26
char bgw_function_name[BGW_MAXLEN]
Definition: bgworker.h:96
#define malloc(a)
Definition: header.h:50
Datum bgw_main_arg
Definition: bgworker.h:97
void ReportBackgroundWorkerPID(RegisteredBgWorker *rw)
Definition: bgworker.c:461
bool PostmasterMarkPIDForWorkerNotify(int pid)
Definition: postmaster.c:6095
slist_head BackgroundWorkerList
Definition: bgworker.c:42
static RegisteredBgWorker * FindRegisteredWorkerBySlotNumber(int slotno)
Definition: bgworker.c:217
#define ereport(elevel,...)
Definition: elog.h:157
int errmsg_internal(const char *fmt,...)
Definition: elog.c:996
#define pg_memory_barrier()
Definition: atomics.h:145
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
BackgroundWorker worker
Definition: bgworker.c:82
#define pg_read_barrier()
Definition: atomics.h:158
#define BGW_MAXLEN
Definition: bgworker.h:85
BgWorkerStartTime bgw_start_time
Definition: bgworker.h:93
char bgw_type[BGW_MAXLEN]
Definition: bgworker.h:91
int errmsg(const char *fmt,...)
Definition: elog.c:909
uint32 parallel_terminate_count
Definition: bgworker.c:100
pid_t bgw_notify_pid
Definition: bgworker.h:99
#define elog(elevel,...)
Definition: elog.h:232
int max_worker_processes
Definition: globals.c:137
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101
char bgw_library_name[BGW_MAXLEN]
Definition: bgworker.h:95
#define BGW_EXTRALEN
Definition: bgworker.h:86

◆ BackgroundWorkerStopNotifications()

void BackgroundWorkerStopNotifications ( pid_t  pid)

Definition at line 514 of file bgworker.c.

References BackgroundWorker::bgw_notify_pid, slist_iter::cur, RegisteredBgWorker::rw_worker, slist_container, and slist_foreach.

Referenced by CleanupBackend(), and CleanupBackgroundWorker().

515 {
516  slist_iter siter;
517 
519  {
520  RegisteredBgWorker *rw;
521 
522  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
523  if (rw->rw_worker.bgw_notify_pid == pid)
524  rw->rw_worker.bgw_notify_pid = 0;
525  }
526 }
slist_node * cur
Definition: ilist.h:226
slist_head BackgroundWorkerList
Definition: bgworker.c:42
#define slist_container(type, membername, ptr)
Definition: ilist.h:693
#define slist_foreach(iter, lhead)
Definition: ilist.h:719
pid_t bgw_notify_pid
Definition: bgworker.h:99
BackgroundWorker rw_worker

◆ bgworker_die()

static void bgworker_die ( SIGNAL_ARGS  )
static

Definition at line 717 of file bgworker.c.

References BackgroundWorker::bgw_type, BlockSig, ereport, errcode(), errmsg(), FATAL, MyBgworkerEntry, and PG_SETMASK.

Referenced by StartBackgroundWorker().

718 {
720 
721  ereport(FATAL,
722  (errcode(ERRCODE_ADMIN_SHUTDOWN),
723  errmsg("terminating background worker \"%s\" due to administrator command",
725 }
int errcode(int sqlerrcode)
Definition: elog.c:698
BackgroundWorker * MyBgworkerEntry
Definition: postmaster.c:195
#define PG_SETMASK(mask)
Definition: pqsignal.h:19
#define FATAL
Definition: elog.h:49
sigset_t BlockSig
Definition: pqsignal.c:22
#define ereport(elevel,...)
Definition: elog.h:157
char bgw_type[BGW_MAXLEN]
Definition: bgworker.h:91
int errmsg(const char *fmt,...)
Definition: elog.c:909

◆ FindRegisteredWorkerBySlotNumber()

static RegisteredBgWorker* FindRegisteredWorkerBySlotNumber ( int  slotno)
static

Definition at line 217 of file bgworker.c.

References slist_iter::cur, RegisteredBgWorker::rw_shmem_slot, slist_container, and slist_foreach.

Referenced by BackgroundWorkerStateChange().

218 {
219  slist_iter siter;
220 
222  {
223  RegisteredBgWorker *rw;
224 
225  rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
226  if (rw->rw_shmem_slot == slotno)
227  return rw;
228  }
229 
230  return NULL;
231 }
slist_node * cur
Definition: ilist.h:226
slist_head BackgroundWorkerList
Definition: bgworker.c:42
#define slist_container(type, membername, ptr)
Definition: ilist.h:693
#define slist_foreach(iter, lhead)
Definition: ilist.h:719

◆ ForgetBackgroundWorker()

void ForgetBackgroundWorker ( slist_mutable_iter cur)

Definition at line 426 of file bgworker.c.

References Assert, BackgroundWorker::bgw_flags, BackgroundWorker::bgw_name, BGWORKER_CLASS_PARALLEL, slist_mutable_iter::cur, DEBUG1, ereport, errmsg_internal(), free, BackgroundWorkerSlot::in_use, max_worker_processes, BackgroundWorkerArray::parallel_terminate_count, pg_memory_barrier, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_worker, slist_container, slist_delete_current(), and BackgroundWorkerArray::slot.

Referenced by DetermineSleepTime(), ForgetUnstartedBackgroundWorkers(), maybe_start_bgworkers(), ReportBackgroundWorkerExit(), and ResetBackgroundWorkerCrashTimes().

427 {
428  RegisteredBgWorker *rw;
429  BackgroundWorkerSlot *slot;
430 
431  rw = slist_container(RegisteredBgWorker, rw_lnode, cur->cur);
432 
435  Assert(slot->in_use);
436 
437  /*
438  * We need a memory barrier here to make sure that the update of
439  * parallel_terminate_count completes before the store to in_use.
440  */
443 
445  slot->in_use = false;
446 
447  ereport(DEBUG1,
448  (errmsg_internal("unregistering background worker \"%s\"",
449  rw->rw_worker.bgw_name)));
450 
452  free(rw);
453 }
#define DEBUG1
Definition: elog.h:25
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
slist_node * cur
Definition: ilist.h:241
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
#define slist_container(type, membername, ptr)
Definition: ilist.h:693
#define ereport(elevel,...)
Definition: elog.h:157
#define free(a)
Definition: header.h:65
int errmsg_internal(const char *fmt,...)
Definition: elog.c:996
#define pg_memory_barrier()
Definition: atomics.h:145
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
#define Assert(condition)
Definition: c.h:804
uint32 parallel_terminate_count
Definition: bgworker.c:100
int max_worker_processes
Definition: globals.c:137
static void slist_delete_current(slist_mutable_iter *iter)
Definition: ilist.h:671
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ ForgetUnstartedBackgroundWorkers()

void ForgetUnstartedBackgroundWorkers ( void  )

Definition at line 541 of file bgworker.c.

References Assert, BackgroundWorker::bgw_notify_pid, slist_mutable_iter::cur, ForgetBackgroundWorker(), InvalidPid, kill, max_worker_processes, BackgroundWorkerSlot::pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_worker, SIGUSR1, slist_container, slist_foreach_modify, and BackgroundWorkerArray::slot.

Referenced by PostmasterStateMachine().

542 {
543  slist_mutable_iter iter;
544 
546  {
547  RegisteredBgWorker *rw;
548  BackgroundWorkerSlot *slot;
549 
550  rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
553 
554  /* If it's not yet started, and there's someone waiting ... */
555  if (slot->pid == InvalidPid &&
556  rw->rw_worker.bgw_notify_pid != 0)
557  {
558  /* ... then zap it, and notify the waiter */
559  int notify_pid = rw->rw_worker.bgw_notify_pid;
560 
561  ForgetBackgroundWorker(&iter);
562  if (notify_pid != 0)
563  kill(notify_pid, SIGUSR1);
564  }
565  }
566 }
#define SIGUSR1
Definition: win32_port.h:171
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
slist_node * cur
Definition: ilist.h:241
#define kill(pid, sig)
Definition: win32_port.h:454
#define slist_foreach_modify(iter, lhead)
Definition: ilist.h:735
slist_head BackgroundWorkerList
Definition: bgworker.c:42
void ForgetBackgroundWorker(slist_mutable_iter *cur)
Definition: bgworker.c:426
#define slist_container(type, membername, ptr)
Definition: ilist.h:693
#define Assert(condition)
Definition: c.h:804
pid_t bgw_notify_pid
Definition: bgworker.h:99
int max_worker_processes
Definition: globals.c:137
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101
#define InvalidPid
Definition: miscadmin.h:32

◆ GetBackgroundWorkerPid()

BgwHandleStatus GetBackgroundWorkerPid ( BackgroundWorkerHandle handle,
pid_t *  pidp 
)

Definition at line 1085 of file bgworker.c.

References Assert, BGWH_NOT_YET_STARTED, BGWH_STARTED, BGWH_STOPPED, BackgroundWorkerSlot::generation, BackgroundWorkerHandle::generation, BackgroundWorkerSlot::in_use, InvalidPid, LW_SHARED, LWLockAcquire(), LWLockRelease(), max_worker_processes, BackgroundWorkerSlot::pid, BackgroundWorkerArray::slot, and BackgroundWorkerHandle::slot.

Referenced by check_worker_status(), shm_mq_counterparty_gone(), shm_mq_wait_internal(), WaitForBackgroundWorkerShutdown(), WaitForBackgroundWorkerStartup(), WaitForParallelWorkersToAttach(), WaitForParallelWorkersToFinish(), and WaitForReplicationWorkerAttach().

1086 {
1087  BackgroundWorkerSlot *slot;
1088  pid_t pid;
1089 
1090  Assert(handle->slot < max_worker_processes);
1091  slot = &BackgroundWorkerData->slot[handle->slot];
1092 
1093  /*
1094  * We could probably arrange to synchronize access to data using memory
1095  * barriers only, but for now, let's just keep it simple and grab the
1096  * lock. It seems unlikely that there will be enough traffic here to
1097  * result in meaningful contention.
1098  */
1099  LWLockAcquire(BackgroundWorkerLock, LW_SHARED);
1100 
1101  /*
1102  * The generation number can't be concurrently changed while we hold the
1103  * lock. The pid, which is updated by the postmaster, can change at any
1104  * time, but we assume such changes are atomic. So the value we read
1105  * won't be garbage, but it might be out of date by the time the caller
1106  * examines it (but that's unavoidable anyway).
1107  *
1108  * The in_use flag could be in the process of changing from true to false,
1109  * but if it is already false then it can't change further.
1110  */
1111  if (handle->generation != slot->generation || !slot->in_use)
1112  pid = 0;
1113  else
1114  pid = slot->pid;
1115 
1116  /* All done. */
1117  LWLockRelease(BackgroundWorkerLock);
1118 
1119  if (pid == 0)
1120  return BGWH_STOPPED;
1121  else if (pid == InvalidPid)
1122  return BGWH_NOT_YET_STARTED;
1123  *pidp = pid;
1124  return BGWH_STARTED;
1125 }
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1816
#define Assert(condition)
Definition: c.h:804
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1203
int max_worker_processes
Definition: globals.c:137
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101
#define InvalidPid
Definition: miscadmin.h:32

◆ GetBackgroundWorkerTypeByPid()

const char* GetBackgroundWorkerTypeByPid ( pid_t  pid)

Definition at line 1299 of file bgworker.c.

References BGW_MAXLEN, BackgroundWorker::bgw_type, LW_SHARED, LWLockAcquire(), LWLockRelease(), BackgroundWorkerSlot::pid, BackgroundWorkerArray::slot, BackgroundWorkerArray::total_slots, and BackgroundWorkerSlot::worker.

Referenced by pg_stat_get_activity().

1300 {
1301  int slotno;
1302  bool found = false;
1303  static char result[BGW_MAXLEN];
1304 
1305  LWLockAcquire(BackgroundWorkerLock, LW_SHARED);
1306 
1307  for (slotno = 0; slotno < BackgroundWorkerData->total_slots; slotno++)
1308  {
1310 
1311  if (slot->pid > 0 && slot->pid == pid)
1312  {
1313  strcpy(result, slot->worker.bgw_type);
1314  found = true;
1315  break;
1316  }
1317  }
1318 
1319  LWLockRelease(BackgroundWorkerLock);
1320 
1321  if (!found)
1322  return NULL;
1323 
1324  return result;
1325 }
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1816
BackgroundWorker worker
Definition: bgworker.c:82
#define BGW_MAXLEN
Definition: bgworker.h:85
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1203
char bgw_type[BGW_MAXLEN]
Definition: bgworker.h:91
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ LookupBackgroundWorkerFunction()

static bgworker_main_type LookupBackgroundWorkerFunction ( const char *  libraryname,
const char *  funcname 
)
static

Definition at line 1265 of file bgworker.c.

References elog, ERROR, fn_addr, fn_name, i, InternalBGWorkers, lengthof, and load_external_function().

Referenced by StartBackgroundWorker().

1266 {
1267  /*
1268  * If the function is to be loaded from postgres itself, search the
1269  * InternalBGWorkers array.
1270  */
1271  if (strcmp(libraryname, "postgres") == 0)
1272  {
1273  int i;
1274 
1275  for (i = 0; i < lengthof(InternalBGWorkers); i++)
1276  {
1277  if (strcmp(InternalBGWorkers[i].fn_name, funcname) == 0)
1278  return InternalBGWorkers[i].fn_addr;
1279  }
1280 
1281  /* We can only reach this by programming error. */
1282  elog(ERROR, "internal function \"%s\" not found", funcname);
1283  }
1284 
1285  /* Otherwise load from external library. */
1286  return (bgworker_main_type)
1287  load_external_function(libraryname, funcname, true, NULL);
1288 }
#define lengthof(array)
Definition: c.h:734
const char * fn_name
Definition: bgworker.c:118
#define ERROR
Definition: elog.h:46
void * load_external_function(const char *filename, const char *funcname, bool signalNotFound, void **filehandle)
Definition: dfmgr.c:107
static const struct @15 InternalBGWorkers[]
bgworker_main_type fn_addr
Definition: bgworker.c:119
#define elog(elevel,...)
Definition: elog.h:232
int i
void(* bgworker_main_type)(Datum main_arg)
Definition: bgworker.h:71

◆ RegisterBackgroundWorker()

void RegisterBackgroundWorker ( BackgroundWorker worker)

Definition at line 889 of file bgworker.c.

References BackgroundWorker::bgw_library_name, BackgroundWorker::bgw_name, BackgroundWorker::bgw_notify_pid, DEBUG1, ereport, errcode(), errdetail_plural(), errhint(), errmsg(), errmsg_internal(), IsUnderPostmaster, LOG, malloc, max_worker_processes, process_shared_preload_libraries_in_progress, RegisteredBgWorker::rw_backend, RegisteredBgWorker::rw_child_slot, RegisteredBgWorker::rw_crashed_at, RegisteredBgWorker::rw_lnode, RegisteredBgWorker::rw_pid, RegisteredBgWorker::rw_terminate, RegisteredBgWorker::rw_worker, SanityCheckBackgroundWorker(), slist_push_head(), and BackgroundWorkerSlot::worker.

Referenced by _PG_init(), ApplyLauncherRegister(), and apw_start_leader_worker().

890 {
891  RegisteredBgWorker *rw;
892  static int numworkers = 0;
893 
894  if (!IsUnderPostmaster)
895  ereport(DEBUG1,
896  (errmsg_internal("registering background worker \"%s\"", worker->bgw_name)));
897 
899  strcmp(worker->bgw_library_name, "postgres") != 0)
900  {
901  if (!IsUnderPostmaster)
902  ereport(LOG,
903  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
904  errmsg("background worker \"%s\": must be registered in shared_preload_libraries",
905  worker->bgw_name)));
906  return;
907  }
908 
909  if (!SanityCheckBackgroundWorker(worker, LOG))
910  return;
911 
912  if (worker->bgw_notify_pid != 0)
913  {
914  ereport(LOG,
915  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
916  errmsg("background worker \"%s\": only dynamic background workers can request notification",
917  worker->bgw_name)));
918  return;
919  }
920 
921  /*
922  * Enforce maximum number of workers. Note this is overly restrictive: we
923  * could allow more non-shmem-connected workers, because these don't count
924  * towards the MAX_BACKENDS limit elsewhere. For now, it doesn't seem
925  * important to relax this restriction.
926  */
927  if (++numworkers > max_worker_processes)
928  {
929  ereport(LOG,
930  (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
931  errmsg("too many background workers"),
932  errdetail_plural("Up to %d background worker can be registered with the current settings.",
933  "Up to %d background workers can be registered with the current settings.",
936  errhint("Consider increasing the configuration parameter \"max_worker_processes\".")));
937  return;
938  }
939 
940  /*
941  * Copy the registration data into the registered workers list.
942  */
943  rw = malloc(sizeof(RegisteredBgWorker));
944  if (rw == NULL)
945  {
946  ereport(LOG,
947  (errcode(ERRCODE_OUT_OF_MEMORY),
948  errmsg("out of memory")));
949  return;
950  }
951 
952  rw->rw_worker = *worker;
953  rw->rw_backend = NULL;
954  rw->rw_pid = 0;
955  rw->rw_child_slot = 0;
956  rw->rw_crashed_at = 0;
957  rw->rw_terminate = false;
958 
960 }
struct bkend * rw_backend
#define DEBUG1
Definition: elog.h:25
int errhint(const char *fmt,...)
Definition: elog.c:1156
bool process_shared_preload_libraries_in_progress
Definition: miscinit.c:1598
static void slist_push_head(slist_head *head, slist_node *node)
Definition: ilist.h:593
int errcode(int sqlerrcode)
Definition: elog.c:698
#define LOG
Definition: elog.h:26
#define malloc(a)
Definition: header.h:50
slist_head BackgroundWorkerList
Definition: bgworker.c:42
bool IsUnderPostmaster
Definition: globals.c:112
static bool SanityCheckBackgroundWorker(BackgroundWorker *worker, int elevel)
Definition: bgworker.c:652
#define ereport(elevel,...)
Definition: elog.h:157
int errmsg_internal(const char *fmt,...)
Definition: elog.c:996
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
int errdetail_plural(const char *fmt_singular, const char *fmt_plural, unsigned long n,...)
Definition: elog.c:1134
int errmsg(const char *fmt,...)
Definition: elog.c:909
pid_t bgw_notify_pid
Definition: bgworker.h:99
int max_worker_processes
Definition: globals.c:137
BackgroundWorker rw_worker
char bgw_library_name[BGW_MAXLEN]
Definition: bgworker.h:95

◆ RegisterDynamicBackgroundWorker()

bool RegisterDynamicBackgroundWorker ( BackgroundWorker worker,
BackgroundWorkerHandle **  handle 
)

Definition at line 973 of file bgworker.c.

References Assert, BackgroundWorker::bgw_flags, BGWORKER_CLASS_PARALLEL, ERROR, BackgroundWorkerSlot::generation, BackgroundWorkerSlot::in_use, InvalidPid, IsUnderPostmaster, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MAX_PARALLEL_WORKER_LIMIT, max_parallel_workers, palloc(), BackgroundWorkerArray::parallel_register_count, BackgroundWorkerArray::parallel_terminate_count, pg_write_barrier, BackgroundWorkerSlot::pid, PMSIGNAL_BACKGROUND_WORKER_CHANGE, SanityCheckBackgroundWorker(), SendPostmasterSignal(), BackgroundWorkerArray::slot, success, BackgroundWorkerSlot::terminate, BackgroundWorkerArray::total_slots, and BackgroundWorkerSlot::worker.

Referenced by apw_start_database_worker(), apw_start_leader_worker(), LaunchParallelWorkers(), logicalrep_worker_launch(), setup_background_workers(), and worker_spi_launch().

975 {
976  int slotno;
977  bool success = false;
978  bool parallel;
979  uint64 generation = 0;
980 
981  /*
982  * We can't register dynamic background workers from the postmaster. If
983  * this is a standalone backend, we're the only process and can't start
984  * any more. In a multi-process environment, it might be theoretically
985  * possible, but we don't currently support it due to locking
986  * considerations; see comments on the BackgroundWorkerSlot data
987  * structure.
988  */
989  if (!IsUnderPostmaster)
990  return false;
991 
992  if (!SanityCheckBackgroundWorker(worker, ERROR))
993  return false;
994 
995  parallel = (worker->bgw_flags & BGWORKER_CLASS_PARALLEL) != 0;
996 
997  LWLockAcquire(BackgroundWorkerLock, LW_EXCLUSIVE);
998 
999  /*
1000  * If this is a parallel worker, check whether there are already too many
1001  * parallel workers; if so, don't register another one. Our view of
1002  * parallel_terminate_count may be slightly stale, but that doesn't really
1003  * matter: we would have gotten the same result if we'd arrived here
1004  * slightly earlier anyway. There's no help for it, either, since the
1005  * postmaster must not take locks; a memory barrier wouldn't guarantee
1006  * anything useful.
1007  */
1008  if (parallel && (BackgroundWorkerData->parallel_register_count -
1011  {
1015  LWLockRelease(BackgroundWorkerLock);
1016  return false;
1017  }
1018 
1019  /*
1020  * Look for an unused slot. If we find one, grab it.
1021  */
1022  for (slotno = 0; slotno < BackgroundWorkerData->total_slots; ++slotno)
1023  {
1025 
1026  if (!slot->in_use)
1027  {
1028  memcpy(&slot->worker, worker, sizeof(BackgroundWorker));
1029  slot->pid = InvalidPid; /* indicates not started yet */
1030  slot->generation++;
1031  slot->terminate = false;
1032  generation = slot->generation;
1033  if (parallel)
1035 
1036  /*
1037  * Make sure postmaster doesn't see the slot as in use before it
1038  * sees the new contents.
1039  */
1040  pg_write_barrier();
1041 
1042  slot->in_use = true;
1043  success = true;
1044  break;
1045  }
1046  }
1047 
1048  LWLockRelease(BackgroundWorkerLock);
1049 
1050  /* If we found a slot, tell the postmaster to notice the change. */
1051  if (success)
1053 
1054  /*
1055  * If we found a slot and the user has provided a handle, initialize it.
1056  */
1057  if (success && handle)
1058  {
1059  *handle = palloc(sizeof(BackgroundWorkerHandle));
1060  (*handle)->slot = slotno;
1061  (*handle)->generation = generation;
1062  }
1063 
1064  return success;
1065 }
int max_parallel_workers
Definition: globals.c:138
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1816
#define ERROR
Definition: elog.h:46
uint32 parallel_register_count
Definition: bgworker.c:99
bool IsUnderPostmaster
Definition: globals.c:112
static bool SanityCheckBackgroundWorker(BackgroundWorker *worker, int elevel)
Definition: bgworker.c:652
#define Assert(condition)
Definition: c.h:804
BackgroundWorker worker
Definition: bgworker.c:82
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1203
void * palloc(Size size)
Definition: mcxt.c:1062
uint32 parallel_terminate_count
Definition: bgworker.c:100
#define pg_write_barrier()
Definition: atomics.h:159
void SendPostmasterSignal(PMSignalReason reason)
Definition: pmsignal.c:153
#define MAX_PARALLEL_WORKER_LIMIT
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101
static bool success
Definition: initdb.c:165
#define InvalidPid
Definition: miscadmin.h:32

◆ ReportBackgroundWorkerExit()

void ReportBackgroundWorkerExit ( slist_mutable_iter cur)

Definition at line 480 of file bgworker.c.

References Assert, BGW_NEVER_RESTART, BackgroundWorker::bgw_notify_pid, BackgroundWorker::bgw_restart_time, slist_mutable_iter::cur, ForgetBackgroundWorker(), kill, max_worker_processes, BackgroundWorkerSlot::pid, RegisteredBgWorker::rw_pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_terminate, RegisteredBgWorker::rw_worker, SIGUSR1, slist_container, and BackgroundWorkerArray::slot.

Referenced by CleanupBackgroundWorker().

481 {
482  RegisteredBgWorker *rw;
483  BackgroundWorkerSlot *slot;
484  int notify_pid;
485 
486  rw = slist_container(RegisteredBgWorker, rw_lnode, cur->cur);
487 
490  slot->pid = rw->rw_pid;
491  notify_pid = rw->rw_worker.bgw_notify_pid;
492 
493  /*
494  * If this worker is slated for deregistration, do that before notifying
495  * the process which started it. Otherwise, if that process tries to
496  * reuse the slot immediately, it might not be available yet. In theory
497  * that could happen anyway if the process checks slot->pid at just the
498  * wrong moment, but this makes the window narrower.
499  */
500  if (rw->rw_terminate ||
503 
504  if (notify_pid != 0)
505  kill(notify_pid, SIGUSR1);
506 }
#define SIGUSR1
Definition: win32_port.h:171
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
slist_node * cur
Definition: ilist.h:241
int bgw_restart_time
Definition: bgworker.h:94
#define kill(pid, sig)
Definition: win32_port.h:454
void ForgetBackgroundWorker(slist_mutable_iter *cur)
Definition: bgworker.c:426
#define BGW_NEVER_RESTART
Definition: bgworker.h:84
#define slist_container(type, membername, ptr)
Definition: ilist.h:693
#define Assert(condition)
Definition: c.h:804
pid_t bgw_notify_pid
Definition: bgworker.h:99
int max_worker_processes
Definition: globals.c:137
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ ReportBackgroundWorkerPID()

void ReportBackgroundWorkerPID ( RegisteredBgWorker rw)

Definition at line 461 of file bgworker.c.

References Assert, BackgroundWorker::bgw_notify_pid, kill, max_worker_processes, BackgroundWorkerSlot::pid, RegisteredBgWorker::rw_pid, RegisteredBgWorker::rw_shmem_slot, RegisteredBgWorker::rw_worker, SIGUSR1, and BackgroundWorkerArray::slot.

Referenced by BackgroundWorkerStateChange(), and do_start_bgworker().

462 {
463  BackgroundWorkerSlot *slot;
464 
467  slot->pid = rw->rw_pid;
468 
469  if (rw->rw_worker.bgw_notify_pid != 0)
471 }
#define SIGUSR1
Definition: win32_port.h:171
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
#define kill(pid, sig)
Definition: win32_port.h:454
#define Assert(condition)
Definition: c.h:804
pid_t bgw_notify_pid
Definition: bgworker.h:99
int max_worker_processes
Definition: globals.c:137
BackgroundWorker rw_worker
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ ResetBackgroundWorkerCrashTimes()

void ResetBackgroundWorkerCrashTimes ( void  )

Definition at line 579 of file bgworker.c.

References Assert, BackgroundWorker::bgw_flags, BGW_NEVER_RESTART, BackgroundWorker::bgw_notify_pid, BackgroundWorker::bgw_restart_time, BGWORKER_CLASS_PARALLEL, slist_mutable_iter::cur, ForgetBackgroundWorker(), BackgroundWorkerSlot::in_use, RegisteredBgWorker::rw_crashed_at, RegisteredBgWorker::rw_worker, slist_container, slist_foreach_modify, BackgroundWorkerArray::slot, and BackgroundWorkerSlot::worker.

Referenced by PostmasterStateMachine().

580 {
581  slist_mutable_iter iter;
582 
584  {
585  RegisteredBgWorker *rw;
586 
587  rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
588 
590  {
591  /*
592  * Workers marked BGW_NEVER_RESTART shouldn't get relaunched after
593  * the crash, so forget about them. (If we wait until after the
594  * crash to forget about them, and they are parallel workers,
595  * parallel_terminate_count will get incremented after we've
596  * already zeroed parallel_register_count, which would be bad.)
597  */
598  ForgetBackgroundWorker(&iter);
599  }
600  else
601  {
602  /*
603  * The accounting which we do via parallel_register_count and
604  * parallel_terminate_count would get messed up if a worker marked
605  * parallel could survive a crash and restart cycle. All such
606  * workers should be marked BGW_NEVER_RESTART, and thus control
607  * should never reach this branch.
608  */
610 
611  /*
612  * Allow this worker to be restarted immediately after we finish
613  * resetting.
614  */
615  rw->rw_crashed_at = 0;
616 
617  /*
618  * If there was anyone waiting for it, they're history.
619  */
620  rw->rw_worker.bgw_notify_pid = 0;
621  }
622  }
623 }
slist_node * cur
Definition: ilist.h:241
int bgw_restart_time
Definition: bgworker.h:94
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
#define slist_foreach_modify(iter, lhead)
Definition: ilist.h:735
slist_head BackgroundWorkerList
Definition: bgworker.c:42
void ForgetBackgroundWorker(slist_mutable_iter *cur)
Definition: bgworker.c:426
#define BGW_NEVER_RESTART
Definition: bgworker.h:84
#define slist_container(type, membername, ptr)
Definition: ilist.h:693
#define Assert(condition)
Definition: c.h:804
pid_t bgw_notify_pid
Definition: bgworker.h:99
BackgroundWorker rw_worker

◆ SanityCheckBackgroundWorker()

static bool SanityCheckBackgroundWorker ( BackgroundWorker worker,
int  elevel 
)
static

Definition at line 652 of file bgworker.c.

References BackgroundWorker::bgw_flags, BackgroundWorker::bgw_name, BGW_NEVER_RESTART, BackgroundWorker::bgw_restart_time, BackgroundWorker::bgw_start_time, BackgroundWorker::bgw_type, BGWORKER_BACKEND_DATABASE_CONNECTION, BGWORKER_CLASS_PARALLEL, BGWORKER_SHMEM_ACCESS, BgWorkerStart_PostmasterStart, ereport, errcode(), errmsg(), and USECS_PER_DAY.

Referenced by RegisterBackgroundWorker(), and RegisterDynamicBackgroundWorker().

653 {
654  /* sanity check for flags */
656  {
657  if (!(worker->bgw_flags & BGWORKER_SHMEM_ACCESS))
658  {
659  ereport(elevel,
660  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
661  errmsg("background worker \"%s\": must attach to shared memory in order to request a database connection",
662  worker->bgw_name)));
663  return false;
664  }
665 
667  {
668  ereport(elevel,
669  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
670  errmsg("background worker \"%s\": cannot request database access if starting at postmaster start",
671  worker->bgw_name)));
672  return false;
673  }
674 
675  /* XXX other checks? */
676  }
677 
678  if ((worker->bgw_restart_time < 0 &&
679  worker->bgw_restart_time != BGW_NEVER_RESTART) ||
680  (worker->bgw_restart_time > USECS_PER_DAY / 1000))
681  {
682  ereport(elevel,
683  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
684  errmsg("background worker \"%s\": invalid restart interval",
685  worker->bgw_name)));
686  return false;
687  }
688 
689  /*
690  * Parallel workers may not be configured for restart, because the
691  * parallel_register_count/parallel_terminate_count accounting can't
692  * handle parallel workers lasting through a crash-and-restart cycle.
693  */
694  if (worker->bgw_restart_time != BGW_NEVER_RESTART &&
695  (worker->bgw_flags & BGWORKER_CLASS_PARALLEL) != 0)
696  {
697  ereport(elevel,
698  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
699  errmsg("background worker \"%s\": parallel workers may not be configured for restart",
700  worker->bgw_name)));
701  return false;
702  }
703 
704  /*
705  * If bgw_type is not filled in, use bgw_name.
706  */
707  if (strcmp(worker->bgw_type, "") == 0)
708  strcpy(worker->bgw_type, worker->bgw_name);
709 
710  return true;
711 }
int bgw_restart_time
Definition: bgworker.h:94
int errcode(int sqlerrcode)
Definition: elog.c:698
#define BGWORKER_CLASS_PARALLEL
Definition: bgworker.h:67
#define BGWORKER_SHMEM_ACCESS
Definition: bgworker.h:52
#define BGW_NEVER_RESTART
Definition: bgworker.h:84
#define USECS_PER_DAY
Definition: timestamp.h:91
static int elevel
Definition: vacuumlazy.c:403
#define ereport(elevel,...)
Definition: elog.h:157
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
#define BGWORKER_BACKEND_DATABASE_CONNECTION
Definition: bgworker.h:59
BgWorkerStartTime bgw_start_time
Definition: bgworker.h:93
char bgw_type[BGW_MAXLEN]
Definition: bgworker.h:91
int errmsg(const char *fmt,...)
Definition: elog.c:909

◆ StartBackgroundWorker()

void StartBackgroundWorker ( void  )

Definition at line 734 of file bgworker.c.

References B_BG_WORKER, BackgroundWorkerUnblockSignals(), BaseInit(), BackgroundWorker::bgw_flags, BackgroundWorker::bgw_function_name, BackgroundWorker::bgw_library_name, BackgroundWorker::bgw_main_arg, BackgroundWorker::bgw_name, BGWORKER_BACKEND_DATABASE_CONNECTION, bgworker_die(), BGWORKER_SHMEM_ACCESS, dsm_detach_all(), elog, EmitErrorReport(), error_context_stack, FATAL, FloatExceptionHandler(), HOLD_INTERRUPTS, init_ps_display(), InitializeTimeouts(), InitProcess(), InitProcessing, IsBackgroundWorker, LookupBackgroundWorkerFunction(), MyBackendType, MyBgworkerEntry, PG_exception_stack, pg_usleep(), PGSharedMemoryDetach(), PostAuthDelay, pqsignal(), proc_exit(), procsignal_sigusr1_handler(), SetProcessingMode, ShutdownLatchSupport(), SIG_DFL, SIG_IGN, SIGCHLD, SIGHUP, SIGPIPE, SIGUSR1, SIGUSR2, StatementCancelHandler(), and BackgroundWorkerSlot::worker.

Referenced by BackendRun(), and do_start_bgworker().

735 {
736  sigjmp_buf local_sigjmp_buf;
738  bgworker_main_type entrypt;
739 
740  if (worker == NULL)
741  elog(FATAL, "unable to find bgworker entry");
742 
743  IsBackgroundWorker = true;
744 
746  init_ps_display(worker->bgw_name);
747 
748  /*
749  * If we're not supposed to have shared memory access, then detach from
750  * shared memory. If we didn't request shared memory access, the
751  * postmaster won't force a cluster-wide restart if we exit unexpectedly,
752  * so we'd better make sure that we don't mess anything up that would
753  * require that sort of cleanup.
754  */
755  if ((worker->bgw_flags & BGWORKER_SHMEM_ACCESS) == 0)
756  {
758  dsm_detach_all();
760  }
761 
763 
764  /* Apply PostAuthDelay */
765  if (PostAuthDelay > 0)
766  pg_usleep(PostAuthDelay * 1000000L);
767 
768  /*
769  * Set up signal handlers.
770  */
772  {
773  /*
774  * SIGINT is used to signal canceling the current action
775  */
779 
780  /* XXX Any other handlers needed here? */
781  }
782  else
783  {
784  pqsignal(SIGINT, SIG_IGN);
786  pqsignal(SIGFPE, SIG_IGN);
787  }
788  pqsignal(SIGTERM, bgworker_die);
789  /* SIGQUIT handler was already set up by InitPostmasterChild */
791 
792  InitializeTimeouts(); /* establishes SIGALRM handler */
793 
797 
798  /*
799  * If an exception is encountered, processing resumes here.
800  *
801  * We just need to clean up, report the error, and go away.
802  */
803  if (sigsetjmp(local_sigjmp_buf, 1) != 0)
804  {
805  /* Since not using PG_TRY, must reset error stack by hand */
806  error_context_stack = NULL;
807 
808  /* Prevent interrupts while cleaning up */
809  HOLD_INTERRUPTS();
810 
811  /*
812  * sigsetjmp will have blocked all signals, but we may need to accept
813  * signals while communicating with our parallel leader. Once we've
814  * done HOLD_INTERRUPTS() it should be safe to unblock signals.
815  */
817 
818  /* Report the error to the parallel leader and the server log */
819  EmitErrorReport();
820 
821  /*
822  * Do we need more cleanup here? For shmem-connected bgworkers, we
823  * will call InitProcess below, which will install ProcKill as exit
824  * callback. That will take care of releasing locks, etc.
825  */
826 
827  /* and go away */
828  proc_exit(1);
829  }
830 
831  /* We can now handle ereport(ERROR) */
832  PG_exception_stack = &local_sigjmp_buf;
833 
834  /*
835  * If the background worker request shared memory access, set that up now;
836  * else, detach all shared memory segments.
837  */
838  if (worker->bgw_flags & BGWORKER_SHMEM_ACCESS)
839  {
840  /*
841  * Early initialization. Some of this could be useful even for
842  * background workers that aren't using shared memory, but they can
843  * call the individual startup routines for those subsystems if
844  * needed.
845  */
846  BaseInit();
847 
848  /*
849  * Create a per-backend PGPROC struct in shared memory, except in the
850  * EXEC_BACKEND case where this was done in SubPostmasterMain. We must
851  * do this before we can use LWLocks (and in the EXEC_BACKEND case we
852  * already had to do some stuff with LWLocks).
853  */
854 #ifndef EXEC_BACKEND
855  InitProcess();
856 #endif
857  }
858 
859  /*
860  * Look up the entry point function, loading its library if necessary.
861  */
863  worker->bgw_function_name);
864 
865  /*
866  * Note that in normal processes, we would call InitPostgres here. For a
867  * worker, however, we don't know what database to connect to, yet; so we
868  * need to wait until the user code does it via
869  * BackgroundWorkerInitializeConnection().
870  */
871 
872  /*
873  * Now invoke the user-defined worker code
874  */
875  entrypt(worker->bgw_main_arg);
876 
877  /* ... and if it returns, we're done */
878  proc_exit(0);
879 }
void InitializeTimeouts(void)
Definition: timeout.c:435
#define SIGUSR1
Definition: win32_port.h:171
BackendType MyBackendType
Definition: miscinit.c:62
#define SIGCHLD
Definition: win32_port.h:169
void proc_exit(int code)
Definition: ipc.c:104
#define SetProcessingMode(mode)
Definition: miscadmin.h:412
BackgroundWorker * MyBgworkerEntry
Definition: postmaster.c:195
void BaseInit(void)
Definition: postinit.c:537
#define SIGPIPE
Definition: win32_port.h:164
#define SIGUSR2
Definition: win32_port.h:172
#define BGWORKER_SHMEM_ACCESS
Definition: bgworker.h:52
char bgw_function_name[BGW_MAXLEN]
Definition: bgworker.h:96
void PGSharedMemoryDetach(void)
Definition: sysv_shmem.c:909
void StatementCancelHandler(SIGNAL_ARGS)
Definition: postgres.c:2949
bool IsBackgroundWorker
Definition: globals.c:114
ErrorContextCallback * error_context_stack
Definition: elog.c:93
void pg_usleep(long microsec)
Definition: signal.c:53
Datum bgw_main_arg
Definition: bgworker.h:97
#define FATAL
Definition: elog.h:49
void InitProcess(void)
Definition: proc.c:303
#define SIGHUP
Definition: win32_port.h:159
static bgworker_main_type LookupBackgroundWorkerFunction(const char *libraryname, const char *funcname)
Definition: bgworker.c:1265
#define SIG_IGN
Definition: win32_port.h:156
int PostAuthDelay
Definition: postgres.c:103
void EmitErrorReport(void)
Definition: elog.c:1509
pqsigfunc pqsignal(int signum, pqsigfunc handler)
Definition: signal.c:170
#define SIG_DFL
Definition: win32_port.h:154
char bgw_name[BGW_MAXLEN]
Definition: bgworker.h:90
#define BGWORKER_BACKEND_DATABASE_CONNECTION
Definition: bgworker.h:59
void dsm_detach_all(void)
Definition: dsm.c:741
sigjmp_buf * PG_exception_stack
Definition: elog.c:95
void ShutdownLatchSupport(void)
Definition: latch.c:308
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:131
#define elog(elevel,...)
Definition: elog.h:232
void FloatExceptionHandler(SIGNAL_ARGS)
Definition: postgres.c:2970
static void bgworker_die(SIGNAL_ARGS)
Definition: bgworker.c:717
void init_ps_display(const char *fixed_part)
Definition: ps_status.c:258
void procsignal_sigusr1_handler(SIGNAL_ARGS)
Definition: procsignal.c:642
char bgw_library_name[BGW_MAXLEN]
Definition: bgworker.h:95
void(* bgworker_main_type)(Datum main_arg)
Definition: bgworker.h:71
void BackgroundWorkerUnblockSignals(void)
Definition: postmaster.c:5741

◆ TerminateBackgroundWorker()

void TerminateBackgroundWorker ( BackgroundWorkerHandle handle)

Definition at line 1224 of file bgworker.c.

References Assert, BackgroundWorkerSlot::generation, BackgroundWorkerHandle::generation, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), max_worker_processes, PMSIGNAL_BACKGROUND_WORKER_CHANGE, SendPostmasterSignal(), BackgroundWorkerArray::slot, BackgroundWorkerHandle::slot, and BackgroundWorkerSlot::terminate.

Referenced by cleanup_background_workers(), and DestroyParallelContext().

1225 {
1226  BackgroundWorkerSlot *slot;
1227  bool signal_postmaster = false;
1228 
1229  Assert(handle->slot < max_worker_processes);
1230  slot = &BackgroundWorkerData->slot[handle->slot];
1231 
1232  /* Set terminate flag in shared memory, unless slot has been reused. */
1233  LWLockAcquire(BackgroundWorkerLock, LW_EXCLUSIVE);
1234  if (handle->generation == slot->generation)
1235  {
1236  slot->terminate = true;
1237  signal_postmaster = true;
1238  }
1239  LWLockRelease(BackgroundWorkerLock);
1240 
1241  /* Make sure the postmaster notices the change to shared memory. */
1242  if (signal_postmaster)
1244 }
static BackgroundWorkerArray * BackgroundWorkerData
Definition: bgworker.c:110
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1816
#define Assert(condition)
Definition: c.h:804
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1203
int max_worker_processes
Definition: globals.c:137
void SendPostmasterSignal(PMSignalReason reason)
Definition: pmsignal.c:153
BackgroundWorkerSlot slot[FLEXIBLE_ARRAY_MEMBER]
Definition: bgworker.c:101

◆ WaitForBackgroundWorkerShutdown()

BgwHandleStatus WaitForBackgroundWorkerShutdown ( BackgroundWorkerHandle handle)

Definition at line 1185 of file bgworker.c.

References BGWH_POSTMASTER_DIED, BGWH_STOPPED, CHECK_FOR_INTERRUPTS, GetBackgroundWorkerPid(), MyLatch, BackgroundWorkerSlot::pid, ResetLatch(), status(), WAIT_EVENT_BGWORKER_SHUTDOWN, WaitLatch(), WL_LATCH_SET, and WL_POSTMASTER_DEATH.

Referenced by apw_start_database_worker(), and WaitForParallelWorkersToExit().

1186 {
1188  int rc;
1189 
1190  for (;;)
1191  {
1192  pid_t pid;
1193 
1195 
1196  status = GetBackgroundWorkerPid(handle, &pid);
1197  if (status == BGWH_STOPPED)
1198  break;
1199 
1200  rc = WaitLatch(MyLatch,
1203 
1204  if (rc & WL_POSTMASTER_DEATH)
1205  {
1206  status = BGWH_POSTMASTER_DIED;
1207  break;
1208  }
1209 
1211  }
1212 
1213  return status;
1214 }
void ResetLatch(Latch *latch)
Definition: latch.c:660
int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info)
Definition: latch.c:452
BgwHandleStatus
Definition: bgworker.h:102
#define WL_POSTMASTER_DEATH
Definition: latch.h:129
struct Latch * MyLatch
Definition: globals.c:57
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:120
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:227
#define WL_LATCH_SET
Definition: latch.h:125
BgwHandleStatus GetBackgroundWorkerPid(BackgroundWorkerHandle *handle, pid_t *pidp)
Definition: bgworker.c:1085

◆ WaitForBackgroundWorkerStartup()

BgwHandleStatus WaitForBackgroundWorkerStartup ( BackgroundWorkerHandle handle,
pid_t *  pidp 
)

Definition at line 1140 of file bgworker.c.

References BGWH_NOT_YET_STARTED, BGWH_POSTMASTER_DIED, BGWH_STARTED, CHECK_FOR_INTERRUPTS, GetBackgroundWorkerPid(), MyLatch, BackgroundWorkerSlot::pid, ResetLatch(), status(), WAIT_EVENT_BGWORKER_STARTUP, WaitLatch(), WL_LATCH_SET, and WL_POSTMASTER_DEATH.

Referenced by apw_start_leader_worker(), and worker_spi_launch().

1141 {
1143  int rc;
1144 
1145  for (;;)
1146  {
1147  pid_t pid;
1148 
1150 
1151  status = GetBackgroundWorkerPid(handle, &pid);
1152  if (status == BGWH_STARTED)
1153  *pidp = pid;
1154  if (status != BGWH_NOT_YET_STARTED)
1155  break;
1156 
1157  rc = WaitLatch(MyLatch,
1160 
1161  if (rc & WL_POSTMASTER_DEATH)
1162  {
1163  status = BGWH_POSTMASTER_DIED;
1164  break;
1165  }
1166 
1168  }
1169 
1170  return status;
1171 }
void ResetLatch(Latch *latch)
Definition: latch.c:660
int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info)
Definition: latch.c:452
BgwHandleStatus
Definition: bgworker.h:102
#define WL_POSTMASTER_DEATH
Definition: latch.h:129
struct Latch * MyLatch
Definition: globals.c:57
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:120
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:227
#define WL_LATCH_SET
Definition: latch.h:125
BgwHandleStatus GetBackgroundWorkerPid(BackgroundWorkerHandle *handle, pid_t *pidp)
Definition: bgworker.c:1085

Variable Documentation

◆ BackgroundWorkerData

BackgroundWorkerArray* BackgroundWorkerData
static

Definition at line 110 of file bgworker.c.

◆ BackgroundWorkerList

slist_head BackgroundWorkerList = SLIST_STATIC_INIT(BackgroundWorkerList)

◆ fn_addr

Definition at line 119 of file bgworker.c.

Referenced by LookupBackgroundWorkerFunction().

◆ fn_name

const char* fn_name

Definition at line 118 of file bgworker.c.

Referenced by LookupBackgroundWorkerFunction().

◆ InternalBGWorkers

const { ... } InternalBGWorkers[]
Initial value:
=
{
{
"ParallelWorkerMain", ParallelWorkerMain
},
{
"ApplyLauncherMain", ApplyLauncherMain
},
{
"ApplyWorkerMain", ApplyWorkerMain
}
}
void ApplyLauncherMain(Datum main_arg)
Definition: launcher.c:797
void ParallelWorkerMain(Datum main_arg)
Definition: parallel.c:1240
void ApplyWorkerMain(Datum main_arg)
Definition: worker.c:3067

Referenced by LookupBackgroundWorkerFunction().