PostgreSQL Source Code  git master
bgwriter.h File Reference
#include "storage/block.h"
#include "storage/relfilelocator.h"
#include "storage/smgr.h"
#include "storage/sync.h"
Include dependency graph for bgwriter.h:
This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Functions

void BackgroundWriterMain (void) pg_attribute_noreturn()
 
void CheckpointerMain (void) pg_attribute_noreturn()
 
void RequestCheckpoint (int flags)
 
void CheckpointWriteDelay (int flags, double progress)
 
bool ForwardSyncRequest (const FileTag *ftag, SyncRequestType type)
 
void AbsorbSyncRequests (void)
 
Size CheckpointerShmemSize (void)
 
void CheckpointerShmemInit (void)
 
bool FirstCallSinceLastCheckpoint (void)
 

Variables

PGDLLIMPORT int BgWriterDelay
 
PGDLLIMPORT int CheckPointTimeout
 
PGDLLIMPORT int CheckPointWarning
 
PGDLLIMPORT double CheckPointCompletionTarget
 

Function Documentation

◆ AbsorbSyncRequests()

void AbsorbSyncRequests ( void  )

Definition at line 1263 of file checkpointer.c.

1264 {
1265  CheckpointerRequest *requests = NULL;
1266  CheckpointerRequest *request;
1267  int n;
1268 
1269  if (!AmCheckpointerProcess())
1270  return;
1271 
1272  LWLockAcquire(CheckpointerCommLock, LW_EXCLUSIVE);
1273 
1274  /* Transfer stats counts into pending pgstats message */
1279 
1282 
1283  /*
1284  * We try to avoid holding the lock for a long time by copying the request
1285  * array, and processing the requests after releasing the lock.
1286  *
1287  * Once we have cleared the requests from shared memory, we have to PANIC
1288  * if we then fail to absorb them (eg, because our hashtable runs out of
1289  * memory). This is because the system cannot run safely if we are unable
1290  * to fsync what we have been told to fsync. Fortunately, the hashtable
1291  * is so small that the problem is quite unlikely to arise in practice.
1292  */
1294  if (n > 0)
1295  {
1296  requests = (CheckpointerRequest *) palloc(n * sizeof(CheckpointerRequest));
1297  memcpy(requests, CheckpointerShmem->requests, n * sizeof(CheckpointerRequest));
1298  }
1299 
1301 
1303 
1304  LWLockRelease(CheckpointerCommLock);
1305 
1306  for (request = requests; n > 0; request++, n--)
1307  RememberSyncRequest(&request->ftag, request->type);
1308 
1309  END_CRIT_SECTION();
1310 
1311  if (requests)
1312  pfree(requests);
1313 }
static CheckpointerShmemStruct * CheckpointerShmem
Definition: checkpointer.c:136
bool LWLockAcquire(LWLock *lock, LWLockMode mode)
Definition: lwlock.c:1194
void LWLockRelease(LWLock *lock)
Definition: lwlock.c:1802
@ LW_EXCLUSIVE
Definition: lwlock.h:112
void pfree(void *pointer)
Definition: mcxt.c:1306
void * palloc(Size size)
Definition: mcxt.c:1199
#define AmCheckpointerProcess()
Definition: miscadmin.h:443
#define START_CRIT_SECTION()
Definition: miscadmin.h:148
#define END_CRIT_SECTION()
Definition: miscadmin.h:150
PgStat_CheckpointerStats PendingCheckpointerStats
SyncRequestType type
Definition: checkpointer.c:109
CheckpointerRequest requests[FLEXIBLE_ARRAY_MEMBER]
Definition: checkpointer.c:133
PgStat_Counter buf_written_backend
Definition: pgstat.h:275
PgStat_Counter buf_fsync_backend
Definition: pgstat.h:276
void RememberSyncRequest(const FileTag *ftag, SyncRequestType type)
Definition: sync.c:494

References AmCheckpointerProcess, PgStat_CheckpointerStats::buf_fsync_backend, PgStat_CheckpointerStats::buf_written_backend, CheckpointerShmem, END_CRIT_SECTION, CheckpointerRequest::ftag, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), CheckpointerShmemStruct::num_backend_fsync, CheckpointerShmemStruct::num_backend_writes, CheckpointerShmemStruct::num_requests, palloc(), PendingCheckpointerStats, pfree(), RememberSyncRequest(), CheckpointerShmemStruct::requests, START_CRIT_SECTION, and CheckpointerRequest::type.

Referenced by CheckpointerMain(), CheckpointWriteDelay(), ProcessSyncRequests(), SyncPostCheckpoint(), and SyncPreCheckpoint().

◆ BackgroundWriterMain()

void BackgroundWriterMain ( void  )

Definition at line 91 of file bgwriter.c.

92 {
93  sigjmp_buf local_sigjmp_buf;
94  MemoryContext bgwriter_context;
95  bool prev_hibernate;
96  WritebackContext wb_context;
97 
98  /*
99  * Properly accept or ignore signals that might be sent to us.
100  */
102  pqsignal(SIGINT, SIG_IGN);
104  /* SIGQUIT handler was already set up by InitPostmasterChild */
109 
110  /*
111  * Reset some signals that are accepted by postmaster but not here
112  */
114 
115  /*
116  * We just started, assume there has been either a shutdown or
117  * end-of-recovery snapshot.
118  */
120 
121  /*
122  * Create a memory context that we will do all our work in. We do this so
123  * that we can reset the context during error recovery and thereby avoid
124  * possible memory leaks. Formerly this code just ran in
125  * TopMemoryContext, but resetting that would be a really bad idea.
126  */
127  bgwriter_context = AllocSetContextCreate(TopMemoryContext,
128  "Background Writer",
130  MemoryContextSwitchTo(bgwriter_context);
131 
133 
134  /*
135  * If an exception is encountered, processing resumes here.
136  *
137  * You might wonder why this isn't coded as an infinite loop around a
138  * PG_TRY construct. The reason is that this is the bottom of the
139  * exception stack, and so with PG_TRY there would be no exception handler
140  * in force at all during the CATCH part. By leaving the outermost setjmp
141  * always active, we have at least some chance of recovering from an error
142  * during error recovery. (If we get into an infinite loop thereby, it
143  * will soon be stopped by overflow of elog.c's internal state stack.)
144  *
145  * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
146  * (to wit, BlockSig) will be restored when longjmp'ing to here. Thus,
147  * signals other than SIGQUIT will be blocked until we complete error
148  * recovery. It might seem that this policy makes the HOLD_INTERRUPTS()
149  * call redundant, but it is not since InterruptPending might be set
150  * already.
151  */
152  if (sigsetjmp(local_sigjmp_buf, 1) != 0)
153  {
154  /* Since not using PG_TRY, must reset error stack by hand */
155  error_context_stack = NULL;
156 
157  /* Prevent interrupts while cleaning up */
158  HOLD_INTERRUPTS();
159 
160  /* Report the error to the server log */
161  EmitErrorReport();
162 
163  /*
164  * These operations are really just a minimal subset of
165  * AbortTransaction(). We don't have very many resources to worry
166  * about in bgwriter, but we do have LWLocks, buffers, and temp files.
167  */
170  AbortBufferIO();
171  UnlockBuffers();
173  AtEOXact_Buffers(false);
174  AtEOXact_SMgr();
175  AtEOXact_Files(false);
176  AtEOXact_HashTables(false);
177 
178  /*
179  * Now return to normal top-level context and clear ErrorContext for
180  * next time.
181  */
182  MemoryContextSwitchTo(bgwriter_context);
183  FlushErrorState();
184 
185  /* Flush any leaked data in the top-level context */
186  MemoryContextResetAndDeleteChildren(bgwriter_context);
187 
188  /* re-initialize to avoid repeated errors causing problems */
190 
191  /* Now we can allow interrupts again */
193 
194  /*
195  * Sleep at least 1 second after any error. A write error is likely
196  * to be repeated, and we don't want to be filling the error logs as
197  * fast as we can.
198  */
199  pg_usleep(1000000L);
200 
201  /*
202  * Close all open files after any error. This is helpful on Windows,
203  * where holding deleted files open causes various strange errors.
204  * It's not clear we need it elsewhere, but shouldn't hurt.
205  */
206  smgrcloseall();
207 
208  /* Report wait end here, when there is no further possibility of wait */
210  }
211 
212  /* We can now handle ereport(ERROR) */
213  PG_exception_stack = &local_sigjmp_buf;
214 
215  /*
216  * Unblock signals (they were blocked when the postmaster forked us)
217  */
219 
220  /*
221  * Reset hibernation state after any error.
222  */
223  prev_hibernate = false;
224 
225  /*
226  * Loop forever
227  */
228  for (;;)
229  {
230  bool can_hibernate;
231  int rc;
232 
233  /* Clear any already-pending wakeups */
235 
237 
238  /*
239  * Do one cycle of dirty-buffer writing.
240  */
241  can_hibernate = BgBufferSync(&wb_context);
242 
243  /* Report pending statistics to the cumulative stats system */
245 
247  {
248  /*
249  * After any checkpoint, close all smgr files. This is so we
250  * won't hang onto smgr references to deleted files indefinitely.
251  */
252  smgrcloseall();
253  }
254 
255  /*
256  * Log a new xl_running_xacts every now and then so replication can
257  * get into a consistent state faster (think of suboverflowed
258  * snapshots) and clean up resources (locks, KnownXids*) more
259  * frequently. The costs of this are relatively low, so doing it 4
260  * times (LOG_SNAPSHOT_INTERVAL_MS) a minute seems fine.
261  *
262  * We assume the interval for writing xl_running_xacts is
263  * significantly bigger than BgWriterDelay, so we don't complicate the
264  * overall timeout handling but just assume we're going to get called
265  * often enough even if hibernation mode is active. It's not that
266  * important that LOG_SNAPSHOT_INTERVAL_MS is met strictly. To make
267  * sure we're not waking the disk up unnecessarily on an idle system
268  * we check whether there has been any WAL inserted since the last
269  * time we've logged a running xacts.
270  *
271  * We do this logging in the bgwriter as it is the only process that
272  * is run regularly and returns to its mainloop all the time. E.g.
273  * Checkpointer, when active, is barely ever in its mainloop and thus
274  * makes it hard to log regularly.
275  */
277  {
278  TimestampTz timeout = 0;
280 
283 
284  /*
285  * Only log if enough time has passed and interesting records have
286  * been inserted since the last snapshot. Have to compare with <=
287  * instead of < because GetLastImportantRecPtr() points at the
288  * start of a record, whereas last_snapshot_lsn points just past
289  * the end of the record.
290  */
291  if (now >= timeout &&
293  {
296  }
297  }
298 
299  /*
300  * Sleep until we are signaled or BgWriterDelay has elapsed.
301  *
302  * Note: the feedback control loop in BgBufferSync() expects that we
303  * will call it every BgWriterDelay msec. While it's not critical for
304  * correctness that that be exact, the feedback loop might misbehave
305  * if we stray too far from that. Hence, avoid loading this process
306  * down with latch events that are likely to happen frequently during
307  * normal operation.
308  */
309  rc = WaitLatch(MyLatch,
312 
313  /*
314  * If no latch event and BgBufferSync says nothing's happening, extend
315  * the sleep in "hibernation" mode, where we sleep for much longer
316  * than bgwriter_delay says. Fewer wakeups save electricity. When a
317  * backend starts using buffers again, it will wake us up by setting
318  * our latch. Because the extra sleep will persist only as long as no
319  * buffer allocations happen, this should not distort the behavior of
320  * BgBufferSync's control loop too badly; essentially, it will think
321  * that the system-wide idle interval didn't exist.
322  *
323  * There is a race condition here, in that a backend might allocate a
324  * buffer between the time BgBufferSync saw the alloc count as zero
325  * and the time we call StrategyNotifyBgWriter. While it's not
326  * critical that we not hibernate anyway, we try to reduce the odds of
327  * that by only hibernating when BgBufferSync says nothing's happening
328  * for two consecutive cycles. Also, we mitigate any possible
329  * consequences of a missed wakeup by not hibernating forever.
330  */
331  if (rc == WL_TIMEOUT && can_hibernate && prev_hibernate)
332  {
333  /* Ask for notification at next buffer allocation */
335  /* Sleep ... */
336  (void) WaitLatch(MyLatch,
340  /* Reset the notification request in case we timed out */
342  }
343 
344  prev_hibernate = can_hibernate;
345  }
346 }
sigset_t UnBlockSig
Definition: pqsignal.c:22
TimestampTz GetCurrentTimestamp(void)
Definition: timestamp.c:1573
Datum now(PG_FUNCTION_ARGS)
Definition: timestamp.c:1537
static XLogRecPtr last_snapshot_lsn
Definition: bgwriter.c:81
static TimestampTz last_snapshot_ts
Definition: bgwriter.c:80
int BgWriterDelay
Definition: bgwriter.c:61
#define HIBERNATE_FACTOR
Definition: bgwriter.c:67
#define LOG_SNAPSHOT_INTERVAL_MS
Definition: bgwriter.c:73
void AtEOXact_Buffers(bool isCommit)
Definition: bufmgr.c:2594
bool BgBufferSync(WritebackContext *wb_context)
Definition: bufmgr.c:2224
void UnlockBuffers(void)
Definition: bufmgr.c:4144
int bgwriter_flush_after
Definition: bufmgr.c:159
void WritebackContextInit(WritebackContext *context, int *max_pending)
Definition: bufmgr.c:4895
void AbortBufferIO(void)
Definition: bufmgr.c:4642
bool FirstCallSinceLastCheckpoint(void)
void ConditionVariableCancelSleep(void)
int64 TimestampTz
Definition: timestamp.h:39
void AtEOXact_HashTables(bool isCommit)
Definition: dynahash.c:1878
void EmitErrorReport(void)
Definition: elog.c:1546
ErrorContextCallback * error_context_stack
Definition: elog.c:94
void FlushErrorState(void)
Definition: elog.c:1702
sigjmp_buf * PG_exception_stack
Definition: elog.c:96
void AtEOXact_Files(bool isCommit)
Definition: fd.c:2965
void StrategyNotifyBgWriter(int bgwprocno)
Definition: freelist.c:431
struct Latch * MyLatch
Definition: globals.c:58
void SignalHandlerForShutdownRequest(SIGNAL_ARGS)
Definition: interrupt.c:108
void SignalHandlerForConfigReload(SIGNAL_ARGS)
Definition: interrupt.c:61
void HandleMainLoopInterrupts(void)
Definition: interrupt.c:34
void ResetLatch(Latch *latch)
Definition: latch.c:683
int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info)
Definition: latch.c:476
#define WL_TIMEOUT
Definition: latch.h:128
#define WL_EXIT_ON_PM_DEATH
Definition: latch.h:130
#define WL_LATCH_SET
Definition: latch.h:125
void LWLockReleaseAll(void)
Definition: lwlock.c:1901
MemoryContext TopMemoryContext
Definition: mcxt.c:130
#define AllocSetContextCreate
Definition: memutils.h:129
#define ALLOCSET_DEFAULT_SIZES
Definition: memutils.h:153
#define MemoryContextResetAndDeleteChildren(ctx)
Definition: memutils.h:70
#define RESUME_INTERRUPTS()
Definition: miscadmin.h:134
#define HOLD_INTERRUPTS()
Definition: miscadmin.h:132
static MemoryContext MemoryContextSwitchTo(MemoryContext context)
Definition: palloc.h:135
void pgstat_report_bgwriter(void)
pqsigfunc pqsignal(int signo, pqsigfunc func)
#define PG_SETMASK(mask)
Definition: pqsignal.h:18
void procsignal_sigusr1_handler(SIGNAL_ARGS)
Definition: procsignal.c:638
void ReleaseAuxProcessResources(bool isCommit)
Definition: resowner.c:912
void pg_usleep(long microsec)
Definition: signal.c:53
void smgrcloseall(void)
Definition: smgr.c:322
void AtEOXact_SMgr(void)
Definition: smgr.c:709
PGPROC * MyProc
Definition: proc.c:68
XLogRecPtr LogStandbySnapshot(void)
Definition: standby.c:1272
int pgprocno
Definition: proc.h:191
#define TimestampTzPlusMilliseconds(tz, ms)
Definition: timestamp.h:84
@ WAIT_EVENT_BGWRITER_MAIN
Definition: wait_event.h:41
@ WAIT_EVENT_BGWRITER_HIBERNATE
Definition: wait_event.h:40
static void pgstat_report_wait_end(void)
Definition: wait_event.h:284
#define SIGCHLD
Definition: win32_port.h:186
#define SIGHUP
Definition: win32_port.h:176
#define SIG_DFL
Definition: win32_port.h:171
#define SIGPIPE
Definition: win32_port.h:181
#define SIGUSR1
Definition: win32_port.h:188
#define SIGALRM
Definition: win32_port.h:182
#define SIGUSR2
Definition: win32_port.h:189
#define SIG_IGN
Definition: win32_port.h:173
bool RecoveryInProgress(void)
Definition: xlog.c:5912
XLogRecPtr GetLastImportantRecPtr(void)
Definition: xlog.c:6117
#define XLogStandbyInfoActive()
Definition: xlog.h:118

References AbortBufferIO(), ALLOCSET_DEFAULT_SIZES, AllocSetContextCreate, AtEOXact_Buffers(), AtEOXact_Files(), AtEOXact_HashTables(), AtEOXact_SMgr(), BgBufferSync(), bgwriter_flush_after, BgWriterDelay, ConditionVariableCancelSleep(), EmitErrorReport(), error_context_stack, FirstCallSinceLastCheckpoint(), FlushErrorState(), GetCurrentTimestamp(), GetLastImportantRecPtr(), HandleMainLoopInterrupts(), HIBERNATE_FACTOR, HOLD_INTERRUPTS, last_snapshot_lsn, last_snapshot_ts, LOG_SNAPSHOT_INTERVAL_MS, LogStandbySnapshot(), LWLockReleaseAll(), MemoryContextResetAndDeleteChildren, MemoryContextSwitchTo(), MyLatch, MyProc, now(), PG_exception_stack, PG_SETMASK, pg_usleep(), PGPROC::pgprocno, pgstat_report_bgwriter(), pgstat_report_wait_end(), pqsignal(), procsignal_sigusr1_handler(), RecoveryInProgress(), ReleaseAuxProcessResources(), ResetLatch(), RESUME_INTERRUPTS, SIG_DFL, SIG_IGN, SIGALRM, SIGCHLD, SIGHUP, SignalHandlerForConfigReload(), SignalHandlerForShutdownRequest(), SIGPIPE, SIGUSR1, SIGUSR2, smgrcloseall(), StrategyNotifyBgWriter(), TimestampTzPlusMilliseconds, TopMemoryContext, UnBlockSig, UnlockBuffers(), WAIT_EVENT_BGWRITER_HIBERNATE, WAIT_EVENT_BGWRITER_MAIN, WaitLatch(), WL_EXIT_ON_PM_DEATH, WL_LATCH_SET, WL_TIMEOUT, WritebackContextInit(), and XLogStandbyInfoActive.

Referenced by AuxiliaryProcessMain().

◆ CheckpointerMain()

void CheckpointerMain ( void  )

Definition at line 181 of file checkpointer.c.

182 {
183  sigjmp_buf local_sigjmp_buf;
184  MemoryContext checkpointer_context;
185 
187 
188  /*
189  * Properly accept or ignore signals the postmaster might send us
190  *
191  * Note: we deliberately ignore SIGTERM, because during a standard Unix
192  * system shutdown cycle, init will SIGTERM all processes at once. We
193  * want to wait for the backends to exit, whereupon the postmaster will
194  * tell us it's okay to shut down (via SIGUSR2).
195  */
197  pqsignal(SIGINT, ReqCheckpointHandler); /* request checkpoint */
198  pqsignal(SIGTERM, SIG_IGN); /* ignore SIGTERM */
199  /* SIGQUIT handler was already set up by InitPostmasterChild */
204 
205  /*
206  * Reset some signals that are accepted by postmaster but not here
207  */
209 
210  /*
211  * Initialize so that first time-driven event happens at the correct time.
212  */
214 
215  /*
216  * Write out stats after shutdown. This needs to be called by exactly one
217  * process during a normal shutdown, and since checkpointer is shut down
218  * very late...
219  *
220  * Walsenders are shut down after the checkpointer, but currently don't
221  * report stats. If that changes, we need a more complicated solution.
222  */
224 
225  /*
226  * Create a memory context that we will do all our work in. We do this so
227  * that we can reset the context during error recovery and thereby avoid
228  * possible memory leaks. Formerly this code just ran in
229  * TopMemoryContext, but resetting that would be a really bad idea.
230  */
231  checkpointer_context = AllocSetContextCreate(TopMemoryContext,
232  "Checkpointer",
234  MemoryContextSwitchTo(checkpointer_context);
235 
236  /*
237  * If an exception is encountered, processing resumes here.
238  *
239  * You might wonder why this isn't coded as an infinite loop around a
240  * PG_TRY construct. The reason is that this is the bottom of the
241  * exception stack, and so with PG_TRY there would be no exception handler
242  * in force at all during the CATCH part. By leaving the outermost setjmp
243  * always active, we have at least some chance of recovering from an error
244  * during error recovery. (If we get into an infinite loop thereby, it
245  * will soon be stopped by overflow of elog.c's internal state stack.)
246  *
247  * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
248  * (to wit, BlockSig) will be restored when longjmp'ing to here. Thus,
249  * signals other than SIGQUIT will be blocked until we complete error
250  * recovery. It might seem that this policy makes the HOLD_INTERRUPTS()
251  * call redundant, but it is not since InterruptPending might be set
252  * already.
253  */
254  if (sigsetjmp(local_sigjmp_buf, 1) != 0)
255  {
256  /* Since not using PG_TRY, must reset error stack by hand */
257  error_context_stack = NULL;
258 
259  /* Prevent interrupts while cleaning up */
260  HOLD_INTERRUPTS();
261 
262  /* Report the error to the server log */
263  EmitErrorReport();
264 
265  /*
266  * These operations are really just a minimal subset of
267  * AbortTransaction(). We don't have very many resources to worry
268  * about in checkpointer, but we do have LWLocks, buffers, and temp
269  * files.
270  */
274  AbortBufferIO();
275  UnlockBuffers();
277  AtEOXact_Buffers(false);
278  AtEOXact_SMgr();
279  AtEOXact_Files(false);
280  AtEOXact_HashTables(false);
281 
282  /* Warn any waiting backends that the checkpoint failed. */
283  if (ckpt_active)
284  {
289 
291 
292  ckpt_active = false;
293  }
294 
295  /*
296  * Now return to normal top-level context and clear ErrorContext for
297  * next time.
298  */
299  MemoryContextSwitchTo(checkpointer_context);
300  FlushErrorState();
301 
302  /* Flush any leaked data in the top-level context */
303  MemoryContextResetAndDeleteChildren(checkpointer_context);
304 
305  /* Now we can allow interrupts again */
307 
308  /*
309  * Sleep at least 1 second after any error. A write error is likely
310  * to be repeated, and we don't want to be filling the error logs as
311  * fast as we can.
312  */
313  pg_usleep(1000000L);
314 
315  /*
316  * Close all open files after any error. This is helpful on Windows,
317  * where holding deleted files open causes various strange errors.
318  * It's not clear we need it elsewhere, but shouldn't hurt.
319  */
320  smgrcloseall();
321  }
322 
323  /* We can now handle ereport(ERROR) */
324  PG_exception_stack = &local_sigjmp_buf;
325 
326  /*
327  * Unblock signals (they were blocked when the postmaster forked us)
328  */
330 
331  /*
332  * Ensure all shared memory values are set correctly for the config. Doing
333  * this here ensures no race conditions from other concurrent updaters.
334  */
336 
337  /*
338  * Advertise our latch that backends can use to wake us up while we're
339  * sleeping.
340  */
342 
343  /*
344  * Loop forever
345  */
346  for (;;)
347  {
348  bool do_checkpoint = false;
349  int flags = 0;
350  pg_time_t now;
351  int elapsed_secs;
352  int cur_timeout;
353 
354  /* Clear any already-pending wakeups */
356 
357  /*
358  * Process any requests or signals received recently.
359  */
362 
363  /*
364  * Detect a pending checkpoint request by checking whether the flags
365  * word in shared memory is nonzero. We shouldn't need to acquire the
366  * ckpt_lck for this.
367  */
368  if (((volatile CheckpointerShmemStruct *) CheckpointerShmem)->ckpt_flags)
369  {
370  do_checkpoint = true;
372  }
373 
374  /*
375  * Force a checkpoint if too much time has elapsed since the last one.
376  * Note that we count a timed checkpoint in stats only when this
377  * occurs without an external request, but we set the CAUSE_TIME flag
378  * bit even if there is also an external request.
379  */
380  now = (pg_time_t) time(NULL);
381  elapsed_secs = now - last_checkpoint_time;
382  if (elapsed_secs >= CheckPointTimeout)
383  {
384  if (!do_checkpoint)
386  do_checkpoint = true;
387  flags |= CHECKPOINT_CAUSE_TIME;
388  }
389 
390  /*
391  * Do a checkpoint if requested.
392  */
393  if (do_checkpoint)
394  {
395  bool ckpt_performed = false;
396  bool do_restartpoint;
397 
398  /* Check if we should perform a checkpoint or a restartpoint. */
399  do_restartpoint = RecoveryInProgress();
400 
401  /*
402  * Atomically fetch the request flags to figure out what kind of a
403  * checkpoint we should perform, and increase the started-counter
404  * to acknowledge that we've started a new checkpoint.
405  */
407  flags |= CheckpointerShmem->ckpt_flags;
411 
413 
414  /*
415  * The end-of-recovery checkpoint is a real checkpoint that's
416  * performed while we're still in recovery.
417  */
418  if (flags & CHECKPOINT_END_OF_RECOVERY)
419  do_restartpoint = false;
420 
421  /*
422  * We will warn if (a) too soon since last checkpoint (whatever
423  * caused it) and (b) somebody set the CHECKPOINT_CAUSE_XLOG flag
424  * since the last checkpoint start. Note in particular that this
425  * implementation will not generate warnings caused by
426  * CheckPointTimeout < CheckPointWarning.
427  */
428  if (!do_restartpoint &&
429  (flags & CHECKPOINT_CAUSE_XLOG) &&
430  elapsed_secs < CheckPointWarning)
431  ereport(LOG,
432  (errmsg_plural("checkpoints are occurring too frequently (%d second apart)",
433  "checkpoints are occurring too frequently (%d seconds apart)",
434  elapsed_secs,
435  elapsed_secs),
436  errhint("Consider increasing the configuration parameter \"max_wal_size\".")));
437 
438  /*
439  * Initialize checkpointer-private variables used during
440  * checkpoint.
441  */
442  ckpt_active = true;
443  if (do_restartpoint)
445  else
449 
450  /*
451  * Do the checkpoint.
452  */
453  if (!do_restartpoint)
454  {
455  CreateCheckPoint(flags);
456  ckpt_performed = true;
457  }
458  else
459  ckpt_performed = CreateRestartPoint(flags);
460 
461  /*
462  * After any checkpoint, close all smgr files. This is so we
463  * won't hang onto smgr references to deleted files indefinitely.
464  */
465  smgrcloseall();
466 
467  /*
468  * Indicate checkpoint completion to any waiting backends.
469  */
473 
475 
476  if (ckpt_performed)
477  {
478  /*
479  * Note we record the checkpoint start time not end time as
480  * last_checkpoint_time. This is so that time-driven
481  * checkpoints happen at a predictable spacing.
482  */
484  }
485  else
486  {
487  /*
488  * We were not able to perform the restartpoint (checkpoints
489  * throw an ERROR in case of error). Most likely because we
490  * have not received any new checkpoint WAL records since the
491  * last restartpoint. Try again in 15 s.
492  */
494  }
495 
496  ckpt_active = false;
497 
498  /* We may have received an interrupt during the checkpoint. */
500  }
501 
502  /* Check for archive_timeout and switch xlog files if necessary. */
504 
505  /* Report pending statistics to the cumulative stats system */
507  pgstat_report_wal(true);
508 
509  /*
510  * If any checkpoint flags have been set, redo the loop to handle the
511  * checkpoint without sleeping.
512  */
513  if (((volatile CheckpointerShmemStruct *) CheckpointerShmem)->ckpt_flags)
514  continue;
515 
516  /*
517  * Sleep until we are signaled or it's time for another checkpoint or
518  * xlog file switch.
519  */
520  now = (pg_time_t) time(NULL);
521  elapsed_secs = now - last_checkpoint_time;
522  if (elapsed_secs >= CheckPointTimeout)
523  continue; /* no sleep for us ... */
524  cur_timeout = CheckPointTimeout - elapsed_secs;
526  {
527  elapsed_secs = now - last_xlog_switch_time;
528  if (elapsed_secs >= XLogArchiveTimeout)
529  continue; /* no sleep for us ... */
530  cur_timeout = Min(cur_timeout, XLogArchiveTimeout - elapsed_secs);
531  }
532 
533  (void) WaitLatch(MyLatch,
535  cur_timeout * 1000L /* convert to ms */ ,
537  }
538 }
#define Min(x, y)
Definition: c.h:937
static void UpdateSharedMemoryConfig(void)
static XLogRecPtr ckpt_start_recptr
Definition: checkpointer.c:155
static void ReqCheckpointHandler(SIGNAL_ARGS)
Definition: checkpointer.c:845
static void CheckArchiveTimeout(void)
Definition: checkpointer.c:609
static double ckpt_cached_elapsed
Definition: checkpointer.c:156
static bool ckpt_active
Definition: checkpointer.c:151
static void HandleCheckpointerInterrupts(void)
Definition: checkpointer.c:544
void AbsorbSyncRequests(void)
static pg_time_t last_xlog_switch_time
Definition: checkpointer.c:159
int CheckPointWarning
Definition: checkpointer.c:145
int CheckPointTimeout
Definition: checkpointer.c:144
static pg_time_t last_checkpoint_time
Definition: checkpointer.c:158
static pg_time_t ckpt_start_time
Definition: checkpointer.c:154
void ConditionVariableBroadcast(ConditionVariable *cv)
int errmsg_plural(const char *fmt_singular, const char *fmt_plural, unsigned long n,...)
Definition: elog.c:1056
int errhint(const char *fmt,...)
Definition: elog.c:1193
#define LOG
Definition: elog.h:27
#define ereport(elevel,...)
Definition: elog.h:145
int MyProcPid
Definition: globals.c:44
void before_shmem_exit(pg_on_exit_callback function, Datum arg)
Definition: ipc.c:333
void pgstat_before_server_shutdown(int code, Datum arg)
Definition: pgstat.c:448
void pgstat_report_checkpointer(void)
void pgstat_report_wal(bool force)
Definition: pgstat_wal.c:43
int64 pg_time_t
Definition: pgtime.h:23
#define SpinLockRelease(lock)
Definition: spin.h:64
#define SpinLockAcquire(lock)
Definition: spin.h:62
PROC_HDR * ProcGlobal
Definition: proc.c:80
ConditionVariable done_cv
Definition: checkpointer.c:126
ConditionVariable start_cv
Definition: checkpointer.c:125
Latch procLatch
Definition: proc.h:170
Latch * checkpointerLatch
Definition: proc.h:396
PgStat_Counter requested_checkpoints
Definition: pgstat.h:271
PgStat_Counter timed_checkpoints
Definition: pgstat.h:270
@ WAIT_EVENT_CHECKPOINTER_MAIN
Definition: wait_event.h:42
bool CreateRestartPoint(int flags)
Definition: xlog.c:7081
XLogRecPtr GetInsertRecPtr(void)
Definition: xlog.c:6060
int XLogArchiveTimeout
Definition: xlog.c:121
void CreateCheckPoint(int flags)
Definition: xlog.c:6440
#define CHECKPOINT_CAUSE_XLOG
Definition: xlog.h:143
#define CHECKPOINT_END_OF_RECOVERY
Definition: xlog.h:135
#define CHECKPOINT_CAUSE_TIME
Definition: xlog.h:144
XLogRecPtr GetXLogReplayRecPtr(TimeLineID *replayTLI)

References AbortBufferIO(), AbsorbSyncRequests(), ALLOCSET_DEFAULT_SIZES, AllocSetContextCreate, AtEOXact_Buffers(), AtEOXact_Files(), AtEOXact_HashTables(), AtEOXact_SMgr(), before_shmem_exit(), CheckArchiveTimeout(), CHECKPOINT_CAUSE_TIME, CHECKPOINT_CAUSE_XLOG, CHECKPOINT_END_OF_RECOVERY, CheckpointerShmemStruct::checkpointer_pid, PROC_HDR::checkpointerLatch, CheckpointerShmem, CheckPointTimeout, CheckPointWarning, ckpt_active, ckpt_cached_elapsed, CheckpointerShmemStruct::ckpt_done, CheckpointerShmemStruct::ckpt_failed, CheckpointerShmemStruct::ckpt_flags, CheckpointerShmemStruct::ckpt_lck, ckpt_start_recptr, ckpt_start_time, CheckpointerShmemStruct::ckpt_started, ConditionVariableBroadcast(), ConditionVariableCancelSleep(), CreateCheckPoint(), CreateRestartPoint(), CheckpointerShmemStruct::done_cv, EmitErrorReport(), ereport, errhint(), errmsg_plural(), error_context_stack, FlushErrorState(), GetInsertRecPtr(), GetXLogReplayRecPtr(), HandleCheckpointerInterrupts(), HOLD_INTERRUPTS, last_checkpoint_time, last_xlog_switch_time, LOG, LWLockReleaseAll(), MemoryContextResetAndDeleteChildren, MemoryContextSwitchTo(), Min, MyLatch, MyProc, MyProcPid, now(), PendingCheckpointerStats, PG_exception_stack, PG_SETMASK, pg_usleep(), pgstat_before_server_shutdown(), pgstat_report_checkpointer(), pgstat_report_wait_end(), pgstat_report_wal(), pqsignal(), ProcGlobal, PGPROC::procLatch, procsignal_sigusr1_handler(), RecoveryInProgress(), ReleaseAuxProcessResources(), ReqCheckpointHandler(), PgStat_CheckpointerStats::requested_checkpoints, ResetLatch(), RESUME_INTERRUPTS, SIG_DFL, SIG_IGN, SIGALRM, SIGCHLD, SIGHUP, SignalHandlerForConfigReload(), SignalHandlerForShutdownRequest(), SIGPIPE, SIGUSR1, SIGUSR2, smgrcloseall(), SpinLockAcquire, SpinLockRelease, CheckpointerShmemStruct::start_cv, PgStat_CheckpointerStats::timed_checkpoints, TopMemoryContext, UnBlockSig, UnlockBuffers(), UpdateSharedMemoryConfig(), WAIT_EVENT_CHECKPOINTER_MAIN, WaitLatch(), WL_EXIT_ON_PM_DEATH, WL_LATCH_SET, WL_TIMEOUT, and XLogArchiveTimeout.

Referenced by AuxiliaryProcessMain().

◆ CheckpointerShmemInit()

void CheckpointerShmemInit ( void  )

Definition at line 888 of file checkpointer.c.

889 {
890  Size size = CheckpointerShmemSize();
891  bool found;
892 
894  ShmemInitStruct("Checkpointer Data",
895  size,
896  &found);
897 
898  if (!found)
899  {
900  /*
901  * First time through, so initialize. Note that we zero the whole
902  * requests array; this is so that CompactCheckpointerRequestQueue can
903  * assume that any pad bytes in the request structs are zeroes.
904  */
905  MemSet(CheckpointerShmem, 0, size);
910  }
911 }
#define MemSet(start, val, len)
Definition: c.h:953
size_t Size
Definition: c.h:541
Size CheckpointerShmemSize(void)
Definition: checkpointer.c:869
void ConditionVariableInit(ConditionVariable *cv)
int NBuffers
Definition: globals.c:136
void * ShmemInitStruct(const char *name, Size size, bool *foundPtr)
Definition: shmem.c:396
#define SpinLockInit(lock)
Definition: spin.h:60

References CheckpointerShmem, CheckpointerShmemSize(), CheckpointerShmemStruct::ckpt_lck, ConditionVariableInit(), CheckpointerShmemStruct::done_cv, CheckpointerShmemStruct::max_requests, MemSet, NBuffers, ShmemInitStruct(), SpinLockInit, and CheckpointerShmemStruct::start_cv.

Referenced by CreateSharedMemoryAndSemaphores().

◆ CheckpointerShmemSize()

Size CheckpointerShmemSize ( void  )

Definition at line 869 of file checkpointer.c.

870 {
871  Size size;
872 
873  /*
874  * Currently, the size of the requests[] array is arbitrarily set equal to
875  * NBuffers. This may prove too large or small ...
876  */
877  size = offsetof(CheckpointerShmemStruct, requests);
878  size = add_size(size, mul_size(NBuffers, sizeof(CheckpointerRequest)));
879 
880  return size;
881 }
Size add_size(Size s1, Size s2)
Definition: shmem.c:502
Size mul_size(Size s1, Size s2)
Definition: shmem.c:519

References add_size(), mul_size(), and NBuffers.

Referenced by CalculateShmemSize(), and CheckpointerShmemInit().

◆ CheckpointWriteDelay()

void CheckpointWriteDelay ( int  flags,
double  progress 
)

Definition at line 697 of file checkpointer.c.

698 {
699  static int absorb_counter = WRITES_PER_ABSORB;
700 
701  /* Do nothing if checkpoint is being executed by non-checkpointer process */
702  if (!AmCheckpointerProcess())
703  return;
704 
705  /*
706  * Perform the usual duties and take a nap, unless we're behind schedule,
707  * in which case we just try to catch up as quickly as possible.
708  */
709  if (!(flags & CHECKPOINT_IMMEDIATE) &&
713  {
715  {
716  ConfigReloadPending = false;
718  /* update shmem copies of config variables */
720  }
721 
723  absorb_counter = WRITES_PER_ABSORB;
724 
726 
727  /* Report interim statistics to the cumulative stats system */
729 
730  /*
731  * This sleep used to be connected to bgwriter_delay, typically 200ms.
732  * That resulted in more frequent wakeups if not much work to do.
733  * Checkpointer and bgwriter are no longer related so take the Big
734  * Sleep.
735  */
737  100,
740  }
741  else if (--absorb_counter <= 0)
742  {
743  /*
744  * Absorb pending fsync requests after each WRITES_PER_ABSORB write
745  * operations even when we don't sleep, to prevent overflow of the
746  * fsync request queue.
747  */
749  absorb_counter = WRITES_PER_ABSORB;
750  }
751 
752  /* Check for barrier events. */
755 }
static bool ImmediateCheckpointRequested(void)
Definition: checkpointer.c:670
static bool IsCheckpointOnSchedule(double progress)
Definition: checkpointer.c:766
#define WRITES_PER_ABSORB
Definition: checkpointer.c:139
volatile sig_atomic_t ProcSignalBarrierPending
Definition: globals.c:37
@ PGC_SIGHUP
Definition: guc.h:71
void ProcessConfigFile(GucContext context)
volatile sig_atomic_t ShutdownRequestPending
Definition: interrupt.c:28
volatile sig_atomic_t ConfigReloadPending
Definition: interrupt.c:27
int progress
Definition: pgbench.c:270
void ProcessProcSignalBarrier(void)
Definition: procsignal.c:467
@ WAIT_EVENT_CHECKPOINT_WRITE_DELAY
Definition: wait_event.h:143
#define CHECKPOINT_IMMEDIATE
Definition: xlog.h:136

References AbsorbSyncRequests(), AmCheckpointerProcess, CheckArchiveTimeout(), CHECKPOINT_IMMEDIATE, ConfigReloadPending, ImmediateCheckpointRequested(), IsCheckpointOnSchedule(), MyLatch, PGC_SIGHUP, pgstat_report_checkpointer(), ProcessConfigFile(), ProcessProcSignalBarrier(), ProcSignalBarrierPending, progress, ResetLatch(), ShutdownRequestPending, UpdateSharedMemoryConfig(), WAIT_EVENT_CHECKPOINT_WRITE_DELAY, WaitLatch(), WL_EXIT_ON_PM_DEATH, WL_LATCH_SET, WL_TIMEOUT, and WRITES_PER_ABSORB.

Referenced by BufferSync().

◆ FirstCallSinceLastCheckpoint()

bool FirstCallSinceLastCheckpoint ( void  )

Definition at line 1338 of file checkpointer.c.

1339 {
1340  static int ckpt_done = 0;
1341  int new_done;
1342  bool FirstCall = false;
1343 
1345  new_done = CheckpointerShmem->ckpt_done;
1347 
1348  if (new_done != ckpt_done)
1349  FirstCall = true;
1350 
1351  ckpt_done = new_done;
1352 
1353  return FirstCall;
1354 }

References CheckpointerShmem, CheckpointerShmemStruct::ckpt_done, CheckpointerShmemStruct::ckpt_lck, SpinLockAcquire, and SpinLockRelease.

Referenced by BackgroundWriterMain().

◆ ForwardSyncRequest()

bool ForwardSyncRequest ( const FileTag ftag,
SyncRequestType  type 
)

Definition at line 1086 of file checkpointer.c.

1087 {
1088  CheckpointerRequest *request;
1089  bool too_full;
1090 
1091  if (!IsUnderPostmaster)
1092  return false; /* probably shouldn't even get here */
1093 
1094  if (AmCheckpointerProcess())
1095  elog(ERROR, "ForwardSyncRequest must not be called in checkpointer");
1096 
1097  LWLockAcquire(CheckpointerCommLock, LW_EXCLUSIVE);
1098 
1099  /* Count all backend writes regardless of if they fit in the queue */
1102 
1103  /*
1104  * If the checkpointer isn't running or the request queue is full, the
1105  * backend will have to perform its own fsync request. But before forcing
1106  * that to happen, we can try to compact the request queue.
1107  */
1108  if (CheckpointerShmem->checkpointer_pid == 0 ||
1111  {
1112  /*
1113  * Count the subset of writes where backends have to do their own
1114  * fsync
1115  */
1118  LWLockRelease(CheckpointerCommLock);
1119  return false;
1120  }
1121 
1122  /* OK, insert request */
1124  request->ftag = *ftag;
1125  request->type = type;
1126 
1127  /* If queue is more than half full, nudge the checkpointer to empty it */
1128  too_full = (CheckpointerShmem->num_requests >=
1130 
1131  LWLockRelease(CheckpointerCommLock);
1132 
1133  /* ... but not till after we release the lock */
1134  if (too_full && ProcGlobal->checkpointerLatch)
1136 
1137  return true;
1138 }
static bool CompactCheckpointerRequestQueue(void)
#define ERROR
Definition: elog.h:35
bool IsUnderPostmaster
Definition: globals.c:113
void SetLatch(Latch *latch)
Definition: latch.c:591
#define AmBackgroundWriterProcess()
Definition: miscadmin.h:441

References AmBackgroundWriterProcess, AmCheckpointerProcess, CheckpointerShmemStruct::checkpointer_pid, PROC_HDR::checkpointerLatch, CheckpointerShmem, CompactCheckpointerRequestQueue(), elog(), ERROR, CheckpointerRequest::ftag, IsUnderPostmaster, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), CheckpointerShmemStruct::max_requests, CheckpointerShmemStruct::num_backend_fsync, CheckpointerShmemStruct::num_backend_writes, CheckpointerShmemStruct::num_requests, ProcGlobal, CheckpointerShmemStruct::requests, SetLatch(), generate_unaccent_rules::type, and CheckpointerRequest::type.

Referenced by RegisterSyncRequest().

◆ RequestCheckpoint()

void RequestCheckpoint ( int  flags)

Definition at line 931 of file checkpointer.c.

932 {
933  int ntries;
934  int old_failed,
935  old_started;
936 
937  /*
938  * If in a standalone backend, just do it ourselves.
939  */
941  {
942  /*
943  * There's no point in doing slow checkpoints in a standalone backend,
944  * because there's no other backends the checkpoint could disrupt.
945  */
947 
948  /*
949  * After any checkpoint, close all smgr files. This is so we won't
950  * hang onto smgr references to deleted files indefinitely.
951  */
952  smgrcloseall();
953 
954  return;
955  }
956 
957  /*
958  * Atomically set the request flags, and take a snapshot of the counters.
959  * When we see ckpt_started > old_started, we know the flags we set here
960  * have been seen by checkpointer.
961  *
962  * Note that we OR the flags with any existing flags, to avoid overriding
963  * a "stronger" request by another backend. The flag senses must be
964  * chosen to make this work!
965  */
967 
968  old_failed = CheckpointerShmem->ckpt_failed;
969  old_started = CheckpointerShmem->ckpt_started;
971 
973 
974  /*
975  * Send signal to request checkpoint. It's possible that the checkpointer
976  * hasn't started yet, or is in process of restarting, so we will retry a
977  * few times if needed. (Actually, more than a few times, since on slow
978  * or overloaded buildfarm machines, it's been observed that the
979  * checkpointer can take several seconds to start.) However, if not told
980  * to wait for the checkpoint to occur, we consider failure to send the
981  * signal to be nonfatal and merely LOG it. The checkpointer should see
982  * the request when it does start, with or without getting a signal.
983  */
984 #define MAX_SIGNAL_TRIES 600 /* max wait 60.0 sec */
985  for (ntries = 0;; ntries++)
986  {
988  {
989  if (ntries >= MAX_SIGNAL_TRIES || !(flags & CHECKPOINT_WAIT))
990  {
991  elog((flags & CHECKPOINT_WAIT) ? ERROR : LOG,
992  "could not signal for checkpoint: checkpointer is not running");
993  break;
994  }
995  }
996  else if (kill(CheckpointerShmem->checkpointer_pid, SIGINT) != 0)
997  {
998  if (ntries >= MAX_SIGNAL_TRIES || !(flags & CHECKPOINT_WAIT))
999  {
1000  elog((flags & CHECKPOINT_WAIT) ? ERROR : LOG,
1001  "could not signal for checkpoint: %m");
1002  break;
1003  }
1004  }
1005  else
1006  break; /* signal sent successfully */
1007 
1009  pg_usleep(100000L); /* wait 0.1 sec, then retry */
1010  }
1011 
1012  /*
1013  * If requested, wait for completion. We detect completion according to
1014  * the algorithm given above.
1015  */
1016  if (flags & CHECKPOINT_WAIT)
1017  {
1018  int new_started,
1019  new_failed;
1020 
1021  /* Wait for a new checkpoint to start. */
1023  for (;;)
1024  {
1026  new_started = CheckpointerShmem->ckpt_started;
1028 
1029  if (new_started != old_started)
1030  break;
1031 
1034  }
1036 
1037  /*
1038  * We are waiting for ckpt_done >= new_started, in a modulo sense.
1039  */
1041  for (;;)
1042  {
1043  int new_done;
1044 
1046  new_done = CheckpointerShmem->ckpt_done;
1047  new_failed = CheckpointerShmem->ckpt_failed;
1049 
1050  if (new_done - new_started >= 0)
1051  break;
1052 
1055  }
1057 
1058  if (new_failed != old_failed)
1059  ereport(ERROR,
1060  (errmsg("checkpoint request failed"),
1061  errhint("Consult recent messages in the server log for details.")));
1062  }
1063 }
#define MAX_SIGNAL_TRIES
void ConditionVariablePrepareToSleep(ConditionVariable *cv)
void ConditionVariableSleep(ConditionVariable *cv, uint32 wait_event_info)
int errmsg(const char *fmt,...)
Definition: elog.c:946
bool IsPostmasterEnvironment
Definition: globals.c:112
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:121
@ WAIT_EVENT_CHECKPOINT_START
Definition: wait_event.h:91
@ WAIT_EVENT_CHECKPOINT_DONE
Definition: wait_event.h:90
#define kill(pid, sig)
Definition: win32_port.h:482
#define CHECKPOINT_REQUESTED
Definition: xlog.h:141
#define CHECKPOINT_WAIT
Definition: xlog.h:140

References CHECK_FOR_INTERRUPTS, CHECKPOINT_IMMEDIATE, CHECKPOINT_REQUESTED, CHECKPOINT_WAIT, CheckpointerShmemStruct::checkpointer_pid, CheckpointerShmem, CheckpointerShmemStruct::ckpt_done, CheckpointerShmemStruct::ckpt_failed, CheckpointerShmemStruct::ckpt_flags, CheckpointerShmemStruct::ckpt_lck, CheckpointerShmemStruct::ckpt_started, ConditionVariableCancelSleep(), ConditionVariablePrepareToSleep(), ConditionVariableSleep(), CreateCheckPoint(), CheckpointerShmemStruct::done_cv, elog(), ereport, errhint(), errmsg(), ERROR, IsPostmasterEnvironment, kill, LOG, MAX_SIGNAL_TRIES, pg_usleep(), smgrcloseall(), SpinLockAcquire, SpinLockRelease, CheckpointerShmemStruct::start_cv, WAIT_EVENT_CHECKPOINT_DONE, and WAIT_EVENT_CHECKPOINT_START.

Referenced by CreateDatabaseUsingFileCopy(), do_pg_backup_start(), dropdb(), DropTableSpace(), movedb(), PerformRecoveryXLogAction(), standard_ProcessUtility(), StartupXLOG(), XLogPageRead(), and XLogWrite().

Variable Documentation

◆ BgWriterDelay

PGDLLIMPORT int BgWriterDelay
extern

Definition at line 61 of file bgwriter.c.

Referenced by BackgroundWriterMain(), and BgBufferSync().

◆ CheckPointCompletionTarget

PGDLLIMPORT double CheckPointCompletionTarget
extern

◆ CheckPointTimeout

PGDLLIMPORT int CheckPointTimeout
extern

Definition at line 144 of file checkpointer.c.

Referenced by CheckpointerMain(), and IsCheckpointOnSchedule().

◆ CheckPointWarning

PGDLLIMPORT int CheckPointWarning
extern

Definition at line 145 of file checkpointer.c.

Referenced by CheckpointerMain().