SQLite

Check-in [8f4cb9dd33]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Experiment with using an atomic CPU primitive instead of a mutex for intra-process locking with the unix-excl VFS.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | mutexfree-shmlock
Files: files | file ages | folders
SHA3-256: 8f4cb9dd3396bcaaf85dcdb4e3ae3c96f28a4d71d72665c4abf7c221370be626
User & Date: dan 2018-12-06 18:58:58.578
Context
2018-12-10
09:45
Avoid a mutex in-and-out in unixShmBarrier() on this branch. Use __sync_synchronize() instead. (check-in: a8c5fd86ce user: dan tags: mutexfree-shmlock)
2018-12-06
20:26
Add the mutexfree-shmlock experiment to the begin-concurrent-pnu branch. (check-in: 3aead209b4 user: dan tags: begin-concurrent-pnu-mutexfree-shmlock)
18:58
Experiment with using an atomic CPU primitive instead of a mutex for intra-process locking with the unix-excl VFS. (check-in: 8f4cb9dd33 user: dan tags: mutexfree-shmlock)
03:59
Invoking the sqlite3_trace() or sqlite3_trace_v2() interfaces cancels any sqlite3_profile() that is running. (check-in: ec63d3506b user: drh tags: trunk)
Changes
Unified Diff Show Whitespace Changes Patch
Changes to src/os_unix.c.
42
43
44
45
46
47
48



49
50
51
52
53
54
55
**   *  Locking primitives for the proxy uber-locking-method. (MacOSX only)
**   *  Definitions of sqlite3_vfs objects for all locking methods
**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */




/*
** There are various methods for file locking used for concurrency
** control:
**
**   1. POSIX locking (the default),
**   2. No locking,
**   3. Dot-file locking,







>
>
>







42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
**   *  Locking primitives for the proxy uber-locking-method. (MacOSX only)
**   *  Definitions of sqlite3_vfs objects for all locking methods
**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
*/
#include "sqliteInt.h"
#if SQLITE_OS_UNIX              /* This file is used on unix only */

/* Turn this feature on in all builds for now */
#define SQLITE_MUTEXFREE_SHMLOCK 1

/*
** There are various methods for file locking used for concurrency
** control:
**
**   1. POSIX locking (the default),
**   2. No locking,
**   3. Dot-file locking,
4235
4236
4237
4238
4239
4240
4241















4242















4243
4244
4245
4246
4247
4248
4249
  int nRef;                  /* Number of unixShm objects pointing to this */
  unixShm *pFirst;           /* All unixShm objects pointing to this */
#ifdef SQLITE_DEBUG
  u8 exclMask;               /* Mask of exclusive locks held */
  u8 sharedMask;             /* Mask of shared locks held */
  u8 nextShmId;              /* Next available unixShm.id value */
#endif















};
















/*
** Structure used internally by this VFS to record the state of an
** open shared memory connection.
**
** The following fields are initialized when this object is created and
** are read-only thereafter:







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>

>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
  int nRef;                  /* Number of unixShm objects pointing to this */
  unixShm *pFirst;           /* All unixShm objects pointing to this */
#ifdef SQLITE_DEBUG
  u8 exclMask;               /* Mask of exclusive locks held */
  u8 sharedMask;             /* Mask of shared locks held */
  u8 nextShmId;              /* Next available unixShm.id value */
#endif

#ifdef SQLITE_MUTEXFREE_SHMLOCK
  /* In unix-excl mode, if SQLITE_MUTEXFREE_SHMLOCK is defined, all locks
  ** are stored in the following 64-bit value. There are in total 8 
  ** shm-locking slots, each of which are assigned 8-bits from the 64-bit
  ** value. The least-significant 8 bits correspond to shm-locking slot
  ** 0, and so on.
  **
  ** If the 8-bits corresponding to a shm-locking locking slot are set to
  ** 0xFF, then a write-lock is held on the slot. Or, if they are set to
  ** a non-zero value smaller than 0xFF, then they represent the total 
  ** number of read-locks held on the slot. There is no way to distinguish
  ** between a write-lock and 255 read-locks.  */
  u64 lockmask;
#endif
};

/*
** Atomic CAS primitive used in multi-process mode. Equivalent to:
** 
**   int unixCompareAndSwap(u32 *ptr, u32 oldval, u32 newval){
**     if( *ptr==oldval ){
**       *ptr = newval;
**       return 1;
**     }
**     return 0;
**   }
*/
#define unixCompareAndSwap(ptr,oldval,newval) \
    __sync_bool_compare_and_swap(ptr,oldval,newval)


/*
** Structure used internally by this VFS to record the state of an
** open shared memory connection.
**
** The following fields are initialized when this object is created and
** are read-only thereafter:
4796
4797
4798
4799
4800
4801
4802




















































4803
4804
4805
4806
4807
4808
4809
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
  assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 );

  mask = (1<<(ofst+n)) - (1<<ofst);
  assert( n>1 || mask==(1<<ofst) );




















































  sqlite3_mutex_enter(pShmNode->pShmMutex);
  if( flags & SQLITE_SHM_UNLOCK ){
    u16 allMask = 0; /* Mask of locks held by siblings */

    /* See if any siblings hold this same lock */
    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
      if( pX==p ) continue;







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
  assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 );

  mask = (1<<(ofst+n)) - (1<<ofst);
  assert( n>1 || mask==(1<<ofst) );

#ifdef SQLITE_MUTEXFREE_SHMLOCK
  if( pDbFd->pInode->bProcessLock ){

    while( 1 ){
      u64 lockmask = pShmNode->lockmask;
      u64 newmask = lockmask;
      int i;
      for(i=ofst; i<n+ofst; i++){
        int ix8 = i*8;
        u8 v = (lockmask >> (ix8)) & 0xFF;
        if( flags & SQLITE_SHM_UNLOCK ){
          if( flags & SQLITE_SHM_EXCLUSIVE ){
            if( p->exclMask & (1 << i) ){
              newmask = newmask & ~((u64)0xFF<<ix8);
            }
          }else{
            if( p->sharedMask & (1 << i) ){
              newmask = newmask & ~((u64)0xFF<<ix8) | ((u64)(v-1)<<ix8);
            }
          }
        }else{
          if( flags & SQLITE_SHM_EXCLUSIVE ){
            if( v ) return SQLITE_BUSY;
            if( (p->exclMask & (1 << i))==0 ){
              newmask = newmask | ((u64)0xFF<<ix8);
            }
          }else{
            if( v==0xFF ) return SQLITE_BUSY;
            if( (p->sharedMask & (1 << i))==0 ){
              newmask = newmask & ~((u64)0xFF<<ix8) | ((u64)(v+1)<<ix8);
            }
          }
        }
      }

      if( unixCompareAndSwap(&pShmNode->lockmask, lockmask, newmask) ) break;
    }

    if( flags & SQLITE_SHM_UNLOCK ){
      p->sharedMask &= ~mask;
      p->exclMask &= ~mask;
    }else if( flags & SQLITE_SHM_EXCLUSIVE ){
      p->exclMask |= mask;
    }else{
      p->sharedMask |= mask;
    }

    return SQLITE_OK;
  }
#endif

  sqlite3_mutex_enter(pShmNode->pShmMutex);
  if( flags & SQLITE_SHM_UNLOCK ){
    u16 allMask = 0; /* Mask of locks held by siblings */

    /* See if any siblings hold this same lock */
    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
      if( pX==p ) continue;
Changes to src/test_vfs.c.
1558
1559
1560
1561
1562
1563
1564
1565





















































1566
1567

1568
1569
1570
1571

  return TCL_OK;

 bad_args:
  Tcl_WrongNumArgs(interp, 1, objv, "VFSNAME ?-noshm BOOL? ?-fullshm BOOL? ?-default BOOL? ?-mxpathname INT? ?-szosfile INT? ?-iversion INT?");
  return TCL_ERROR;
}






















































int Sqlitetestvfs_Init(Tcl_Interp *interp){
  Tcl_CreateObjCommand(interp, "testvfs", testvfs_cmd, 0, 0);

  return TCL_OK;
}

#endif








>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>


>




1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625

  return TCL_OK;

 bad_args:
  Tcl_WrongNumArgs(interp, 1, objv, "VFSNAME ?-noshm BOOL? ?-fullshm BOOL? ?-default BOOL? ?-mxpathname INT? ?-szosfile INT? ?-iversion INT?");
  return TCL_ERROR;
}

extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);
extern const char *sqlite3ErrName(int);

/*
** tclcmd: vfs_shmlock DB DBNAME (shared|exclusive) (lock|unlock) OFFSET N
*/
static int SQLITE_TCLAPI test_vfs_shmlock(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  const char *azArg1[] = {"shared", "exclusive", 0};
  const char *azArg2[] = {"lock", "unlock", 0};
  sqlite3 *db = 0;
  int rc = SQLITE_OK;
  const char *zDbname = 0;
  int iArg1 = 0;
  int iArg2 = 0;
  int iOffset = 0;
  int n = 0;
  sqlite3_file *pFd;

  if( objc!=7 ){
    Tcl_WrongNumArgs(interp, 1, objv, 
        "DB DBNAME (shared|exclusive) (lock|unlock) OFFSET N"
    );
    return TCL_ERROR;
  }

  zDbname = Tcl_GetString(objv[2]);
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) 
   || Tcl_GetIndexFromObj(interp, objv[3], azArg1, "ARG", 0, &iArg1) 
   || Tcl_GetIndexFromObj(interp, objv[4], azArg2, "ARG", 0, &iArg2) 
   || Tcl_GetIntFromObj(interp, objv[5], &iOffset)
   || Tcl_GetIntFromObj(interp, objv[6], &n)
  ){
    return TCL_ERROR;
  }

  sqlite3_file_control(db, zDbname, SQLITE_FCNTL_FILE_POINTER, (void*)&pFd);
  if( pFd==0 ){
    return TCL_ERROR;
  }
  rc = pFd->pMethods->xShmLock(pFd, iOffset, n, 
      (iArg1==0 ? SQLITE_SHM_SHARED : SQLITE_SHM_EXCLUSIVE)
    | (iArg2==0 ? SQLITE_SHM_LOCK : SQLITE_SHM_UNLOCK)
  );
  Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
  return TCL_OK;
}


int Sqlitetestvfs_Init(Tcl_Interp *interp){
  Tcl_CreateObjCommand(interp, "testvfs", testvfs_cmd, 0, 0);
  Tcl_CreateObjCommand(interp, "vfs_shmlock", test_vfs_shmlock, 0, 0);
  return TCL_OK;
}

#endif
Changes to test/lock_common.tcl.
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29




30
31
32
33
34
35
36
# This file contains code used by several different test scripts. The
# code in this file allows testfixture to control another process (or
# processes) to test locking.
#

proc do_multiclient_test {varname script} {

  foreach code [list {
    if {[info exists ::G(valgrind)]} { db close ; continue }
    set ::code2_chan [launch_testfixture]
    set ::code3_chan [launch_testfixture]
    proc code2 {tcl} { testfixture $::code2_chan $tcl }
    proc code3 {tcl} { testfixture $::code3_chan $tcl }
    set tn 1
  } {
    proc code2 {tcl} { uplevel #0 $tcl }
    proc code3 {tcl} { uplevel #0 $tcl }
    set tn 2
  }] {




    faultsim_delete_and_reopen

    proc code1 {tcl} { uplevel #0 $tcl }
  
    # Open connections [db2] and [db3]. Depending on which iteration this
    # is, the connections may be created in this interpreter, or in 
    # interpreters running in other OS processes. As such, the [db2] and [db3]







|





<
|


<

>
>
>
>







11
12
13
14
15
16
17
18
19
20
21
22
23

24
25
26

27
28
29
30
31
32
33
34
35
36
37
38
# This file contains code used by several different test scripts. The
# code in this file allows testfixture to control another process (or
# processes) to test locking.
#

proc do_multiclient_test {varname script} {

  foreach {tn code} [list 1 {
    if {[info exists ::G(valgrind)]} { db close ; continue }
    set ::code2_chan [launch_testfixture]
    set ::code3_chan [launch_testfixture]
    proc code2 {tcl} { testfixture $::code2_chan $tcl }
    proc code3 {tcl} { testfixture $::code3_chan $tcl }

  } 2 {
    proc code2 {tcl} { uplevel #0 $tcl }
    proc code3 {tcl} { uplevel #0 $tcl }

  }] {
    # Do not run multi-process tests with the unix-excl VFS.
    #
    if {$tn==1 && [permutation]=="unix-excl"} continue

    faultsim_delete_and_reopen

    proc code1 {tcl} { uplevel #0 $tcl }
  
    # Open connections [db2] and [db3]. Depending on which iteration this
    # is, the connections may be created in this interpreter, or in 
    # interpreters running in other OS processes. As such, the [db2] and [db3]
Changes to test/permutations.test.
602
603
604
605
606
607
608










609
610
611
612
613
614
615
  Run some tests using the "test_onefile.c" demo
} -initialize {
  set ::G(perm:sqlite3_args) [list -vfs fs]
} -files {
  conflict.test  insert.test   insert2.test  insert3.test
  rollback.test  select1.test  select2.test  select3.test
}











# Run some tests using UTF-16 databases.
#
test_suite "utf16" -description {
  Run tests using UTF-16 databases
} -presql {
  pragma encoding = 'UTF-16'







>
>
>
>
>
>
>
>
>
>







602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
  Run some tests using the "test_onefile.c" demo
} -initialize {
  set ::G(perm:sqlite3_args) [list -vfs fs]
} -files {
  conflict.test  insert.test   insert2.test  insert3.test
  rollback.test  select1.test  select2.test  select3.test
}

# Run some tests using the "unix-excl" VFS.
#
test_suite "unix-excl" -description {
  Run some tests using the "unix-excl" VFS
} -initialize {
  set ::G(perm:sqlite3_args) [list -vfs unix-excl]
} -files {
  shmlock.test
}

# Run some tests using UTF-16 databases.
#
test_suite "utf16" -description {
  Run tests using UTF-16 databases
} -presql {
  pragma encoding = 'UTF-16'
Added test/shmlock.test.






























































































































































































































>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
# 2018 December 6
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

set testprefix shmlock

ifcapable !wal {finish_test ; return }

sqlite3 db2 test.db
sqlite3 db3 test.db

do_execsql_test 1.0 {
  PRAGMA journal_mode = wal;
  CREATE TABLE t1(a, b);
  INSERT INTO t1 VALUES(1, 2);
} {wal}
do_test 1.1 { execsql { SELECT * FROM t1 } db2 } {1 2}
do_test 1.2 { execsql { SELECT * FROM t1 } db3 } {1 2}

foreach {tn dbhandle cmd res} {
  1    db  {shared    lock   7 1}    OK
  2    db2 {exclusive lock   7 1}    BUSY
  3    db  {shared    unlock 7 1}    OK
  4    db2 {exclusive lock   7 1}    OK
  5    db  {shared    lock   7 1}    BUSY
  6    db  {exclusive lock   7 1}    BUSY
  7    db2 {exclusive unlock 7 1}    OK

  8    db  {exclusive lock   0 8}    OK
  9    db  {exclusive unlock 0 8}    OK
  10   db2 {exclusive lock   0 8}    OK
  11   db2 {exclusive unlock 0 8}    OK

  12   db  {shared    lock   0 1}    OK
  13   db2 {shared    lock   0 1}    OK
  14   db3 {shared    lock   0 1}    OK
  15   db3 {shared    unlock 0 1}    OK
  16   db3 {exclusive lock   0 1}    BUSY
  17   db2 {shared    unlock 0 1}    OK
  18   db3 {exclusive lock   0 1}    BUSY
  19   db  {shared    unlock 0 1}    OK
  20   db3 {exclusive lock   0 1}    OK
  21   db3 {exclusive unlock 0 1}    OK

  22   db  {shared    lock   3 1}    OK
  23   db2 {exclusive lock   2 2}    BUSY
  24   db  {shared    lock   2 1}    OK
  25   db2 {exclusive lock   0 5}    BUSY
  26   db2 {exclusive lock   0 4}    BUSY
  27   db2 {exclusive lock   0 3}    BUSY
  28   db  {shared    unlock 3 1}    OK
  29   db2 {exclusive lock   2 2}    BUSY
  28   db  {shared    unlock 2 1}    OK
  29   db2 {exclusive lock   2 2}    OK
  29   db2 {exclusive unlock 2 2}    OK
} {
  do_test 1.3.$tn [list vfs_shmlock $dbhandle main {*}$cmd] "SQLITE_$res"
}

db  close
db2 close
db3 close

if {[permutation]=="unix-excl"} {
  do_test 2.0 {
    for {set i 0} {$i < 256} {incr i} { 
      sqlite3 db$i test.db 
      execsql { SELECT * FROM t1 } db$i
    }
    for {set i 0} {$i < 255} {incr i} { 
      set rc [vfs_shmlock db$i main shared lock 4 1]
      if {$rc != "SQLITE_OK"} { error $rc }
    }

    vfs_shmlock db255 main shared lock 4 1
  } {SQLITE_BUSY}

  do_test 2.1 { vfs_shmlock db255 main exclusive lock   4 1 } SQLITE_BUSY
  do_test 2.2 { vfs_shmlock db0   main shared    unlock 4 1 } SQLITE_OK
  do_test 2.3 { vfs_shmlock db255 main shared    lock   4 1 } SQLITE_OK
  do_test 2.4 { vfs_shmlock db255 main shared    unlock 4 1 } SQLITE_OK
  do_test 2.5 { vfs_shmlock db255 main exclusive lock   4 1 } SQLITE_BUSY

  do_test 2.6 {
    for {set i 1} {$i < 255} {incr i} { 
      set rc [vfs_shmlock db255 main exclusive lock 4 1]
      if {$rc != "SQLITE_BUSY"} { error $rc }
      set rc [vfs_shmlock db$i main shared unlock 4 1]
      if {$rc != "SQLITE_OK"} { error $rc }
    }

    vfs_shmlock db255 main exclusive lock 4 1
  } {SQLITE_OK}

  vfs_shmlock db255 main exclusive unlock 4 1
}

finish_test


Changes to test/wal.test.
1293
1294
1295
1296
1297
1298
1299

1300
1301
1302
1303
1304
1305
1306
#
#   3. Using connection 1, checkpoint the database. Make sure all
#      the data is present and the database is not corrupt.
#
# At one point, SQLite was failing to grow the mapping of the wal-index
# file in step 3 and the checkpoint was corrupting the database file.
#

do_test wal-20.1 {
  catch {db close}
  forcedelete test.db test.db-wal test.db-journal
  sqlite3 db test.db
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(x);







>







1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
#
#   3. Using connection 1, checkpoint the database. Make sure all
#      the data is present and the database is not corrupt.
#
# At one point, SQLite was failing to grow the mapping of the wal-index
# file in step 3 and the checkpoint was corrupting the database file.
#
if {[permutation]!="unix-excl"} {
do_test wal-20.1 {
  catch {db close}
  forcedelete test.db test.db-wal test.db-journal
  sqlite3 db test.db
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(x);
1338
1339
1340
1341
1342
1343
1344

1345
1346
1347
1348
1349
1350
1351
} {16384}
do_test wal-20.4 {
  db close
  sqlite3 db test.db
  execsql { SELECT count(*) FROM t1 }
} {16384}
integrity_check wal-20.5


catch { db2 close }
catch { db close }

do_test wal-21.1 {
  faultsim_delete_and_reopen
  execsql { 







>







1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
} {16384}
do_test wal-20.4 {
  db close
  sqlite3 db test.db
  execsql { SELECT count(*) FROM t1 }
} {16384}
integrity_check wal-20.5
}

catch { db2 close }
catch { db close }

do_test wal-21.1 {
  faultsim_delete_and_reopen
  execsql {