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Commite77b630

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committed
Allow maximum number of backends to be set at configure time
(--with-maxbackends). Add a postmaster switch (-N backends) that allowsthe limit to be reduced at postmaster start time. (You can't increase it,sorry to say, because there are still some fixed-size arrays.)Grab the number of semaphores indicated by min(MAXBACKENDS, -N) atpostmaster startup, so that this particular form of bogus configurationis exposed immediately rather than under heavy load.
1 parent612b843 commite77b630

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14 files changed

+502
-392
lines changed

14 files changed

+502
-392
lines changed

‎src/backend/postmaster/postmaster.c

Lines changed: 34 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.101 1999/02/13 23:17:40 momjian Exp $
13+
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.102 1999/02/19 06:06:00 tgl Exp $
1414
*
1515
* NOTES
1616
*
@@ -162,8 +162,17 @@ static IpcMemoryKey ipc_key;
162162
* adding to this.
163163
*/
164164

165+
staticintMaxBackends=MAXBACKENDS;
165166

166-
staticintNextBackendId=MAXINT;/* XXX why? */
167+
/*
168+
* MaxBackends is the actual soft limit on the number of backends
169+
* we will start. It defaults to the hard limit established at compilation
170+
* time, but can be readjusted with postmaster's xxx switch.
171+
* One reason to reduce MaxBackends is to allow startup under a kernel
172+
* that won't let us get MAXBACKENDS semaphores!
173+
*/
174+
175+
staticintNextBackendTag=MAXINT;/* XXX why count down not up? */
167176
staticchar*progname= (char*)NULL;
168177
staticchar**real_argv;
169178
staticintreal_argc;
@@ -388,7 +397,7 @@ PostmasterMain(int argc, char *argv[])
388397
DataDir=getenv("PGDATA");/* default value */
389398

390399
opterr=0;
391-
while ((opt=getopt(nonblank_argc,argv,"A:a:B:b:D:dim:Mno:p:Ss"))!=EOF)
400+
while ((opt=getopt(nonblank_argc,argv,"A:a:B:b:D:dim:MN:no:p:Ss"))!=EOF)
392401
{
393402
switch (opt)
394403
{
@@ -463,6 +472,17 @@ PostmasterMain(int argc, char *argv[])
463472
* 'postmaster'
464473
*/
465474
break;
475+
case'N':
476+
/*
477+
* The max number of backends to start.
478+
* Can't set to less than 1 or more than compiled-in limit.
479+
*/
480+
MaxBackends=atoi(optarg);
481+
if (MaxBackends<1)
482+
MaxBackends=1;
483+
if (MaxBackends>MAXBACKENDS)
484+
MaxBackends=MAXBACKENDS;
485+
break;
466486
case'n':
467487
/* Don't reinit shared mem after abnormal exit */
468488
Reinit= false;
@@ -621,6 +641,8 @@ usage(const char *progname)
621641
fprintf(stderr,"\t-b backend\tuse a specific backend server executable\n");
622642
fprintf(stderr,"\t-d [1|2|3]\tset debugging level\n");
623643
fprintf(stderr,"\t-i \t\tlisten on TCP/IP sockets as well as Unix domain socket\n");
644+
fprintf(stderr,"\t-N nprocs\tset max number of backend servers (1..%d)\n",
645+
MAXBACKENDS);
624646
fprintf(stderr,"\t-n \t\tdon't reinitialize shared memory after abnormal exit\n");
625647
fprintf(stderr,"\t-o option\tpass 'option' to each backend servers\n");
626648
fprintf(stderr,"\t-p port\tspecify port for postmaster to listen on\n");
@@ -765,7 +787,7 @@ ServerLoop(void)
765787
if (status==STATUS_OK&&port->pktInfo.state==Idle)
766788
{
767789
/* Can't start backend if max backend count is exceeded. */
768-
if (CountChildren() >=MaxBackendId)
790+
if (CountChildren() >=MaxBackends)
769791
PacketSendError(&port->pktInfo,
770792
"Sorry, too many clients already");
771793
else
@@ -1009,7 +1031,7 @@ static void
10091031
reset_shared(shortport)
10101032
{
10111033
ipc_key=port*1000+shmem_seq*100;
1012-
CreateSharedMemoryAndSemaphores(ipc_key);
1034+
CreateSharedMemoryAndSemaphores(ipc_key,MaxBackends);
10131035
ActiveBackends= FALSE;
10141036
shmem_seq+=1;
10151037
if (shmem_seq >=10)
@@ -1272,7 +1294,7 @@ BackendStartup(Port *port)
12721294
*/
12731295
sprintf(envEntry[0],"POSTPORT=%d",PostPortName);
12741296
putenv(envEntry[0]);
1275-
sprintf(envEntry[1],"POSTID=%d",NextBackendId);
1297+
sprintf(envEntry[1],"POSTID=%d",NextBackendTag);
12761298
putenv(envEntry[1]);
12771299
sprintf(envEntry[2],"PG_USER=%s",port->user);
12781300
putenv(envEntry[2]);
@@ -1348,9 +1370,11 @@ BackendStartup(Port *port)
13481370
progname,pid,port->user,port->database,
13491371
port->sock);
13501372

1351-
/* adjust backend counter */
1352-
/* XXX Don't know why this is done, but for now backend needs it */
1353-
NextBackendId-=1;
1373+
/* Generate a new backend tag for every backend we start */
1374+
/* XXX theoretically this could wrap around, if you have the patience
1375+
* to start 2^31 backends ...
1376+
*/
1377+
NextBackendTag-=1;
13541378

13551379
/*
13561380
* Everything's been successful, it's safe to add this backend to our
@@ -1459,7 +1483,7 @@ DoBackend(Port *port)
14591483
/* OK, let's unblock our signals, all together now... */
14601484
sigprocmask(SIG_SETMASK,&oldsigmask,0);
14611485

1462-
/* Close thepostmater sockets */
1486+
/* Close thepostmaster sockets */
14631487
if (NetServer)
14641488
StreamClose(ServerSock_INET);
14651489
#ifndef__CYGWIN32__

‎src/backend/storage/ipc/ipci.c

Lines changed: 7 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.18 1999/02/13 23:18:11 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.19 1999/02/19 06:06:04 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -44,17 +44,19 @@ SystemPortAddressCreateIPCKey(SystemPortAddress address)
4444
4545
CreateSharedMemoryAndSemaphores
4646
is called exactly *ONCE* by the postmaster.
47-
It is *NEVER* called by the postgres backend
47+
It is *NEVER* called by the postgres backend,
48+
except in the case of a standalone backend.
4849
4950
0) destroy any existing semaphores for both buffer
5051
and lock managers.
5152
1) create the appropriate *SHARED* memory segments
5253
for the two resource managers.
54+
2) create shared semaphores as needed.
5355
5456
**************************************************/
5557

5658
void
57-
CreateSharedMemoryAndSemaphores(IPCKeykey)
59+
CreateSharedMemoryAndSemaphores(IPCKeykey,intmaxBackends)
5860
{
5961
intsize;
6062

@@ -98,7 +100,7 @@ CreateSharedMemoryAndSemaphores(IPCKey key)
98100
*do process table stuff
99101
* ----------------
100102
*/
101-
InitProcGlobal(key);
103+
InitProcGlobal(key,maxBackends);
102104
on_shmem_exit(ProcFreeAllSemaphores,NULL);
103105

104106
CreateSharedInvalidationState(key);
@@ -120,7 +122,7 @@ AttachSharedMemoryAndSemaphores(IPCKey key)
120122
*/
121123
if (key==PrivateIPCKey)
122124
{
123-
CreateSharedMemoryAndSemaphores(key);
125+
CreateSharedMemoryAndSemaphores(key,1);
124126
return;
125127
}
126128

‎src/backend/storage/ipc/sinvaladt.c

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.16 1999/02/13 23:18:16 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.17 1999/02/19 06:06:03 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -119,7 +119,7 @@ SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag)
119119

120120
stateP=NULL;
121121

122-
for (index=0;index<MaxBackendId;index+=1)
122+
for (index=0;index<MAXBACKENDS;index++)
123123
{
124124
if (segInOutP->procState[index].tag==InvalidBackendTag||
125125
segInOutP->procState[index].tag==backendTag)
@@ -141,7 +141,7 @@ SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag)
141141

142142
/* verify that all "procState" entries checked for matching tags */
143143

144-
for (index+=1;index<MaxBackendId;index+=1)
144+
for (index++;index<MAXBACKENDS;index++)
145145
{
146146
if (segInOutP->procState[index].tag==backendTag)
147147
{
@@ -565,7 +565,7 @@ SIDecProcLimit(SISeg *segP, int num)
565565
{
566566
inti;
567567

568-
for (i=0;i<MaxBackendId;i++)
568+
for (i=0;i<MAXBACKENDS;i++)
569569
{
570570
/* decrement only, if there is a limit > 0*/
571571
if (segP->procState[i].limit>0)
@@ -622,7 +622,7 @@ SISetProcStateInvalid(SISeg *segP)
622622
{
623623
inti;
624624

625-
for (i=0;i<MaxBackendId;i++)
625+
for (i=0;i<MAXBACKENDS;i++)
626626
{
627627
if (segP->procState[i].limit==0)
628628
{
@@ -696,7 +696,7 @@ SIDelExpiredDataEntries(SISeg *segP)
696696
h;
697697

698698
min=9999999;
699-
for (i=0;i<MaxBackendId;i++)
699+
for (i=0;i<MAXBACKENDS;i++)
700700
{
701701
h=SIGetProcStateLimit(segP,i);
702702
if (h >=0)
@@ -740,7 +740,7 @@ SISegInit(SISeg *segP)
740740
SISetEndEntryChain(segP,InvalidOffset);
741741
SISetNumEntries(segP,0);
742742
SISetMaxNumEntries(segP,MAXNUMMESSAGES);
743-
for (i=0;i<MaxBackendId;i++)
743+
for (i=0;i<MAXBACKENDS;i++)
744744
{
745745
segP->procState[i].limit=-1;/* no backend active !! */
746746
segP->procState[i].resetState= false;

‎src/backend/storage/lmgr/lock.c

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.41 1999/02/13 23:18:25 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.42 1999/02/19 06:06:06 tgl Exp $
1111
*
1212
* NOTES
1313
* Outside modules can create a lock table and acquire/release
@@ -1492,8 +1492,8 @@ LockShmemSize()
14921492
nXidBuckets=1 << (int)my_log2((NLOCKS_PER_XACT-1) /DEF_FFACTOR+1);
14931493
nXidSegs=1 << (int)my_log2((nLockBuckets-1) /DEF_SEGSIZE+1);
14941494

1495-
size+=MAXALIGN(NBACKENDS*sizeof(PROC));/* each MyProc */
1496-
size+=MAXALIGN(NBACKENDS*sizeof(LOCKMETHODCTL));/* each
1495+
size+=MAXALIGN(MAXBACKENDS*sizeof(PROC));/* each MyProc */
1496+
size+=MAXALIGN(MAXBACKENDS*sizeof(LOCKMETHODCTL));/* each
14971497
* lockMethodTable->ctl */
14981498
size+=MAXALIGN(sizeof(PROC_HDR));/* ProcGlobal */
14991499

@@ -1504,10 +1504,10 @@ LockShmemSize()
15041504
(MAXALIGN(sizeof(BUCKET_INDEX))+
15051505
MAXALIGN(sizeof(LOCK)));/* contains hash key */
15061506

1507-
size+=MAXALIGN(my_log2(NBACKENDS)*sizeof(void*));
1507+
size+=MAXALIGN(my_log2(MAXBACKENDS)*sizeof(void*));
15081508
size+=MAXALIGN(sizeof(HHDR));
15091509
size+=nXidSegs*MAXALIGN(DEF_SEGSIZE*sizeof(SEGMENT));
1510-
size+=NBACKENDS*/* XXX not multiple of BUCKET_ALLOC_INCR? */
1510+
size+=MAXBACKENDS*/* XXX not multiple of BUCKET_ALLOC_INCR? */
15111511
(MAXALIGN(sizeof(BUCKET_INDEX))+
15121512
MAXALIGN(sizeof(XIDLookupEnt)));/* contains hash key */
15131513

@@ -1552,7 +1552,7 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
15521552
HTAB*xidTable;
15531553
boolfound;
15541554

1555-
staticPROC*checked_procs[MaxBackendId];
1555+
staticPROC*checked_procs[MAXBACKENDS];
15561556
staticintnprocs;
15571557
staticboolMyNHolding;
15581558

@@ -1674,7 +1674,7 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
16741674
if (j >=nprocs&&lock!=findlock)
16751675
{
16761676
checked_procs[nprocs++]=proc;
1677-
Assert(nprocs <=MaxBackendId);
1677+
Assert(nprocs <=MAXBACKENDS);
16781678

16791679
/*
16801680
* For non-MyProc entries, we are looking only

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