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Commite0058b6

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committed
Theses buffer leaks are caused by indexes that are kept open between
calls. Outside a transaction, the backend detects them as bufferleaks; it sends a NOTICE, and frees them. This sometimes cause asegmentation fault (at least on Linux). These indexes are initializedon the first lo_read/lo_write/lo_tell call, and (normally) closedon a lo_close call. Thus the buffer leaks appear when lo directaccess functions are used, and not with lo_import/lo_export functions(libpq version calls lo_close before ending the command, and thebackend version uses another path).The included patches (against recent snapshot, and against 6.3.2)cause indexes to be closed on transaction end (that is on explicit'END' statment, or on command termination outside trasaction blocks),thus preventing the buffer leaks while increasing performance insidetransactions. Some (all?) 'classic' memory leaks are also removed.I hope it will be ok.--- Pascal ANDRE, graduated from Ecole Centrale Paris andre@via.ecp.fr
1 parent7702d7a commite0058b6

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5 files changed

+96
-9
lines changed

5 files changed

+96
-9
lines changed

‎src/backend/access/transam/xact.c

Lines changed: 13 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.20 1998/06/15 19:28:02 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.21 1998/07/21 04:17:21 momjian Exp $
1111
*
1212
* NOTES
1313
*Transaction aborts can now occur two ways:
@@ -137,6 +137,11 @@
137137
*-------------------------------------------------------------------------
138138
*/
139139

140+
/*
141+
* Large object clean up added in CommitTransaction() to prevent buffer leaks.
142+
* [PA, 7/17/98]
143+
* [PA] is Pascal André <andre@via.ecp.fr>
144+
*/
140145
#include<postgres.h>
141146

142147
#include<access/xact.h>
@@ -151,6 +156,9 @@
151156
#include<commands/async.h>
152157
#include<commands/sequence.h>
153158

159+
/* included for _lo_commit [PA, 7/17/98] */
160+
#include<libpq/be-fsstubs.h>
161+
154162
staticvoidAbortTransaction(void);
155163
staticvoidAtAbort_Cache(void);
156164
staticvoidAtAbort_Locks(void);
@@ -889,6 +897,10 @@ CommitTransaction()
889897
*do commit processing
890898
* ----------------
891899
*/
900+
901+
/* handle commit for large objects [ PA, 7/17/98 ] */
902+
_lo_commit();
903+
892904
CloseSequences();
893905
DestroyTempRels();
894906
AtEOXact_portals();

‎src/backend/libpq/be-fsstubs.c

Lines changed: 23 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.21 1998/06/15 19:28:25 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/libpq/be-fsstubs.c,v 1.22 1998/07/21 04:17:23 momjian Exp $
1111
*
1212
* NOTES
1313
* This should be moved to a more appropriate place. It is here
@@ -41,6 +41,8 @@
4141
#include<storage/large_object.h>
4242
#include<libpq/be-fsstubs.h>
4343

44+
/* [PA] is Pascal André <andre@via.ecp.fr> */
45+
4446
/*#define FSDB 1*/
4547
#defineMAX_LOBJ_FDS 256
4648

@@ -52,7 +54,6 @@ static GlobalMemory fscxt = NULL;
5254
staticintnewLOfd(LargeObjectDesc*lobjCookie);
5355
staticvoiddeleteLOfd(intfd);
5456

55-
5657
/*****************************************************************************
5758
*File Interfaces for Large Objects
5859
*****************************************************************************/
@@ -367,6 +368,26 @@ lo_export(Oid lobjId, text *filename)
367368
return1;
368369
}
369370

371+
/*
372+
* lo_commit -
373+
* prepares large objects for transaction commit [PA, 7/17/98]
374+
*/
375+
void
376+
_lo_commit(void)
377+
{
378+
inti;
379+
MemoryContextcurrentContext;
380+
381+
currentContext=MemoryContextSwitchTo((MemoryContext)fscxt);
382+
383+
for (i=0;i<MAX_LOBJ_FDS;i++) {
384+
if (cookies[i]!=NULL)inv_cleanindex(cookies[i]);
385+
}
386+
387+
MemoryContextSwitchTo(currentContext);
388+
389+
}
390+
370391

371392
/*****************************************************************************
372393
*Support routines for this file

‎src/backend/storage/large_object/inv_api.c

Lines changed: 50 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.30 1998/06/15 19:29:16 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/storage/large_object/inv_api.c,v 1.31 1998/07/21 04:17:24 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -60,6 +60,19 @@
6060
*for data.
6161
*/
6262

63+
/*
64+
* In order to prevent buffer leak on transaction commit, large object
65+
* scan index handling has been modified. Indexes are persistant inside
66+
* a transaction but may be closed between two calls to this API (when
67+
* transaction is committed while object is opened, or when no
68+
* transaction is active). Scan indexes are thus now reinitialized using
69+
* the object current offset. [PA]
70+
*
71+
* Some cleanup has been also done for non freed memory.
72+
*
73+
* For subsequent notes, [PA] is Pascal André <andre@via.ecp.fr>
74+
*/
75+
6376
#defineIFREESPC(p)(PageGetFreeSpace(p) - sizeof(HeapTupleData) - sizeof(struct varlena) - sizeof(int32))
6477
#defineIMAXBLK8092
6578
#defineIMINBLK512
@@ -261,8 +274,11 @@ inv_close(LargeObjectDesc *obj_desc)
261274
{
262275
Assert(PointerIsValid(obj_desc));
263276

264-
if (obj_desc->iscan!= (IndexScanDesc)NULL)
277+
if (obj_desc->iscan!= (IndexScanDesc)NULL) {
265278
index_endscan(obj_desc->iscan);
279+
pfree(obj_desc->iscan);
280+
obj_desc->iscan=NULL;
281+
}
266282

267283
heap_close(obj_desc->heap_r);
268284
index_close(obj_desc->index_r);
@@ -546,6 +562,28 @@ inv_write(LargeObjectDesc *obj_desc, char *buf, int nbytes)
546562
return (nwritten);
547563
}
548564

565+
/*
566+
* inv_cleanindex --
567+
* Clean opened indexes for large objects, and clears current result.
568+
* This is necessary on transaction commit in order to prevent buffer
569+
* leak.
570+
* This function must be called for each opened large object.
571+
* [ PA, 7/17/98 ]
572+
*/
573+
void
574+
inv_cleanindex(LargeObjectDesc*obj_desc)
575+
{
576+
Assert(PointerIsValid(obj_desc));
577+
578+
if (obj_desc->iscan== (IndexScanDesc)NULL)return;
579+
580+
index_endscan(obj_desc->iscan);
581+
pfree(obj_desc->iscan);
582+
obj_desc->iscan= (IndexScanDesc)NULL;
583+
584+
ItemPointerSetInvalid(&(obj_desc->htid));
585+
}
586+
549587
/*
550588
*inv_fetchtup -- Fetch an inversion file system block.
551589
*
@@ -591,8 +629,13 @@ inv_fetchtup(LargeObjectDesc *obj_desc, Buffer *bufP)
591629
{
592630
ScanKeyDataskey;
593631

632+
/*
633+
* As scan index may be prematurely closed (on commit),
634+
* we must use object current offset (was 0) to
635+
* reinitialize the entry [ PA ].
636+
*/
594637
ScanKeyEntryInitialize(&skey,0x0,1,F_INT4GE,
595-
Int32GetDatum(0));
638+
Int32GetDatum(obj_desc->offset));
596639
obj_desc->iscan=
597640
index_beginscan(obj_desc->index_r,
598641
(bool)0, (uint16)1,
@@ -622,7 +665,7 @@ inv_fetchtup(LargeObjectDesc *obj_desc, Buffer *bufP)
622665

623666
/* remember this tid -- we may need it for later reads/writes */
624667
ItemPointerCopy(&(res->heap_iptr),&(obj_desc->htid));
625-
668+
pfree(res);
626669
}
627670
else
628671
{
@@ -1179,6 +1222,7 @@ _inv_getsize(Relation hreln, TupleDesc hdesc, Relation ireln)
11791222
if (res== (RetrieveIndexResult)NULL)
11801223
{
11811224
index_endscan(iscan);
1225+
pfree(iscan);
11821226
return (0);
11831227
}
11841228

@@ -1192,11 +1236,13 @@ _inv_getsize(Relation hreln, TupleDesc hdesc, Relation ireln)
11921236
ReleaseBuffer(buf);
11931237

11941238
htup=heap_fetch(hreln, false,&(res->heap_iptr),&buf);
1239+
pfree(res);
11951240

11961241
}while (!HeapTupleIsValid(htup));
11971242

11981243
/* don't need the index scan anymore */
11991244
index_endscan(iscan);
1245+
pfree(iscan);
12001246

12011247
/* get olastbyte attribute */
12021248
d=heap_getattr(htup,1,hdesc,&isNull);

‎src/include/libpq/be-fsstubs.h

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: be-fsstubs.h,v 1.5 1997/09/08 21:52:33 momjian Exp $
9+
* $Id: be-fsstubs.h,v 1.6 1998/07/21 04:17:26 momjian Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -37,4 +37,9 @@ extern intlo_unlink(Oid lobjId);
3737
externstructvarlena*loread(intfd,intlen);
3838
externintlowrite(intfd,structvarlena*wbuf);
3939

40+
/*
41+
* Added for buffer leak prevention [ Pascal André <andre@via.ecp.fr> ]
42+
*/
43+
externvoid_lo_commit(void);
44+
4045
#endif/* BE_FSSTUBS_H */

‎src/include/storage/large_object.h

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
* Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Id: large_object.h,v 1.7 1997/09/08 21:54:29 momjian Exp $
10+
* $Id: large_object.h,v 1.8 1998/07/21 04:17:30 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -54,4 +54,7 @@ extern intinv_tell(LargeObjectDesc *obj_desc);
5454
externintinv_read(LargeObjectDesc*obj_desc,char*buf,intnbytes);
5555
externintinv_write(LargeObjectDesc*obj_desc,char*buf,intnbytes);
5656

57+
/* added for buffer leak prevention [ PA ] */
58+
externvoidinv_cleanindex(LargeObjectDesc*obj_desc);
59+
5760
#endif/* LARGE_OBJECT_H */

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