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I don't like last minute patches before the final freeze, but I believe that 

this one could be useful for people experiencing out-of-memory crashes while
executing queries which retrieve or use a very large number of tuples.

The problem happens when storage is allocated for functions results used in
a large query, for example:

  select upper(name) from big_table;
  select big_table.array[1] from big_table;
  select count(upper(name)) from big_table;

This patch is a dirty hack that fixes the out-of-memory problem for the most
common cases, like the above ones. It is not the final solution for the
problem but it can work for some people, so I'm posting it.

The patch should be safe because all changes are under #ifdef. Furthermore
the feature can be enabled or disabled at runtime by the `free_tuple_memory'
options in the pg_options file. The option is disabled by default and must
be explicitly enabled at runtime to have any effect.

To enable the patch add the follwing line to Makefile.custom:

CUSTOM_COPT += -DFREE_TUPLE_MEMORY

To enable the option at runtime add the following line to pg_option:

free_tuple_memory=1

Massimo
This commit is contained in:
Bruce Momjian 1999-06-12 14:05:41 +00:00
parent bd470ba47e
commit 603e153bb8
6 changed files with 111 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
src/backend/access/common/heaptuple.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.51 1999/05/25 16:06:35 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.52 1999/06/12 14:05:36 momjian Exp $
*
* NOTES
* The old interface functions have been converted to macros
@ -27,6 +27,11 @@
#include <storage/bufpage.h>
#include <utils/memutils.h>
#ifdef FREE_TUPLE_MEMORY
#include <utils/portal.h>
#include <utils/trace.h>
#endif
#ifndef HAVE_MEMMOVE
#include <regex/utils.h>
#else
@ -93,6 +98,9 @@ DataFill(char *data,
int i;
int numberOfAttributes = tupleDesc->natts;
Form_pg_attribute *att = tupleDesc->attrs;
#ifdef FREE_TUPLE_MEMORY
bool free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
#endif
if (bit != NULL)
{
@ -131,6 +139,14 @@ DataFill(char *data,
*infomask |= HEAP_HASVARLENA;
data_length = VARSIZE(DatumGetPointer(value[i]));
memmove(data, DatumGetPointer(value[i]), data_length);
#ifdef FREE_TUPLE_MEMORY
/* try to pfree value[i] - dz */
if (free_tuple_memory &&
PortalHeapMemoryIsValid(CurrentMemoryContext,
(Pointer) value[i])) {
pfree(value[i]);
}
#endif
break;
case sizeof(char):
*data = att[i]->attbyval ?
@ -147,8 +163,15 @@ DataFill(char *data,
*((int32 *) value[i]));
break;
default:
memmove(data, DatumGetPointer(value[i]),
att[i]->attlen);
memmove(data, DatumGetPointer(value[i]), att[i]->attlen);
#ifdef FREE_TUPLE_MEMORY
/* try to pfree value[i] - dz */
if (free_tuple_memory &&
PortalHeapMemoryIsValid(CurrentMemoryContext,
(Pointer) value[i])) {
pfree(value[i]);
}
#endif
break;
}
data = (char *) att_addlength((long) data, att[i]->attlen, value[i]);

48
src/backend/executor/nodeAgg.c
View File

@ -31,6 +31,11 @@
#include "utils/syscache.h"
#include "optimizer/clauses.h"
#ifdef FREE_TUPLE_MEMORY
#include <utils/portal.h>
#include <utils/trace.h>
#endif
/*
* AggFuncInfo -
* keeps the transition functions information around
@ -113,7 +118,9 @@ ExecAgg(Agg *node)
isNull1 = FALSE,
isNull2 = FALSE;
bool qual_result;
#ifdef FREE_TUPLE_MEMORY
bool free_tuple_memory = pg_options[OPT_FREE_TUPLE_MEMORY];
#endif
/* ---------------------
* get state info from node
@ -241,6 +248,10 @@ ExecAgg(Agg *node)
for (;;)
{
TupleTableSlot *outerslot;
#ifdef FREE_TUPLE_MEMORY
Oid valueType;
bool isByValue = 0;
#endif
isNull = isNull1 = isNull2 = 0;
outerslot = ExecProcNode(outerPlan, (Plan *) node);
@ -293,6 +304,31 @@ ExecAgg(Agg *node)
newVal = ExecEvalExpr(aggref->target, econtext,
&isNull, &isDone);
}
#ifdef FREE_TUPLE_MEMORY
if (free_tuple_memory) {
switch (nodeTag(aggref->target)) {
case T_Const:
isByValue = ((Const*) (aggref->target))->constbyval;
break;
case T_Var:
valueType = ((Var*) (aggref->target))->vartype;
isByValue = typeByVal(typeidType(valueType));
break;
case T_Array:
isByValue = ((Array*)(aggref->target))->arrayelembyval;
break;
case T_ArrayRef:
isByValue =((ArrayRef*)(aggref->target))->refelembyval;
break;
case T_Expr:
valueType = ((Expr*) (aggref->target))->typeOid;
isByValue = typeByVal(typeidType(valueType));
break;
default:
break;
}
}
#endif
if (isNull && !aggref->usenulls)
continue; /* ignore this tuple for this agg */
@ -353,6 +389,16 @@ ExecAgg(Agg *node)
(FmgrValues *) args, &isNull2);
Assert(!isNull2);
}
#ifdef FREE_TUPLE_MEMORY
/* try to pfree newVal if not isByValue - dz */
if (free_tuple_memory && !isByValue &&
PortalHeapMemoryIsValid(CurrentMemoryContext,
(Pointer) newVal))
{
pfree(newVal);
}
#endif
}
/*

11
src/backend/utils/misc/trace.c
View File

@ -73,6 +73,9 @@ static char *opt_names[] = {
"syslog", /* use syslog for error messages */
"hostlookup", /* enable hostname lookup in ps_status */
"showportnumber", /* show port number in ps_status */
#ifdef FREE_TUPLE_MEMORY
"free_tuple_memory", /* try to pfree memory for each tuple */
#endif
/* NUM_PG_OPTIONS */ /* must be the last item of enum */
};
@ -404,9 +407,9 @@ read_pg_options(SIGNAL_ARGS)
}
/*
* Local variables:
* tab-width: 4
* c-indent-level: 4
* c-basic-offset: 4
* Local Variables:
* tab-width: 4
* c-indent-level: 4
* c-basic-offset: 4
* End:
*/

20
src/backend/utils/mmgr/portalmem.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.19 1999/05/25 16:12:55 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.20 1999/06/12 14:05:39 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -289,6 +289,24 @@ PortalHeapMemoryFree(PortalHeapMemory this,
}
}
#ifdef FREE_TUPLE_MEMORY
/*
* PortalHeapMemoryIsValid --
*
* Check if a pointer is allocated in a memory context.
*
*/
bool
PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer)
{
HeapMemoryBlock block = HEAPMEMBLOCK((PortalHeapMemory) context);
AssertState(PointerIsValid(block));
return (AllocSetContains(&block->setData, pointer));
}
#endif
/* ----------------
* PortalHeapMemoryRealloc
* ----------------

6
src/include/utils/portal.h
View File

@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: portal.h,v 1.13 1999/05/25 16:14:57 momjian Exp $
* $Id: portal.h,v 1.14 1999/06/12 14:05:40 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -80,6 +80,10 @@ extern void EndPortalAllocMode(void);
extern PortalVariableMemory PortalGetVariableMemory(Portal portal);
extern PortalHeapMemory PortalGetHeapMemory(Portal portal);
#ifdef FREE_TUPLE_MEMORY
bool PortalHeapMemoryIsValid(MemoryContext context, Pointer pointer);
#endif
/* estimate of the maximum number of open portals a user would have,
* used in initially sizing the PortalHashTable in EnablePortalManager()
*/

11
src/include/utils/trace.h
View File

@ -64,6 +64,9 @@ enum pg_option_enum {
OPT_SYSLOG, /* use syslog for error messages */
OPT_HOSTLOOKUP, /* enable hostname lookup in ps_status */
OPT_SHOWPORTNUMBER, /* show port number in ps_status */
#ifdef FREE_TUPLE_MEMORY
OPT_FREE_TUPLE_MEMORY, /* try to pfree memory for each tuple */
#endif
NUM_PG_OPTIONS /* must be the last item of enum */
};
@ -83,9 +86,9 @@ extern int pg_options[NUM_PG_OPTIONS];
#endif /* TRACE_H */
/*
* Local variables:
* tab-width: 4
* c-indent-level: 4
* c-basic-offset: 4
* Local Variables:
* tab-width: 4
* c-indent-level: 4
* c-basic-offset: 4
* End:
*/