Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit07172d5

Browse files
committed
Avoid query-lifetime memory leaks in XMLTABLE (bug #15321)
Multiple calls to XMLTABLE in a query (e.g. laterally applying it to atable with an xml column, an important use-case) were leaking largeamounts of memory into the per-query context, blowing up memory usage.Repair by reorganizing memory context usage in nodeTableFuncscan; usethe usual per-tuple context for row-by-row evaluations instead ofperValueCxt, and use the explicitly created context -- renamed fromperValueCxt to perTableCxt -- for arguments and state for eachindividual table-generation operation.Backpatch to PG10 where this code was introduced.Original report by IRC user begriffs; analysis and patch by me.Reviewed by Tom Lane and Pavel Stehule.Discussion:https://postgr.es/m/153394403528.10284.7530399040974170549@wrigleys.postgresql.org
1 parent46b5e7c commit07172d5

File tree

2 files changed

+25
-6
lines changed

2 files changed

+25
-6
lines changed

‎src/backend/executor/nodeTableFuncscan.c

Lines changed: 24 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -164,7 +164,7 @@ ExecInitTableFuncScan(TableFuncScan *node, EState *estate, int eflags)
164164
/* Only XMLTABLE is supported currently */
165165
scanstate->routine=&XmlTableRoutine;
166166

167-
scanstate->perValueCxt=
167+
scanstate->perTableCxt=
168168
AllocSetContextCreate(CurrentMemoryContext,
169169
"TableFunc per value context",
170170
ALLOCSET_DEFAULT_SIZES);
@@ -282,6 +282,16 @@ tfuncFetchRows(TableFuncScanState *tstate, ExprContext *econtext)
282282
oldcxt=MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
283283
tstate->tupstore=tuplestore_begin_heap(false, false,work_mem);
284284

285+
/*
286+
* Each call to fetch a new set of rows - of which there may be very many
287+
* if XMLTABLE is being used in a lateral join - will allocate a possibly
288+
* substantial amount of memory, so we cannot use the per-query context
289+
* here. perTableCxt now serves the same function as "argcontext" does in
290+
* FunctionScan - a place to store per-one-call (i.e. one result table)
291+
* lifetime data (as opposed to per-query or per-result-tuple).
292+
*/
293+
MemoryContextSwitchTo(tstate->perTableCxt);
294+
285295
PG_TRY();
286296
{
287297
routine->InitOpaque(tstate,
@@ -313,15 +323,17 @@ tfuncFetchRows(TableFuncScanState *tstate, ExprContext *econtext)
313323
}
314324
PG_END_TRY();
315325

316-
/* return to original memory context, and clean up */
317-
MemoryContextSwitchTo(oldcxt);
326+
/* clean up and return to original memory context */
318327

319328
if (tstate->opaque!=NULL)
320329
{
321330
routine->DestroyOpaque(tstate);
322331
tstate->opaque=NULL;
323332
}
324333

334+
MemoryContextSwitchTo(oldcxt);
335+
MemoryContextReset(tstate->perTableCxt);
336+
325337
return;
326338
}
327339

@@ -428,7 +440,14 @@ tfuncLoadRows(TableFuncScanState *tstate, ExprContext *econtext)
428440

429441
ordinalitycol=
430442
((TableFuncScan*) (tstate->ss.ps.plan))->tablefunc->ordinalitycol;
431-
oldcxt=MemoryContextSwitchTo(tstate->perValueCxt);
443+
444+
/*
445+
* We need a short-lived memory context that we can clean up each time
446+
* around the loop, to avoid wasting space. Our default per-tuple context
447+
* is fine for the job, since we won't have used it for anything yet in
448+
* this tuple cycle.
449+
*/
450+
oldcxt=MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
432451

433452
/*
434453
* Keep requesting rows from the table builder until there aren't any.
@@ -493,7 +512,7 @@ tfuncLoadRows(TableFuncScanState *tstate, ExprContext *econtext)
493512

494513
tuplestore_putvalues(tstate->tupstore,tupdesc,values,nulls);
495514

496-
MemoryContextReset(tstate->perValueCxt);
515+
MemoryContextReset(econtext->ecxt_per_tuple_memory);
497516
}
498517

499518
MemoryContextSwitchTo(oldcxt);

‎src/include/nodes/execnodes.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1580,7 +1580,7 @@ typedef struct TableFuncScanState
15801580
FmgrInfo*in_functions;/* input function for each column */
15811581
Oid*typioparams;/* typioparam for each column */
15821582
int64ordinal;/* row number to be output next */
1583-
MemoryContextperValueCxt;/*short lifecontext for value evaluation */
1583+
MemoryContextperTableCxt;/*per-tablecontext */
15841584
Tuplestorestate*tupstore;/* output tuple store */
15851585
}TableFuncScanState;
15861586

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp