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Eliminate memory leaks in plperl's spi_prepare() function.
Careless use of TopMemoryContext for I/O function data meant that repeated use of spi_prepare and spi_freeplan would leak memory at the session level, as per report from Christian Schröder. In addition, spi_prepare leaked a lot of transient data within the current plperl function's SPI Proc context, which would be a problem for repeated use of spi_prepare within a single plperl function call; and it wasn't terribly careful about releasing permanent allocations in event of an error, either. In passing, clean up some copy-and-pasteos in query-lookup error messages. Alex Hunsaker and Tom Lane
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+72
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1 file changed

+72
-44
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‎src/pl/plperl/plperl.c‎

Lines changed: 72 additions & 44 deletions
Original file line numberDiff line numberDiff line change
@@ -184,6 +184,7 @@ typedef struct plperl_call_data
184184
typedef struct plperl_query_desc
185185
{
186186
char qname[24];
187+
MemoryContext plan_cxt; /* context holding this struct */
187188
SPIPlanPtr plan;
188189
int nargs;
189190
Oid *argtypes;
@@ -3209,33 +3210,57 @@ plperl_spi_cursor_close(char *cursor)
32093210
SV *
32103211
plperl_spi_prepare(char *query, int argc, SV **argv)
32113212
{
3212-
plperl_query_desc *qdesc;
3213-
plperl_query_entry *hash_entry;
3214-
bool found;
3215-
SPIPlanPtr plan;
3216-
int i;
3217-
3213+
volatile SPIPlanPtr plan = NULL;
3214+
volatile MemoryContext plan_cxt = NULL;
3215+
plperl_query_desc *volatile qdesc = NULL;
3216+
plperl_query_entry *volatile hash_entry = NULL;
32183217
MemoryContext oldcontext = CurrentMemoryContext;
32193218
ResourceOwner oldowner = CurrentResourceOwner;
3219+
MemoryContext work_cxt;
3220+
bool found;
3221+
int i;
32203222

32213223
check_spi_usage_allowed();
32223224

32233225
BeginInternalSubTransaction(NULL);
32243226
MemoryContextSwitchTo(oldcontext);
32253227

3226-
/************************************************************
3227-
* Allocate the new querydesc structure
3228-
************************************************************/
3229-
qdesc = (plperl_query_desc *) malloc(sizeof(plperl_query_desc));
3230-
MemSet(qdesc, 0, sizeof(plperl_query_desc));
3231-
snprintf(qdesc->qname, sizeof(qdesc->qname), "%p", qdesc);
3232-
qdesc->nargs = argc;
3233-
qdesc->argtypes = (Oid *) malloc(argc * sizeof(Oid));
3234-
qdesc->arginfuncs = (FmgrInfo *) malloc(argc * sizeof(FmgrInfo));
3235-
qdesc->argtypioparams = (Oid *) malloc(argc * sizeof(Oid));
3236-
32373228
PG_TRY();
32383229
{
3230+
CHECK_FOR_INTERRUPTS();
3231+
3232+
/************************************************************
3233+
* Allocate the new querydesc structure
3234+
*
3235+
* The qdesc struct, as well as all its subsidiary data, lives in its
3236+
* plan_cxt. But note that the SPIPlan does not.
3237+
************************************************************/
3238+
plan_cxt = AllocSetContextCreate(TopMemoryContext,
3239+
"PL/Perl spi_prepare query",
3240+
ALLOCSET_SMALL_MINSIZE,
3241+
ALLOCSET_SMALL_INITSIZE,
3242+
ALLOCSET_SMALL_MAXSIZE);
3243+
MemoryContextSwitchTo(plan_cxt);
3244+
qdesc = (plperl_query_desc *) palloc0(sizeof(plperl_query_desc));
3245+
snprintf(qdesc->qname, sizeof(qdesc->qname), "%p", qdesc);
3246+
qdesc->plan_cxt = plan_cxt;
3247+
qdesc->nargs = argc;
3248+
qdesc->argtypes = (Oid *) palloc(argc * sizeof(Oid));
3249+
qdesc->arginfuncs = (FmgrInfo *) palloc(argc * sizeof(FmgrInfo));
3250+
qdesc->argtypioparams = (Oid *) palloc(argc * sizeof(Oid));
3251+
MemoryContextSwitchTo(oldcontext);
3252+
3253+
/************************************************************
3254+
* Do the following work in a short-lived context so that we don't
3255+
* leak a lot of memory in the PL/Perl function's SPI Proc context.
3256+
************************************************************/
3257+
work_cxt = AllocSetContextCreate(CurrentMemoryContext,
3258+
"PL/Perl spi_prepare workspace",
3259+
ALLOCSET_DEFAULT_MINSIZE,
3260+
ALLOCSET_DEFAULT_INITSIZE,
3261+
ALLOCSET_DEFAULT_MAXSIZE);
3262+
MemoryContextSwitchTo(work_cxt);
3263+
32393264
/************************************************************
32403265
* Resolve argument type names and then look them up by oid
32413266
* in the system cache, and remember the required information
@@ -3256,7 +3281,7 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
32563281
getTypeInputInfo(typId, &typInput, &typIOParam);
32573282

32583283
qdesc->argtypes[i] = typId;
3259-
perm_fmgr_info(typInput, &(qdesc->arginfuncs[i]));
3284+
fmgr_info_cxt(typInput, &(qdesc->arginfuncs[i]), plan_cxt);
32603285
qdesc->argtypioparams[i] = typIOParam;
32613286
}
32623287

@@ -3280,6 +3305,17 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
32803305
elog(ERROR, "SPI_keepplan() failed");
32813306
qdesc->plan = plan;
32823307

3308+
/************************************************************
3309+
* Insert a hashtable entry for the plan.
3310+
************************************************************/
3311+
hash_entry = hash_search(plperl_active_interp->query_hash,
3312+
qdesc->qname,
3313+
HASH_ENTER, &found);
3314+
hash_entry->query_data = qdesc;
3315+
3316+
/* Get rid of workspace */
3317+
MemoryContextDelete(work_cxt);
3318+
32833319
/* Commit the inner transaction, return to outer xact context */
32843320
ReleaseCurrentSubTransaction();
32853321
MemoryContextSwitchTo(oldcontext);
@@ -3295,16 +3331,21 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
32953331
{
32963332
ErrorData *edata;
32973333

3298-
free(qdesc->argtypes);
3299-
free(qdesc->arginfuncs);
3300-
free(qdesc->argtypioparams);
3301-
free(qdesc);
3302-
33033334
/* Save error info */
33043335
MemoryContextSwitchTo(oldcontext);
33053336
edata = CopyErrorData();
33063337
FlushErrorState();
33073338

3339+
/* Drop anything we managed to allocate */
3340+
if (hash_entry)
3341+
hash_search(plperl_active_interp->query_hash,
3342+
qdesc->qname,
3343+
HASH_REMOVE, NULL);
3344+
if (plan_cxt)
3345+
MemoryContextDelete(plan_cxt);
3346+
if (plan)
3347+
SPI_freeplan(plan);
3348+
33083349
/* Abort the inner transaction */
33093350
RollbackAndReleaseCurrentSubTransaction();
33103351
MemoryContextSwitchTo(oldcontext);
@@ -3326,14 +3367,8 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
33263367
PG_END_TRY();
33273368

33283369
/************************************************************
3329-
* Insert a hashtable entry for the plan and return
3330-
* the key to the caller.
3370+
* Return the query's hash key to the caller.
33313371
************************************************************/
3332-
3333-
hash_entry = hash_search(plperl_active_interp->query_hash, qdesc->qname,
3334-
HASH_ENTER, &found);
3335-
hash_entry->query_data = qdesc;
3336-
33373372
return cstr2sv(qdesc->qname);
33383373
}
33393374

@@ -3368,16 +3403,14 @@ plperl_spi_exec_prepared(char *query, HV *attr, int argc, SV **argv)
33683403
/************************************************************
33693404
* Fetch the saved plan descriptor, see if it's o.k.
33703405
************************************************************/
3371-
33723406
hash_entry = hash_search(plperl_active_interp->query_hash, query,
33733407
HASH_FIND, NULL);
33743408
if (hash_entry == NULL)
33753409
elog(ERROR, "spi_exec_prepared: Invalid prepared query passed");
33763410

33773411
qdesc = hash_entry->query_data;
3378-
33793412
if (qdesc == NULL)
3380-
elog(ERROR, "spi_exec_prepared: panic - plperl query_hash value vanished");
3413+
elog(ERROR, "spi_exec_prepared: plperl query_hash value vanished");
33813414

33823415
if (qdesc->nargs != argc)
33833416
elog(ERROR, "spi_exec_prepared: expected %d argument(s), %d passed",
@@ -3509,12 +3542,11 @@ plperl_spi_query_prepared(char *query, int argc, SV **argv)
35093542
hash_entry = hash_search(plperl_active_interp->query_hash, query,
35103543
HASH_FIND, NULL);
35113544
if (hash_entry == NULL)
3512-
elog(ERROR, "spi_exec_prepared: Invalid prepared query passed");
3545+
elog(ERROR, "spi_query_prepared: Invalid prepared query passed");
35133546

35143547
qdesc = hash_entry->query_data;
3515-
35163548
if (qdesc == NULL)
3517-
elog(ERROR, "spi_query_prepared: panic - plperl query_hash value vanished");
3549+
elog(ERROR, "spi_query_prepared: plperl query_hash value vanished");
35183550

35193551
if (qdesc->nargs != argc)
35203552
elog(ERROR, "spi_query_prepared: expected %d argument(s), %d passed",
@@ -3619,12 +3651,12 @@ plperl_spi_freeplan(char *query)
36193651
hash_entry = hash_search(plperl_active_interp->query_hash, query,
36203652
HASH_FIND, NULL);
36213653
if (hash_entry == NULL)
3622-
elog(ERROR, "spi_exec_prepared: Invalid prepared query passed");
3654+
elog(ERROR, "spi_freeplan: Invalid prepared query passed");
36233655

36243656
qdesc = hash_entry->query_data;
3625-
36263657
if (qdesc == NULL)
3627-
elog(ERROR, "spi_exec_freeplan: panic - plperl query_hash value vanished");
3658+
elog(ERROR, "spi_freeplan: plperl query_hash value vanished");
3659+
plan = qdesc->plan;
36283660

36293661
/*
36303662
* free all memory before SPI_freeplan, so if it dies, nothing will be
@@ -3633,11 +3665,7 @@ plperl_spi_freeplan(char *query)
36333665
hash_search(plperl_active_interp->query_hash, query,
36343666
HASH_REMOVE, NULL);
36353667

3636-
plan = qdesc->plan;
3637-
free(qdesc->argtypes);
3638-
free(qdesc->arginfuncs);
3639-
free(qdesc->argtypioparams);
3640-
free(qdesc);
3668+
MemoryContextDelete(qdesc->plan_cxt);
36413669

36423670
SPI_freeplan(plan);
36433671
}

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