Attached is a simple patch that fixes a minor problem in PL/Python: in PLy_spi_execute_plan(), we invoke the input function for a Postgres data type. If that function elog's (which is quite possible), PL/Python leaks references to two temporary Python objects. The fix seems easy, albeit a bit ugly: the reference count on one of the temporary objects can be decremented before calling the function. A pointer that points into the second object is passed to the input function itself, so we have to PG_CATCH() the elog and decrement the refcount then.

Since the problem might actually occur in practice and the fix seems to have little chance of inducing a regression, I'm thinking of applying this to both HEAD and back branches. Barring any objections I'll do that later today or early tomorrow.


-Neil
Index: src/pl/plpython/plpython.c
===================================================================
RCS file: /Users/neilc/postgres/cvs_root/pgsql/src/pl/plpython/plpython.c,v
retrieving revision 1.67
diff -c -r1.67 plpython.c
*** src/pl/plpython/plpython.c	26 Dec 2005 04:28:48 -0000	1.67
--- src/pl/plpython/plpython.c	29 Dec 2005 16:49:54 -0000
***************
*** 2,8 ****
   * plpython.c - python as a procedural language for PostgreSQL
   *
   * This software is copyright by Andrew Bosma
!  * but is really shameless cribbed from pltcl.c by Jan Weick, and
   * plperl.c by Mark Hollomon.
   *
   * The author hereby grants permission to use, copy, modify,
--- 2,8 ----
   * plpython.c - python as a procedural language for PostgreSQL
   *
   * This software is copyright by Andrew Bosma
!  * but is really shameless cribbed from pltcl.c by Jan Wieck, and
   * plperl.c by Mark Hollomon.
   *
   * The author hereby grants permission to use, copy, modify,
***************
*** 1996,2002 ****
  	int			i,
  				rv;
  	PLyPlanObject *plan;
- 	char	   *nulls;
  	MemoryContext oldcontext;
  
  	if (list != NULL)
--- 1996,2001 ----
***************
*** 2018,2024 ****
  	if (nargs != plan->nargs)
  	{
  		char	   *sv;
- 
  		PyObject   *so = PyObject_Str(list);
  
  		if (!so)
--- 2017,2022 ----
***************
*** 2036,2048 ****
  	oldcontext = CurrentMemoryContext;
  	PG_TRY();
  	{
! 		nulls = palloc(nargs * sizeof(char));
  
  		for (i = 0; i < nargs; i++)
  		{
  			PyObject   *elem,
  					   *so;
- 			char	   *sv;
  
  			elem = PySequence_GetItem(list, i);
  			if (elem != Py_None)
--- 2034,2045 ----
  	oldcontext = CurrentMemoryContext;
  	PG_TRY();
  	{
! 		char	   *nulls = palloc(nargs * sizeof(char));
  
  		for (i = 0; i < nargs; i++)
  		{
  			PyObject   *elem,
  					   *so;
  
  			elem = PySequence_GetItem(list, i);
  			if (elem != Py_None)
***************
*** 2051,2070 ****
  				if (!so)
  					PLy_elog(ERROR, "function \"%s\" could not execute plan",
  							 PLy_procedure_name(PLy_curr_procedure));
! 				sv = PyString_AsString(so);
  
! 				/*
! 				 * FIXME -- if this elogs, we have Python reference leak
! 				 */
! 				plan->values[i] =
! 					FunctionCall3(&(plan->args[i].out.d.typfunc),
! 								  CStringGetDatum(sv),
! 							ObjectIdGetDatum(plan->args[i].out.d.typioparam),
! 								  Int32GetDatum(-1));
  
! 				Py_DECREF(so);
! 				Py_DECREF(elem);
  
  				nulls[i] = ' ';
  			}
  			else
--- 2048,2073 ----
  				if (!so)
  					PLy_elog(ERROR, "function \"%s\" could not execute plan",
  							 PLy_procedure_name(PLy_curr_procedure));
! 				Py_DECREF(elem);
  
! 				PG_TRY();
! 				{
! 					char *sv = PyString_AsString(so);
  
! 					plan->values[i] =
! 						FunctionCall3(&(plan->args[i].out.d.typfunc),
! 									  CStringGetDatum(sv),
! 								ObjectIdGetDatum(plan->args[i].out.d.typioparam),
! 									  Int32GetDatum(-1));
! 				}
! 				PG_CATCH();
! 				{
! 					Py_DECREF(so);
! 					PG_RE_THROW();
! 				}
! 				PG_END_TRY();
  
+ 				Py_DECREF(so);
  				nulls[i] = ' ';
  			}
  			else
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