[Pljava-dev] TupleDesc reference leak

Hi,

A customer ran into the issue reported through the bug tracker,
#1010962:
http://pgfoundry.org/tracker/?func=detail&atid=334&aid=1010962&group_id=1000038.
If a PL/Java function takes a ResultSet as argument, you get warnings like:

WARNING: TupleDesc reference leak: TupleDesc 124e120 (139824,-1) still
referenced

Grepping through the source, there seems to be two places where PL/Java
gets a reference to a TupleDesc by calling lookup_rowtype_tupdsc(), but
fails to release it. One is in HeapTupleHeader.c:

> jobject HeapTupleHeader_getTupleDesc(HeapTupleHeader ht)
> {
> return TupleDesc_create(
> lookup_rowtype_tupdesc(
> HeapTupleHeaderGetTypeId(ht),
> HeapTupleHeaderGetTypMod(ht)));
> }

This is the one that's leaking in the test case posted in the bug
tracker. Fortunately, this is easy to fix. TupleDesc_create() creates a
copy of the tuple descriptor, so we just need to release it after the
call. Patch attached.

The other is in Type.c, in Type_fromOid function:

> if(typeClass != 0)
> {
> TupleDesc tupleDesc = lookup_rowtype_tupdesc_noerror(typeId, -1, true);
> type = (Type)UDT_registerUDT(typeClass, typeId, typeStruct, tupleDesc, false);
> JNI_deleteLocalRef(typeClass);
> goto finally;
> }

I'm not sure what to do about that one. UDT_registerUDT() puts the
TupleDesc Reference to a field in the UDT instance it creates. It's not
clear to me what the lifecycle of that instance is. If we just created a
copy of the TupleDesc, would we leak memory? Can the UDT object persist
over transactions, in which case it holds a dangling pointer to the
TupleDesc?

Anyway, please apply the attached patch, at least.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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