Tom Lane <t...@sss.pgh.pa.us> writes: > Simon Riggs <si...@2ndquadrant.com> writes: >> Can we add something to memory contexts to make this fail every time? > > No, not really. AFAICS the reason for Alvaro not seeing it must be that > on his machine the new transaction happens to allocate its > TopTransactionContext control block right in the same place where the > old one was. > > We could have a debugging mode in which pfree'd space is never recycled > for reuse (just filled with 0xdeadbeef or whatever and left to sit).
Hm, I wonder how much more practical it would be if we recycled it but offset the pointer by maxalign. We would waste 4/8 bytes per palloc/free cycle instead of the whole chunk. (Whether palloc could actually do this would be another question, there are lots of allocator algorithms that wouldn't be able to, I think.) If we had a more formalized save_memory_context()/restore_memory_context() which gave you more than just a pointer we could do better for this particular case. save_memory_context() could hand you a struct with a pointer as well as some sanity check values about the context you're saving. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's On-Demand Production Tuning -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
