Le lun. 29 nov. 2021 à 20:39, Tom Lane <t...@sss.pgh.pa.us> a écrit :
> Guillaume Lelarge <guilla...@lelarge.info> writes: > > I've tried Justin's patch but it didn't help with my memory allocation > > issue. FWIW, I attach the patch I used in v14. > > [ looks closer ... ] Ah, that patch is a bit buggy: it fails to do the > right thing in the cases where the loop does a "continue". The attached > revision seems to behave properly. > > I still see a small leakage, which I think is due to accumulation of > pending sinval messages for the catalog updates. I'm curious whether > that's big enough to be a problem for Guillaume's use case. (We've > speculated before about bounding the memory used for pending sinval > in favor of just issuing a cache reset when the list would be too > big. But nobody's done anything about it, suggesting that people > seldom have a problem in practice.) > > I've tried your patch with my test case. It still uses a lot of memory. Actually even more. I have this with the log_statement_stats: 1185072 kB max resident size And I have this with the log-memory-contexts function: LOG: Grand total: 1007796352 bytes in 320 blocks; 3453512 free (627 chunks); 1004342840 used Contrary to Justin's patch, the shdepReassignOwned doesn't seem to be used. I don't get any shdepReassignOwned line in the log file. I tried multiple times to avoid any mistake on my part, but got same result. >> DROP OWNED BY likely has similar issues. > > > Didn't try it, but it wouldn't be a surprise. > > I tried just changing the REASSIGN to a DROP in Justin's example, > and immediately hit > > ERROR: out of shared memory > HINT: You might need to increase max_locks_per_transaction. > > thanks to the per-object locks we try to acquire. So I'm not > sure that the DROP case can reach an interesting amount of > local memory leaked before it runs out of lock-table space. > > I've hit the same issue when I tried my ALTER LARGE OBJECT workaround in one transaction. -- Guillaume.
