Re: [patch] Cache invalidation for I/O Workers

Hi Alexandre,

Thanks for the patch. I read v1, here are my suggestions.

+ if (msg->id == SHAREDINVALSMGR_ID)
+ {
+ RelFileLocatorBackend rlocator;
+ rlocator.locator = msg->sm.rlocator;
+ rlocator.backend = (msg->sm.backend_hi << 16) | (int) msg->sm.backend_lo;
+ smgrreleaserellocator(rlocator);
+ }

Since 21d9c3ee4ef, smgrreleaserellocator() only closes the fds. The
SMgrRelation
entry stays in the hash table. Backends free those in AtEOXact_SMgr(), but
an
IO worker never runs a transaction, so entries for dropped relations
pile up. The fd leak turns into a memory leak. We had runs into production
issue because of that.

bgwriter and checkpointer have the same problem. They call
smgrdestroyall() once per checkpoint cycle, see the comment in
bgwriter.c. Could the IO worker just do the same every so often? That
is option 1 in the bug report. It needs no sinval slot for up to 32
workers, and it is small enough to backpatch to 18, where
io_method=worker is the default.

The patch also needs a pgindent run.

Thanks,
Shihao