Prevent long-term memory leakage in autovacuum launcher.
get_database_list() failed to restore the caller's memory context,
instead leaving current context set to TopMemoryContext which is
how CommitTransactionCommand() leaves it. The callers both think
they are using short-lived contexts, for the express purpose of
not having to worry about cleaning up individual allocations.
The net effect therefore is that supposedly short-lived allocations
could accumulate indefinitely in the launcher's TopMemoryContext.
Although this has been broken for a long time, it seems we didn't
have any obvious memory leak here until v15's rearrangement of the
stats logic. I (tgl) am not entirely convinced that there's no
other leak at all, though, and we're surely at risk of adding one
in future back-patched fixes. So back-patch to all supported
branches, even though this may be only a latent bug in pre-v15.
Reid Thompson
Discussion: https://postgr.es/m/972a4e12b68b0f96db514777a150ceef7dcd2e0f.camel@crunchydata.com
Branch
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REL_15_STABLE
Details
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https://git.postgresql.org/pg/commitdiff/0c599e748f2c81e415bb39567c4fd40a6bc64815
Modified Files
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src/backend/postmaster/autovacuum.c | 3 +++
1 file changed, 3 insertions(+)