On 12/03/2020 00:29, Tom Lane wrote:
Virendra Kumar <viru_7683@xxxxxxxxx> writes:
Can you please back port patch where if a 0 byte packet sent to PG instance (Health Checks), it starts complaining about invalid startup packet and flood the log which increases log size considerably if the health checks are every 3 seconds or something like that.
Patch Requested - https://git.postgresql.org/gitweb/?p=postgresql.git;a=patch;h=342cb650e
We generally don't like to change behavior of back branches without
ironclad agreement that the existing behavior is a bug ... which this
surely isn't. Also, the discussion leading up to that patch specifically
considered and rejected back-patching; so I'm disinclined to overrule
that decision now.
I would suggest that an every-three-second health check is not
appropriate, especially one that is so minimal that it only
detects whether the postmaster is alive.
Does the backend explicitly configure the kernel's TCP accept queue?
Unless Postgres sets it to impractically low numbers, the above test
sounds weak from yet another angle; the postmaster might be "alive" as a
process but completely seized for other reasons: at least in Linux the
TCP accept queue progresses the 3-way handshake so long as the bound
socket's file descriptor is still held, without even waiting for accept().
I'd recommend a better probe that at least sends a startup message and
expects the backend to follow up with the authentication request (no
need to craft messages manually, testing for more abstract
messages/states out of psql or some libpq wrapper would do). Better
still, if credentials/access are available, run a query.
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