Re: Keepalive

On Jun 15, 2024, at 7:25 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

Rui DeSousa <rui.desousa@icloud.com> writes:

Actually, I just tested on it the Linux system.  The keep alive event occurred, the kernel state of the connection went to CLOSE_WAIT and then it was later completely removed from the kernel state; however, my spinner() function is still running with no network connection in the kernel table.

So, keep alive does behave differently between FreeBSD and Linux.  I really do prefer FreeBSD for many reasons.

The behavior you report for Linux is what I'd expect anywhere.
I tried to replicate your results on a freshly-updated FreeBSD 14.1
installation, and could not.  With a purely stock Postgres
configuration, I see the "spinner" query running indefinitely after
the client is killed --- although the kernel does show the server
process's client connection being in CLOSE_WAIT state.  But if I set
client_connection_check_interval to a positive value then the query
kills itself at the next multiple of that time, again as expected.

So I think there is something non-default about your FreeBSD system.
Maybe you'd previously configured it with nonzero
client_connection_check_interval, and then forgot about that?

The alternative is to suppose that that kernel will kill processes
as soon as they have a connection in CLOSE_WAIT state, which would be
quite evil for many purposes and is certainly not a "preferable"
behavior.

regards, tom lane