On Wed, Oct 21, 2020 at 3:02 PM Bharath Rupireddy < bharath.rupireddyforpostg...@gmail.com> wrote:
> Hi, > > Currently pg_terminate_backend(), sends SIGTERM to the backend process but > doesn't ensure it's exit. There are chances that backends still are > running(even after pg_terminate_backend() is called) until the interrupts > are processed(using ProcessInterrupts()). This could cause problems > especially in testing, for instance in a sql file right after > pg_terminate_backend(), if any test case depends on the backend's > non-existence[1], but the backend is not terminated. As discussed in [1], > we have wait_pid()(see regress.c and sql/dblink.sql), but it's not usable > across the system. In [1], we thought it would be better to have functions > ensuring the backend's exit on the similar lines of pg_terminate_backend(). > > I propose to have two functions: > > 1. pg_terminate_backend_and_wait() -- which sends SIGTERM to the backend > and wait's until it's exit. > I think it would be nicer to have a pg_terminate_backend(pid, wait=false), so a function with a second parameter which defaults to the current behaviour of not waiting. And it might be a good idea to also give it a timeout parameter? > 2. pg_wait_backend() -- which waits for a given backend process. Note that > this function has to be used carefully after pg_terminate_backend(), if > used on a backend that's not ternmited it simply keeps waiting in a loop. > It seems this one also very much would need a timeout value. And surely we should show some sort of wait event when it's waiting. -- Magnus Hagander Me: https://www.hagander.net/ <http://www.hagander.net/> Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>
