On Mon, Jun 26, 2023 at 9:46 AM Yugo NAGATA <nag...@sraoss.co.jp> wrote:
> Hello, > > This attached patch enables pgbench to cancel queries during benchmark. > > Formerly, Ctrl+C during benchmark killed pgbench immediately, but backend > processes executing long queries remained for a while. You can simply > reproduce this problem by cancelling the pgbench running a custom script > executing "SELECT pg_sleep(10)". > > The patch fixes this so that cancel requests are sent for all connections > on > Ctrl+C, and all running queries are cancelled before pgbench exits. > > In thread #0, setup_cancel_handler is called before the loop, the > CancelRequested flag is set when Ctrl+C is issued. In the loop, cancel > requests are sent when the flag is set only in thread #0. SIGINT is > blocked in other threads, but the threads will exit after their query > are cancelled. If thread safety is disabled or OS is Windows, the signal > is not blocked because pthread_sigmask cannot be used. > (I didn't test the patch on WIndows yet, though.) > > I choose the design that the signal handler and the query cancel are > performed only in thread #0 because I wanted to make the behavior as > predicable as possible. However, another design that all thread can > received SIGINT and that the first thread that catches the signal is > responsible to sent cancel requests for all connections may also work. > > Also, the array of CState that contains all clients state is changed to > a global variable so that all connections can be accessed within a thread. > > > +1 I also like the thread #0 handling design. I have NOT reviewed/tested this yet.
