Re: issue with meson builds on msys2

Hi,

On 2023-05-15 15:30:28 -0700, Andres Freund wrote:

As soon as either the pg_ctl for the start, or the whole bash invocation, has
stdin redirected, the problem vanishes.

For a moment I thought this could be related to InheritStdHandles() - but no,
it doesn't make a difference.

There's loads of handles referencing cygwin alive in pg_ctl.

Based on difference in strace output for bash -c "pg_ctl stop" for the case
where start redirected stdin (#1) and where not (#2), it looks like some part
of msys / cygwin sees that stdin is alive when preparing to execute "pg_ctl
stop", and then runs into trouble.

The way we start the child process on windows makes the use of cmd.exe for
redirection pretty odd.


I couldn't trivially reproduce this with a much simpler case (just nohup
sleep). Perhaps it's dependent on a wrapper cmd or such.

I don't know where this all leaves us. It's still more than odd that the start works fine and the stop doesn't.

This piece of code has worked happily for years. It's only a recent installation or update of msys2 that's made the problem appear.

I have implemented a workaround where IPC::Run is available - that means a little extra one-off work for people using msys2, but it's not a huge burden. Beyond that I don't really want to spend a lot more energy on it.

I suppose the alternative would be to change the way the buildfarm calls pg_ctl stop. Do you have a concrete suggestion for that?

cheers

andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com