Re: BUG #18031: Segmentation fault after deadlock within VACUUM's parallel worker

Hello Sawada-san,

21.07.2023 11:01, Masahiko Sawada wrote:
> ...
> leading to calling RemoveFromWaitQueue() again. I think we should use
> dclist_delete_from_thoroughly() instead. With the attached patch, the
> issue doesn't happen in my environment.

Thank you for the analysis and the patch! It fixes the issue for me too.

> Another thing I noticed is that the Assert(waitLock) in
> RemoveFromWaitQueue() is useless actually, since we access *waitLock
> before that:

Yeah, I also noticed that, and a simple grep-based script with a little
eyeballing discovered one similar Assert usage:

void
llvm_split_symbol_name(const char *name, char **modname, char **funcname)
{
...
        *funcname = rindex(name, '.');
        (*funcname)++;            /* jump over . */

        *modname = pnstrdup(name + strlen("pgextern."),
                            *funcname - name - strlen("pgextern.") - 1);
        Assert(funcname);

May be it's worth to fix it in passing.

Best regards,
Alexander