Re: Parallel pg_dump's error reporting doesn't work worth squat

At Thu, 2 Jun 2016 12:17:11 -0400, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote in <20160602161711(dot)GA239156(at)alvherre(dot)pgsql>
> Tom Lane wrote:
> > Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> writes:
> > > Apart from the invalid snapshot problem, I looked the patch
> > > previously mentioned mainly for Windows.
> >
> > Thanks for looking!
> >
> > > Even though the threads started by beginthread cannot be
> > > terminated cleanly from outside, but the whole process will soon
> > > terminate anyway, so we could use TreminateThread. This seems
> > > working. (Attached patch)
> >
> > Seems reasonable to me; I was unhappy about the lack of any direct
> > equivalent to the child SIGTERMs that the Unix code does.

For sure, any of the "dangers" of TerminateThread don't matter
for this case.

https://msdn.microsoft.com/en-us/em-us/library/windows/desktop/ms686717(v=vs.85).aspx

> If the target thread owns a critical section, the critical
> section will not be released.
>
> If the target thread is allocating memory from the heap, the heap
> lock will not be released.
>
> If the target thread is executing certain kernel32 calls when it
> is terminated, the kernel32 state for the thread's process could
> be inconsistent.
>
> If the target thread is manipulating the global state of a shared
> DLL, the state of the DLL could be destroyed, affecting other
> users of the DLL.

> Given this testing, it's clear that the timeout on select() is useless;
> we could get rid of it in vacuumdb.c too. I'll post a patch later.

Agreed. Command pipes may be in blocking mode for the case.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center