Re: Parallel scan with SubTransGetTopmostTransaction assert coredump

> To: Pengchengliu <pengchengliu@tju.edu.cn>
> Cc: Greg Nancarrow <gregn4422@gmail.com>; Andres Freund <andres@anarazel.de>; PostgreSQL-development
<pgsql-hackers@postgresql.org>
> Subject: Re: Re: Parallel scan with SubTransGetTopmostTransaction assert coredump

> I've also seen the reports of the same Assert(TransactionIdFollowsOrEquals(xid, TransactionXmin)) with a subsequent
crashin a parallel worker in PostgreSQL v11-based 
 
> build, Though I was unable to investigate deeper and reproduce the issue. The details above in the thread make me
thinkit is a real and long-time-persistent error that is 
 
> surely worth to be fixed.

I followed Liu's reproduce steps and successfully reproduce it in about half an hour running.
My compile option is : " ./configure --enable-cassert --prefix=/home/pgsql".

After applying greg-san's change, the coredump did not happened in two hour(it is still running).
Note, I have not taken a deep look into the change, just provide some test information in advance.

Best regards,
houzj