Re: Avoid memory leaks during base backups

On Wed, Sep 28, 2022 at 10:19 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> writes:
> > I had the same opinion. Here's what I think - for backup functions, we
> > can have the new memory context child of TopMemoryContext and for
> > perform_base_backup(), we can have the memory context child of
> > CurrentMemoryContext. With PG_TRY()-PG_FINALLY()-PG_END_TRY(), we can
> > delete those memory contexts upon ERRORs. This approach works for us
> > since backup-related code doesn't have any FATALs.
>
> Not following your last point here?  A process exiting on FATAL
> does not especially need to clean up its memory allocations first.
> Which is good, because "backup-related code doesn't have any FATALs"
> seems like an assertion with a very short half-life.

You're right. My bad. For FATALs, we don't need to clean the memory as
the process itself exits.

 * Note: an ereport(FATAL) will not be caught by this construct; control will
 * exit straight through proc_exit().

    /*
     * Perform error recovery action as specified by elevel.
     */
    if (elevel == FATAL)
    {

        /*
         * Do normal process-exit cleanup, then return exit code 1 to indicate
         * FATAL termination.  The postmaster may or may not consider this
         * worthy of panic, depending on which subprocess returns it.
         */
        proc_exit(1);
    }

-- 
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com