Re: Avoid memory leaks during base backups

On Fri, Oct 21, 2022 at 11:34:27AM +0530, Bharath Rupireddy wrote:
> On Fri, Oct 21, 2022 at 12:21 AM Robert Haas <robertmhaas@gmail.com> wrote:
>> On Thu, Oct 20, 2022 at 1:35 PM Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote:
>>> I think elsewhere in the code we reset dangling pointers either ways -
>>> before or after deleting/resetting memory context. But placing them
>>> before would give us extra safety in case memory context
>>> deletion/reset fails. Not sure what's the best way.
>>
>> I think it's OK to assume that deallocating memory will always
>> succeed, so it doesn't matter whether you do it just before or just
>> after that. But it's not OK to assume that *allocating* memory will
>> always succeed.
>
> Right.

To be exact, it seems to me that tablespace_map and backup_state
should be reset before deleting backupcontext, but the reset of
backupcontext should happen after the fact.

+       backup_state = NULL;
        tablespace_map = NULL;
These two in pg_backup_start() don't matter, do they?  They are
reallocated a couple of lines down.

+    * across. We keep the memory allocated in this memory context less,
What does "We keep the memory allocated in this memory context less"
mean here?
--
Michael