Re: [HACKERS] Re: [HACKERS] Re: [HACKERS] Re: [HACKERS] Windows service is not starting so there’s message in log: FATAL: "could not create shared memory segment “Global/PostgreSQL.851401618”: Permission denied”

On Mon, May 9, 2016 at 4:17 PM, Michael Paquier
<michael(dot)paquier(at)gmail(dot)com> wrote:
> On Tue, Mar 22, 2016 at 1:56 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> So as far as I can see there are two ways to resolve this issue, one is to
>> retry generation of dsm name if CreateFileMapping returns EACCES and second
>> is to append data_dir name to dsm name as the same is done for main shared
>> memory, that will avoid the error to occur. First approach has minor flaw
>> that if CreateFileMapping returns EACCES due to reason other then duplicate
>> dsm name which I am not sure is possible to identify, then we should report
>> error instead try to regenerate the name
>>
>> Robert and or others, can you share your opinion on what is the best way to
>> proceed for this issue.
>
> For my 2c here, the approach using GetSharedMemName to identify the
> origin of a dynamic shared memory segment looks more solid in terms of
> robustness and collision handling. Retrying a segment is never going
> to be completely water-proof.

So, I have been hacking that a bit more and finished with the
attached, which seem to address the issue here. Some of the code paths
of dsm_impl.c are done in such a way that we can fail a dsm allocation
and still continue to move on. I have taken that into account by using
palloc_extended with NO_OOM. palloc instead of malloc is a good fit
anyway to prevent leaks in error code paths.

Thoughts?
--
Michael