Re: retry shm attach for windows (WAS: Re: [HACKERS] OK, so culicidaeis *still* broken)

On 02/06/17 15:37, Amit Kapila wrote:
> On Thu, Jun 1, 2017 at 10:36 PM, Petr Jelinek
> <petr.jelinek@2ndquadrant.com> wrote:
>> On 01/06/17 15:25, Tom Lane wrote:
>>> Robert Haas <robertmhaas@gmail.com> writes:
>>>> So, are you going to, perhaps, commit this?  Or who is picking this up?
>>>
>>>> /me knows precious little about Windows.
>>>
>>> I'm not going to be the one to commit this either, but seems like someone
>>> should.
>>>
>>
>> The new code does not use any windows specific APIs or anything, it just
>> adds retry logic for reattaching when we do EXEC_BACKEND which seems to
>> be agreed way of solving this. I do have couple of comments about the
>> code though.
>>
>> The new parameter retry_count in PGSharedMemoryReAttach() seems to be
>> only used to decide if to log reattach issues so that we don't spam log
>> when retrying, but this fact is not mentioned anywhere.
>>
> 
> No, it is to avoid calling free of memory which is not reserved on
> retry.  See the comment:
> + * On the first try, release memory region reservation that was made by
> + * the postmaster.
> 
> Are you referring to the same function in sysv_shm.c, if so probably I
> can say refer the same API in win32_shmem.c or maybe add a similar
> comment there as well?
> 

Yeah something like that would help, but my main confusion comes from
the fact that there is counter (and even named as such) but only
relevant difference is 0 and not 0. I'd like mention of that mainly
since I was confused by that on the first read.

--  Petr Jelinek                  http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training &
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