Re: windows shared memory error - Mailing list pgsql-hackers

From Andrew Dunstan
Subject Re: windows shared memory error
Date
Msg-id 49FEE1A1.4070903@dunslane.net
Whole thread Raw
In response to Re: windows shared memory error  (Magnus Hagander <magnus@hagander.net>)
Responses Re: windows shared memory error  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers

Magnus Hagander wrote:
> Tom Lane wrote:
>   
>> Andrew Dunstan <andrew@dunslane.net> writes:
>>     
>>> Now presumably we sleep for 1 sec between the CloseHandle() call and the 
>>> CreateFileMapping() call in that code for a reason.
>>>       
>> I'm not sure.  Magnus never did answer my question about why the sleep
>> and retry was put in at all; it seems not unlikely from here that it
>> was mere speculation.
>>     
>
> It was necessary at the time.
>
> The actual 1 second value was completely random - it fixed all the
> issues on my test VM at the time. I don't recall exactly the details,
> but I do recall having to run a lot of tests before I managed to provoke
> an error, and that with the 1 sec thing i could run it for a day of
> repeated restarts without any errors.
>
>
>   

Well, my untested hypothesis is that the actual time required is 
variable, depending on environmental factors such as machine load. So 
testing repeatedly where such factors are constant might not be good 
enough. That's why I suggested some sort of increasing backoff, in an 
attempt to be adaptive.

cheers

andrew


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