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

From Magnus Hagander
Subject Re: windows shared memory error
Date
Msg-id 49FEF863.5040407@hagander.net
Whole thread Raw
In response to Re: windows shared memory error  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: windows shared memory error  (Andrew Dunstan <andrew@dunslane.net>)
Re: windows shared memory error  (Alvaro Herrera <alvherre@commandprompt.com>)
Re: windows shared memory error  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>> Magnus Hagander wrote:
>>> 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.
> 
> Seems reasonable.
> 
>> 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.
> 
> I still think there's absolutely no evidence suggesting that a variable
> backoff is necessary.  Given how little this code is going to be
> exercised in the real world, how long will it take till we find out
> if you get it wrong?  Use a simple retry loop and be done with it.

+1. Let's keep it as simple as possible for now. I doubt it's actually
dependent on the *failed* call.

Andrew, you want to write up a patch or do you want me to do it?

//Magnus



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