Re: There's some sort of race condition with the new FSM stuff - Mailing list pgsql-hackers

From Tom Lane
Subject Re: There's some sort of race condition with the new FSM stuff
Date
Msg-id 12687.1224013996@sss.pgh.pa.us
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In response to Re: There's some sort of race condition with the new FSM stuff  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: There's some sort of race condition with the new FSM stuff
List pgsql-hackers
Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> Zdenek Kotala wrote:
>> Tom Lane napsal(a):
>>> Hmm ... AFAICS this mistake would mean that no forknum field of the
>>> requests[] array ever gets set at all, so they would stay at whatever
>>> the virgin value in the shmem segment had been.  Perhaps Solaris doesn't
>>> guarantee that a shared memory block starts out as zeroes?  
>> 
>> For security reason any OS should clean memory pages before process 
>> first touches them.

> Yeah. But it doesn't necessarily need to fill them with zeros, any 
> garbage will do.

Yeah, but the observed symptoms seem to indicate that the fill is mostly
zeroes with a very occasional one.  This seems less than probable.

The only theory I've thought of that seems to fit the facts is that
someplace we have a wild store that is clobbering that particular word.
Which is a pretty unpleasant thought.
        regards, tom lane


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