Re: The value of direct inspection (was: Re: --initdb)

[Tony Nelson <tonynelson georgeanelson com>]

At 7:31 AM -0500 12/4/06, James Olin Oden wrote:
>> >With fewer players, concurrent access in rpmdb is likelier to be
>> >"stable" because updates are like daily, not every second.
>>
>> I think you're saying that cron scripts for RPM are bad because 1) they
>> often tempt fate by running at the same time and 2) when they get stuck
>> usually it it
>> isn't noticed for a long time.
>>
>Yes, he is.

OK, got it.

>I've actually experienced this in the RH 9 time frame,
>when rpm had many more issues with dead locks.  Basically, I was
>getting calls where an "upgrade" was hung at around 4:00 in the
>morning.  I finally made the correlation (well really someone hit me
>with a clue bat) that that was the same time the "rpm -qa" cron job
>was running.  In minutes I had a reproducer.  My solution was to turn
>off cron during our upgrades (which is reasonable since you don't want
>random stuff kicking off in the middle of your upgrade).
>
>All that said, what I would take from this if I was going to write a
>cron job that examined the rpm database in anyway, is wire in some way
>of disabling the behavior, and wire in some way to actually tell that
>its doing the query right now.  This allows someone to say, "don't
>look right now", and to tell if the message was received.  Then they
>can merrily do whatever they need to do, without worrying about
>another party accessing the db concurrently.

Don't allow more than one RPM client to run at a time.  Especially don't
/schedule/ two to run at the same time.  OK, thanks.
-- 
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TonyN.:'    The Great Writ     <mailto:tonynelson georgeanelson com>
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