Re[2]: Command-line PHP script CPU usage goes sky-high, stays there--why?

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Hi,

Tuesday, December 11, 2007, 10:01:38 AM, you wrote:
RF> On 10-Dec-07, at 4:42 PM, Tom Rogers wrote:

>>
>> Put a usleep(1000) in the listen while() loop and give the cpu a
>> break.

RF> Good advice, but I've already been doing that. The thing is, when the
RF> script first starts up, the CPU rarely exceeds 30%, even when many  
RF> clients (200+) are simultaneously connected and sending data. When a  
RF> few clients are connected, CPU is typically below 10%. Again, it's  
RF> only after 24-48 hours that, all of a sudden, CPU usage increases by  
RF> 40-50%. And it stays high until I stop the script and restart it.

RF> One question I have though is, is there actually any benefit to using
RF> mysql_pconnect(), since the script simply loops? My understanding is  
RF> that pconnect only benefits if a script would otherwise be using  
RF> mysql_connect repeatedly--and this script doesn't, since it calls  
RF> mysql_[p]connect() just once, in the start tof execution.

RF> ...Rene

I have found pconnect to be a problem (several years ago) and have
never tried it since, it may well be ok now. The most likely cause is
memory consumption on long running php scripts, what does top say?

I have a script which runs from cron and was hammering the system when
it ran and i have had to put the usleep() in the while($result = ..)
loop as there are a few thousand rows. Probably bad design but it
works and I'm loath to touch it :)

One way to solve the memory issue is to have the script started by
inetd, slower but more memory friendly.

Also have a look at memcached to reduce the load a bit.

-- 
regards,
Tom

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