[ic] How to determine cause of load spikes.

Bill Carr bill at worldwideimpact.com
Sat Nov 4 13:08:14 EST 2006


On Nov 4, 2006, at 11:19 AM, ic at 3edge.com wrote:

> DB writes:
>> I'm running IC 5.4.1 using a mysql database of about 500,000 items  
>> on a
>> dual Xeon box with 4GB of RAM. Once in awhile I'll notice the site
>> become sluggish. During these periods the cpu load is always fairly
>> high.  I suspect these events are caused by an inefficient search  
>> on the
>> large products database. See below for an example 'top' output  
>> during a
>> recent event: top - 11:26:03 up 31 days, 20:50,  1 user,  load  
>> average: 1.13, 0.97, 0.67
>> Tasks: 227 total,   2 running, 223 sleeping,   0 stopped,   2 zombie
>> Cpu(s): 25.1% us,  0.1% sy,  0.0% ni, 74.9% id,  0.0% wa,  0.0%  
>> hi,  0.0% si
>> Mem:   4040624k total,  3568748k used,   471876k free,   118736k  
>> buffers
>> Swap:  2031608k total,     8664k used,  2022944k free,  1453916k  
>> cached   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME 
>> +  COMMAND
>> 26248 inter     25   0 1367m 1.2g 1880 R  100 32.4   0:47.43  
>> interchange So I can identify the offending process ID, but how  
>> can I determine what
>> this process is doing to cause such a load? If I can determine what
>> search is being run or which of my pages is being accessed then I can
>> probably correct the problem. Bumping the RAM up to 4GB has  
>> drastically reduced the extent of the
>> problem, but I want to find and correct the real cause of the  
>> trouble. DB
>
> Have you tried:
> strace -p 26248
> Perhaps that gives you some more insight?
If you suspect a slow query then try turning on the mysql slow query  
log. Let it run for a few days then optimize your most frequent and  
slowest queries.

Bill Carr
Bottlenose - Wine & Spirits eBusiness Specialists
(877) 857-6700



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