[rt-users] Re: Performance Issues

[Ruslan U. Zakirov]

Bob Goldstein wrote:
>>Ruslan U. Zakirov <cubic at acronis.ru> wrote:
>>
>>>Guys. Please. Fill this info on wiki.bestpractical.com with descriptions 
>>>and may be links to archive of this or other similar discussion.
>>>
>>>'-processes X' is not optional record in config but required IMHO. When 
>>>you run only _one_ FastCGI process then it's something like running RT 
>>>under mod_perl in 'httpd -X' mode.
>>
>>Another data point: this helped us greatly.  I added the following to the
>>FastCGIFAQ page, and changed the examples below to match -- can someone
>>fact-check me please?
>>
>>   Q: Why is RT under FastCGI so sloooooooow? When using a progressive-rendin
>>g
>>   browser like Firefox I see the entries appear slowly, one at a time, but
>>   the server doesn't appear to be overloaded and the database is not large.
>>
>>   A: You might only have spawned one mason_handler.fcgi, which would cause
>>   all the httpd processes to block, waiting for it to service them. Make sur
>>e
>>   you use an appropriate "-processes X" option in your FastCgiServer
>>   directive, as shown below. You should have as many mason_handler.fcgi
>>   processes as the nominal number of httpds that are usually running
>>   (StartServers <= "-processes" <= MaxSpareServers) 
As I wrote in FAQ other FastCGI guys had reported that one FastCGI 
process can handle 2-3 httpd process well.

Also this should be mentioned on FastCGIConfiguration wiki page.
> 
> 
>     Are you sure about your recommended number of processes? My
>     understanding is that apache spawns StartServers processes
>     when it launches, and that it continues to spawn processes,
>     keeping between MinSpareServices and MaxSpareServers idle,
>     just to handle any unanticipated surge. It's quite possible
>     to have MaxSpareServers=10, yet to have 100 running processes
>     on a loaded server.
> 
>     Too many fcgi processes would eat memory, too few won't perform.
> 
>     I also have a question about your explantion.  I think it's
>     true that if my request is being processed by the only
>     fcgi process, yours will block until mine is complete.
>     But why would my request, once processing starts, be slow?
>     I would have thought the symptom would be a long latency
>     followed by a fast full page.
Not right. Nobody say that RT is fast like a bullet. And if avg request 
time 3 seconds it does make sense if you wait 3 or 6(2 concurent 
requests) or 9 or ...

Also you can wait even more if requests for images(static images and 
other files) goes through FastCGI/mod_perl too :) As I remember this 
topic is highlighted on ML only.

> 
>         bobg