Install Apps - LimeSurvey

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#1 Wed, 04/01/2009 - 04:53
kenlyle

Install Apps - LimeSurvey

dependencies problem detected : Limesurvey does not work when using fcgid mode for executing PHP scripts.

What? Maybe this should be in the Newb forum, but it seems advanced to me.

Thanks, K

Wed, 04/01/2009 - 04:57
andreychek

Howdy,

There's 3 different ways PHP can be running -- either as mod_php, fcgid, or plain 'ol CGI.

It sounds like yours is setup using fcgid.

And apparently, for whatever reason, that doesn't work well ;-)

You can change that for your one domain by going into Virtualmin, clicking the domain from the drop-down on the top-left, and go into Server Configuration -> Website Options.

From there, try changing "PHP script execution mode" to "CGI".
-Eric

Wed, 04/01/2009 - 07:22 (Reply to #2)
kenlyle

Thanks!

I made this change on the one VS, and then was able to install Limesurvey. Cool!

I went looking in Server Templates to see whether I could make PHP as CGI a default, and am not seeing it. Can it be done? and how?

Thanks,
Ken

Wed, 04/01/2009 - 07:24 (Reply to #3)
andreychek

Hi Ken,

That option is in the Server Templates under Apache Website, and is called "Default PHP execution mode".
-Eric

Wed, 04/01/2009 - 08:05 (Reply to #4)
Joe
Joe's picture

<div class='quote'>I went looking in Server Templates to see whether I could make PHP as CGI a default, and am not seeing it.</div>

Unless you plan to run LimeSurvey in every virtual server, I wouldn't recommend this path. CGI is slower and more resource intensive than mod_fcgid. And, as far as I know, LimeSurvey is the only PHP app available in Install Scripts that requires CGI mode.

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Wed, 04/01/2009 - 07:42 (Reply to #5)
kenlyle

THANKS!

There were so many options on that page, my eyes had glazed over a bit, apparently.

K

Wed, 04/01/2009 - 09:17 (Reply to #6)
kenlyle

Wow, Thanks!

This is the question that immediately occurred to me, but that I forgot to ask.

How much worse is it?

Maybe someone can help me interpret http://2bits.com/articles/apache-fcgid-acceptable-performance-and-better...

Thanks,
K

Wed, 04/01/2009 - 09:22 (Reply to #7)
andreychek

It's largely going to depend on how busy your sites are, and what sort of hardware you're running.

The best suggestion I can offer is never to take anyone's word for it -- you now know how to change a site to CGI -- take a PHP script, and load it in a Virtual Server running CGI, and another in fcgid, and try it out!

Do some benchmarking with &quot;ab&quot; or the like.

No one can know better than you as to whether it would be okay on your system :-)

The site you linked to actually compares mod_php vs fcgid, which isn't what you're after -- you need to compare cgi and fcgid.
-Eric

Wed, 04/01/2009 - 10:00 (Reply to #8)
Joe
Joe's picture

As Eric mentioned, comparing mod_php to fcgid in this context isn't useful. But the basic premise of those benchmark results is that mod_fcgid is a bit more resource friendly than mod_php; i.e. less memory used, fewer processes spawned, and overall more friendly to others on the system. Performance-wise, I've always understood mod_php and mod_fcgid+PHP to be roughly the same. But, if you can use less memory and fewer processes, that's a big win, anyway.

CGI, on the other hand, is a whole other can of worms. It definitely is slower (and probably worse than mod_php with regard to memory and other resource usage). How much so depends on your applications and workload. Some folks would never notice the difference. But on a heavily loaded site, it could be the difference between a nice experience and an intolerable one.

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Wed, 04/01/2009 - 13:31 (Reply to #9)
kenlyle

Thanks!

Wed, 04/01/2009 - 14:01 (Reply to #10)
c_schmitz

Hello Joe,

I guess we had some kind of contact before, but I am not sure.
I am the project leader of LimeSurvey and I am wondering about the sentence

'And, as far as I know, LimeSurvey is the only PHP app available in Install Scripts that requires CGI mode. '

I am wondering:

Why? What limitation does LimeSurvey have, that it has to run in that specific mode?

Luckily kenlyle did notify us and so I am here seeking for information ;).

Best regards

Carsten Schmitz
LimeSurvey Project Lead

Wed, 04/01/2009 - 14:05 (Reply to #11)
Joe
Joe's picture

I have no idea! I'm vaguely recalling that someone filed a ticket about a LimeSurvey install, and the only solution Jamie could come up with that fixed the particular issue was switching to mod_php or CGI. I can't actually find that ticket now, but I'd be happy for that diagnosis to be wrong.

I've asked Jamie to chime in here, as he may have a better recollection of why LimeSurvey has this somewhat odd requirement in Install Scripts.

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Wed, 04/01/2009 - 14:29 (Reply to #12)
Joe
Joe's picture

When I wrote the Limesurvey installer originally, I was unable to login to limesurvey when using fcgid mode.
However, testing it again now reveals that it works fine! So I'll remove that
requirement in future Virtualmin releases.

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Thu, 04/02/2009 - 01:59
c_schmitz

Hello Jamie,!

Thank you for the feedback! I am glad it is resolved (whatever it caused).

Best regards

Carsten Schmitz
LimeSurvey Project Lead

Thu, 04/02/2009 - 11:17 (Reply to #14)
Joe
Joe's picture

And thank you, Carsten, for pinging us on this issue. Our level of knowledge about any of our supported Install Scripts is very low, as there are so many of them at this point. We greatly appreciate it when folks who actually understand them are around to keep us moving in the right direction and following best practices.

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