Hi all,
We recently upgraded our LimeSurvey install from 1.85 to 1.90 version.
Since then we have experienced massive performance problems.
The system is installed on Win Server 2008 with SQL Express 2005 DB.
As a temporary solution while we try to understand what is happening, our hosting company added an extra CPU for us (virtual machine) and doubled the RAM to 2gb but we've seen DB use of CPU hit 100% again.
We're getting survey responses in the tens, hundreds at most, not thousands.
I can't believe we're the only ones to be experiencing this problem?
A quick and dirty trace of the DB looks like a huge number of cursor calls retrieveing hierarchical sub-question data.
It it possible that the re-design around sub-questions has caused this issue?
Is it possible that the upgrade script has removed or failed to add some critical indexes?
We've obviously going to undertake some major structured performance testing starting with a downgrade back to 1.85 and work up from there but this will take time and in the mean time we're suffering badly!

Any ideas for quick fixes we could try?

Hmm, I have the impression, that whenever those issues come up, that a windows server is involved. Maybe there is an issue with Limesurvey and windows server? (that is just my impression that I got being on the forum quite frequently, but it might be something to look at).

Hmmm. Us Windows platform users tend to be a little reticent to reveal that we're using it, as it's all too easy to point at Windows and identify that as the issue.
We will certainly test the survey on fresh linux and win installs as part of tracking down the issue.
It's just strange that it's happenned since the upgrade to 1.90 and the DB heat seems to be around 'subquestion' queries. Remember - it's SQL Server that's hogging CPU, not the PHP process. It's possible that something has gone wrong with the SQL Express setup. Alternatively, limesurvey is asking it to do silly things.

Hi Tdaplyn,

I am not saying it IS Windows. I just have seen quite a few posts with performance issues and problems that usually do not appear. In my impression most of them were either using a windows server / mssql.

I think most LS developers use a Linux/Apache/PHP/MySQL combination. I can imagine that sometimes there might slip something through for MSSQL.

Was just thinking that this could be an issue that needs to be look at.

it is always hard to track these errors but if we can narrow it down, we can try to solve it. Some testing recommendations:
- test a simple, small survey
- test if conditions might be the cause
- try to track problems down by manually removing different question types from the survey
- switch to different survey modes (question by question vs all in one)

Every feedback is welcome!

Did you resolve this performance issue? We are currently running v1.90+ Build 9642 and each page loads up very slow from the Administration page as well as the surveys. We're running this on Windows Server 2003 and MySQL.

Any recommendations?

Can you test the recommendations I made above so we can try to track down the error?

Yes, I've tried what you suggested but it's not specific to any one survey but the issue is with the site as a whole. I've just tried updating PHP and the performance issue persists. I'm thinking about bringing up another server with Windows 2008 R2 and see if that helps any.

Also, I just learned that FastCGI was enabled on this server so that may be the culprit.

Thanks!

MS software sometimes seems to cause such problems. Using Apache and MySQl might be an alternative solution.

I resolved this.

When upgrading to 1.90 there were added configuration changes that needed to be updated in config.php. After adding the new configuration and restarting IIS the performance is back to normal.

So Windows wasn't an issue.

Thanks for everyone's advice/suggestions.

Johnny