Troubleshooting web performance

Been working on a tricky problem which shows how you have to be methodical to try and find the problem

Our helpdesk database was running very slow

so i upgraded the instance ram – this made loading pages faster but seem to make any writes to the mysql db slower!

Now this is a lightly loaded server so should be lightening fast

I looked at the apache logs – nothing obvious but a couple of errors

I upgraded the system to the latest version – this enabled me to spot the first problem

Schema updates had not been applied – this is fairly painless – take a back up and run

rt-setup-database-4 –action upgrade

This boosted the load times but still did little for the saving

after trailing round the RT forums it occurred to me that there must be a simple solution

I disabled various ad-ons – no real change

Then i realised the problem was SENDING emails – the way its setup it waits for sendmail to send the message BEFORE loading the next webpage

So why was it taking so long to load?

In the end it was our old friend DNS – removed the dead dns server  from resolv.conf (which was obviously timing out) and much much faster

With hindsight – it was taking a little while to ssh to the server – this was caused by the same problem, but wasn’t really  a problem.

So next time i get slow ssh’s into a server i will remember – check your dns setup!

I could change the configuration to not wait for sendmail to finish  – but lets see how it goes…





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