[LRUG] Ruby on Rails - performance tuning advice

[Frederick Cheung]

What instrumentation do you have in place to tell you what is slow? That's always the first step, so that you know whether you should be tuning/rewriting db queries, reimplementing an algorithm etc. We use newrelic in production to have an overall idea of what is going on, and there's ruby-prof for detailed profiling (the only danger there is because ruby-prof makes your ruby code run slower, it can make it seem that external services, db queries etc. are less of a problem than they really are)
 

In the past I've seen performance problems fixed by

- database changes: removing duplicate database queries, adding the right index to a query, working out that the db structure is fundamentally not suited to what we want to store (so either structure your data differently or pick a different data store. In my case we were trying to do with ActiveRecord what was better done with elasticsearch)
- rewriting ruby hotspots in C (not necessarily by you - perhaps the problem you are trying to solve has a fast implementation you can use)
- caching (i meant this in a very vague sense, so not just fragment caching etc. but in memory caching of intermediate results of calculations for example)
- rewriting algorithms to suck less

But all of those are step 2. Step 1 is to find your bottlenecks (admittedly sometimes it's more a death by a thousand cuts sort of thing)

Fred




On 26 March 2014 at 14:02:35, Nicholas Martin (nic_i_like_to_ at hotmail.com) wrote:
> Hi,
> We are currently working to improve performance of our Rails application.
> There is a lot of information out there in the Rails Guides and various blog posts.
> However, the challenge is finding what things will give us the best results. For example,  
> in the work we have done so far, code changes to aggregate data have helped a lot, caching  
> less so.
> Any advice, based on experience would be most appreciated. Any form would be of interest,  
> from a short reply, to a chat over a coffee or even potentially a day or so of consultancy.  
> Cheers,Nic.
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