bhb/rack-perftools_profiler — Issue #15: Unable to get useful profiling data
Author: arsduo
Created: 2012-01-30 08:19:27+00:00
State: open

Hi,

Apologies for opening an issue on what may be an implementation question, but I'm unable to get useful profiling data, and the Googling doesn't turn up any useful information. Regardless of how high I set the sampling rate (currently 300) or how many times I rerun the operation using the times parameter (10, 20, higher tends to not send back a response to the browser) the generated PDF always says there's just one sample, and unsurprisingly (given only one sample) usually doesn't have any useful information on what calls were made. It's mostly just the chain of Rack middleware, ending in something like IO#read or Time#new, which takes up 100% of the one sample. Even when it shows a number of code paths being executed, the sample size never increases, which makes it hard to figure out where to optimize.

Have seen anything like this had any experience with this? Is it just that the method is too fast (though in that case, should times=20 still produce data)? Unfortunately the project isn't public so I can't link to the code, but I'd be happy to provide whatever other information I can. The app is running locally in production mode, and the middleware is set up simply as config.middleware.use ::Rack::PerftoolsProfiler, { :default_printer => 'pdf', :bundler => true}, my call parameters are ?profile=true×=20.

Any help would be most appreciated.

Thanks!

Alex