Question

I am trying out ruby-prof and ran it against a somewhat self-contained module. The core of the module is 3 classes, with maybe 3 other helper classes being used. So there shouldn’t be a huge amount of overhead with tons of requires and incluces. Is this normal in a big(gish) app with a fair number of gems installed?

 18.06      7.67     1.99     0.00     7.66     1366  Kernel#require
  5.80      1.21     0.64     0.00     0.83    18704  Array#map
  5.73     10.21     0.63     0.00    10.09    38133  Array#each
  5.17      1.13     0.57     0.00     0.56    21796  Array#include?
  4.40      0.49     0.49     0.00     0.00   345434  Symbol#to_s
  3.78      0.42     0.42     0.00     0.00   446478  String#==

Answer 1

From ruby-prof‘s documentation:

To profile a Rails application it is
vital to run it using production like
settings (cache classes, cache view
lookups, etc.). Otherwise, Rail’s
dependency loading code will overwhelm
any time spent in the application
itself (our tests show that Rails
dependency loading causes a roughly 6x
slowdown).

Are you running this using production settings? If you aren’t using cached data and instead have to read the files/classes from disk every time, I can understand why you are seeing your system spend so much time in Kernel#require.