Charles Oliver Nutter wrote:
Now that we've gotten JRuby's own startup time down pretty low, I
thought I'd start examining the startup time of nontrivial real-world
apps. The biggest one of those, obviously, is Rails.
Rails 2.1 with Mongrel (in development mode) starts up in about 12
seconds on my machine, using soylatte Java 6, on OS X 10.5, a Core Duo
2.16GHz processor, and 2GB of memory. C Ruby starts up in about 8
seconds, so we're actually not so far off the mark here.
I added a ParserStats MBean to explore whether parse time might be a
problem. Of course without knowing MRI's parse time, it's hard to know
if this is good or bad, but here's the stats I gathered:
* A total of 5.512MB of source are parsed during Rails startup
* Total parse time spent was around 3.08s
* There were 503 parses due to file loads
* There were 1943 parses due to evals
One more metric on parsing...
I pulled out the long benchmark from bench_eval and ran it with --manage
to compare the total time versus the parse time. The two runs of the
eval benchmark were 18.2s and 17.9s for a total of about 36.1s.
According to the ParserStats MBean, total parse time for the whole run
was 32.66s. So I think it's at least safe to say that almost all the
overhead of eval is parsing/ast construction.
- Charlie
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