From: Eric Wong <normalperson@...>
Date: 2011-04-11T08:52:13+09:00
Subject: [ruby-core:35694] Re: [Ruby 1.9 - Feature #4560] [PATCH]	lib/net/protocol.rb: avoid exceptions in rbuf_fill

redmine@ruby-lang.org wrote:
> On JRuby master, I've made a change that does not generate backtraces
> for EAGAIN, to avoid the overhead of generating it for the expected
> case of read_nonblock having nothing available. But it's a bit of a
> band-aid. The overhead from even *creating* an exception can be weigh
> into a tight loop over read_nonblock when there's nothing available,
> and of course having the backtrace disabled could annoy someone if it
> leaked out (JRuby points them to a flag to turn the backtraces on).
> Not sure what's the best long-term solution.

Perhaps something similar to the kgio[1] API with IO#tryread/trywrite
(that return :wait_readable/:wait_writable Symbols) can be moved into
the core Ruby IO class (and deprecate IO#read_nonblock/write_nonblock).

> Also, the 1.9 practice of mixing in WaitReadable is really dreadful.
> It's bad enough in JRuby that it has to construct a new singleton
> class for every raised exception, but the cache effects in 1.9 are
> really painful.

Yes, I've been trying to fix that in trunk, too: [ruby-core:35672]

[1] http://bogomips.org/kgio - *nix-only, but the API is fully RDoc-ed

-- 
Eric Wong