Issue #2565 has been updated by Yui NARUSE.


Mark's concern, why Ruby doesn't include DTrace support, is reasonable, I explain why.
It is because tracing is so important that we can't implement it without careful design.
But we know such too careful way annoys you.
So we are considering that 2.0 (not 1.9.3) includes experimental tracing support.
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Feature #2565: adding hooks for better tracing
http://redmine.ruby-lang.org/issues/2565

Author: Yuki Sonoda
Status: Assigned
Priority: Low
Assignee: Yuki Sonoda
Category: core
Target version: 1.9.x


=begin
 Hi,
 
 I made a commit that embeded dtrace probes into Ruby so that you can
 profile a Ruby application at runtime. (r26235)
 
 Adding probes had been approved by a Ruby developer's meeting,
 however, the commit was little larger than what other committers
 expected. I got some objection for the commit. [ruby-dev:39954]
 In the end, I decided to temporarily revert the commit. (r26243)
 
 I discussed how we should support dynamic runtime tracing, with ko1,
 mame, naruse, unak and shyouhei. The problems of the commit were:
 * the probes duplicated with the event_hook framework
 (rb_add_event_hook, Kernel#set_trace_func)
 * Design of the probes were not verified enough.
   * more trial and error are necessary, to make it clear what is
 necessary to trace a Ruby application.
 
 I accepted ko1's suggestion:
 * reverting the commit
 * adding some hooks for rb_add_event_hook().
 * implementing probes for dynamic runtime tracing on the event_hook framework.
   * these probes can be implemented as a gem
   * I will aget a chance for trial and error.
   * The probes possibly will be merged into Ruby itself after enough
 designed and getting enough use cases.
 
 Here is a patch to add the hooks I and ko1 talked about. (attached)
 And here is an extension library that provides prove points to dtrace,
 on top of the hooks. (http://github.com/yugui/vm_probes )
 
 What do you think?  Can I commit the patch I attached?
 
 Thank you,
 -- Yuki Sonoda (Yugui)
 
 Attachment: adding-hooks.patch
=end



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