[ruby-core:46870] Re: [ruby-trunk - Feature #2565] adding hooks for better tracing

On Sun, Jul 29, 2012 at 12:02:27PM +0900, SASADA Koichi wrote:
> Sorry for late response.
> 
> (2012/07/19 3:52), tenderlovemaking (Aaron Patterson) wrote:
> >   https://bugs.ruby-lang.org/projects/ruby/wiki/DTraceProbes
> 
> my comments:
> 
> > ruby:::function-entry(classname, methodname, filename, lineno);
> > ruby:::function-return(classname, methodname, filename, lineno);
> 
> set_trace_func spearates "call" and "c-call" (and return).
> No need to separate on dtrace?

I don't think we need to separate these.  Information like that hasn't
been useful to me when debugging or profiling my ruby programs.

> > ruby:::require-entry(requiredfile, filename, lineno);
> > ruby:::require-return(filename);
> > ruby:::load-entry(loadedfile, filename, lineno);
> > ruby:::load-return(filename);
> 
> Do we need `require' and `load' both needed? (It depends on usecase)

I'm not sure we need both.  What I *want* is a way to know when Ruby
starts and finishes loading a file.

> What happen on exception?

The `raise` probe is fired.

> (There is a same question on `function-entry')
> 
> > ruby:::object-create-start(classname, filename, lineno);
> > ruby:::object-create-done(classname, filename, lineno);
> 
> (1) How to detect object creation and finish of creation?

rb_obj_alloc has probes.  It wraps object allocation.

> (2) I can't accept your patch on insns.def on string and array.

Why?  You want specific string / array / hash probes (like below)?

> IIRC, you suggest that String creation trace and Array creation trace
> and so on.  I write examples:
> 
>   ruby:::string-create(filename, lineno, size)
>   ruby:::array-create(filename, lineno, size)
>   ruby:::hash-create(filename, lineno, size)
>   ruby:::object-create(filename, lineno, classname)
> 
>   size is string or array size.
>   classname is a classname of object.

These seem good.  I can implement them.

> I'm not sure we need string-modified (size) are needed.

I tried doing this once, but it seemed like the patch was too large.  I
wanted to start small. :)

> ruby:::object-collected(object_id) will be help.  To use it correctly,
> object-create needs to pass object_id.  But it will be complicated.
> 
> > ruby:::gc-begin();
> > ruby:::gc-end();
> 
> How to define GC begin and end?

Nari-san already has defined GC begin and end for GC::Profiler.  See the
GC_PROF_TIMER_START and GC_PROF_TIMER_STOP macros:

  https://github.com/ruby/ruby/blob/trunk/gc.c#L180
  https://github.com/ruby/ruby/blob/trunk/gc.c#L199

My patch just adds the DTrace probes to his existing macros.

> > ruby:::gc-sweep-begin();
> > ruby:::gc-sweep-end();
> 
> How to define GC sweep begin and end?

Same here.  Nari-san has already defined GC_PROF_SWEEP_TIMER_START and
GC_PROF_SWEEP_TIMER_STOP for GC::Profiler.  My patch just adds probes by
his existing macros.

> > ruby:::line(filename, lineno);
> 
> Your patch depends on the `trace' instruction.  I plan to remove `trace'
> instruction on default (if I can implement it).  It will conflicts with
> your proposed patch.
> Or I shouldn't make such optimizations?

I think we should remove this.  I added it for backwards compatibility
with Joyant's DTrace probes, but I never use this.  Besides backwards
compatibility, I don't think it's a useful probe.

-- 
Aaron Patterson
http://tenderlovemaking.com/