>>>>> "Rafael" == Rafael Garcia-Suarez <[EMAIL PROTECTED]> writes:
Rafael> Alexander Kolbasov wrote:
>> Solaris (*) has a dynamic instrumentation tool called DTrace. It allows
to
>> *dynamically* instrument any running application and get useful
information
>> about its behavior with zero (or almost zero) impact on the application
when it
>> is not instrumented.
>>
>> This works fine with normal applications, but not so good with
interpteded
>> languages since C function names and data types have little to do with
the
>> structure of the interpreted language. I am playing with the idea of
adding some
>> hooks to Perl5 that will allow DTrace to be used for Perl programs (**).
As an
Rafael> Maybe are you aware of
Rafael> http://blogs.sun.com/roller/page/alanbur?entry=dtrace_and_perl
already ?
Thanks for the pointer! It seems that Alan already made a pretty good progress
on adding probes for subroutines. I am still curious whether it is possible to
use DTrace to be able to trace based on Perl line numbers. IMO this will add a
*tremendous* value.
>> initial experiment I changed Perl_runops_standard() function a bit and
was able
>> to use DTrace to trace start and end of each Perl OP evaluation. This is
not
Rafael> You can also plug in your own runloop at compile time. See for
example
Rafael> my module Runops::Switch on CPAN.
Cool! I'll take a look at it. Does it have the knowledge of the current file and
line numbers and when execution switches from line X to Y?
Rafael> The line number isn't stored in all ops, but only in COPs. You then
get
Rafael> it with the CopLINE macro, see cop.h.
How do I know whether I am dealing with COP? Also, looking at cop.h it seems
that getting file/lines with USE_ITHREADS is pretty cheap but otherwise can be
quite expensive. Is it a way to get file/line number information from the op
tree (may be not from every op) cheaply? For example, would it be reasonable
(performance-wise) to get line/file information once per Perl_runops_standard()
entry? Would it make any sense to do so?
In my prototype I changed Perl_runops_standard() to
int
Perl_runops_standard(pTHX)
{
OP* (CPERLscope(*op_addr))(pTHX) = PL_op->op_ppaddr;
/*
* Would be really cool to insert here something like
*
* DTRACE_PROBE2(perl__line, file_name, line_number);
*
*/
do {
DTRACE_PROBE1(perl, call__entry, op_addr);
PL_op = CALL_FPTR(op_addr)(aTHX);
DTRACE_PROBE1(perl, call__return, op_addr);
if (!PL_op)
break;
op_addr = PL_op->op_ppaddr;
PERL_ASYNC_CHECK();
} while (1);
TAINT_NOT;
return 0;
}
P.S. Please bear in mind that I am *really* ignorant in Perl internals.
- Alexander Kolbasov
