Edit: /usr/share/perl5/pod/perldtrace.pod (7959B)
=head1 NAME
perldtrace - Perl's support for DTrace
=head1 SYNOPSIS
# dtrace -Zn 'perl::sub-entry, perl::sub-return { trace(copyinstr(arg0)) }'
dtrace: description 'perl::sub-entry, perl::sub-return ' matched 10 probes
# perl -E 'sub outer { inner(@_) } sub inner { say shift } outer("hello")'
hello
(dtrace output)
CPU ID FUNCTION:NAME
0 75915 Perl_pp_entersub:sub-entry BEGIN
0 75915 Perl_pp_entersub:sub-entry import
0 75922 Perl_pp_leavesub:sub-return import
0 75922 Perl_pp_leavesub:sub-return BEGIN
0 75915 Perl_pp_entersub:sub-entry outer
0 75915 Perl_pp_entersub:sub-entry inner
0 75922 Perl_pp_leavesub:sub-return inner
0 75922 Perl_pp_leavesub:sub-return outer
=head1 DESCRIPTION
DTrace is a framework for comprehensive system- and application-level
tracing. Perl is a DTrace I
, meaning it exposes several
I for instrumentation. You can use these in conjunction
with kernel-level probes, as well as probes from other providers
such as MySQL, in order to diagnose software defects, or even just
your application's bottlenecks.
Perl must be compiled with the C<-Dusedtrace> option in order to
make use of the provided probes. While DTrace aims to have no
overhead when its instrumentation is not active, Perl's support
itself cannot uphold that guarantee, so it is built without DTrace
probes under most systems. One notable exception is that Mac OS X
ships a F with DTrace support enabled.
=head1 HISTORY
=over 4
=item 5.10.1
Perl's initial DTrace support was added, providing C and
C probes.
=item 5.14.0
The C and C probes gain a fourth argument: the
package name of the function.
=item 5.16.0
The C probe was added.
=item 5.18.0
The C, C, and C probes were added.
=back
=head1 PROBES
=over 4
=item sub-entry(SUBNAME, FILE, LINE, PACKAGE)
Traces the entry of any subroutine. Note that all of the variables
refer to the subroutine that is being invoked; there is currently
no way to get ahold of any information about the subroutine's
I from a DTrace action.
:*perl*::sub-entry {
printf("%s::%s entered at %s line %d\n",
copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);
}
=item sub-return(SUBNAME, FILE, LINE, PACKAGE)
Traces the exit of any subroutine. Note that all of the variables
refer to the subroutine that is returning; there is currently no
way to get ahold of any information about the subroutine's I
from a DTrace action.
:*perl*::sub-return {
printf("%s::%s returned at %s line %d\n",
copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);
}
=item phase-change(NEWPHASE, OLDPHASE)
Traces changes to Perl's interpreter state. You can internalize this
as tracing changes to Perl's C<${^GLOBAL_PHASE}> variable, especially
since the values for C and C are the strings that
C<${^GLOBAL_PHASE}> reports.
:*perl*::phase-change {
printf("Phase changed from %s to %s\n",
copyinstr(arg1), copyinstr(arg0));
}
=item op-entry(OPNAME)
Traces the execution of each opcode in the Perl runloop. This probe
is fired before the opcode is executed. When the Perl debugger is
enabled, the DTrace probe is fired I the debugger hooks (but
still before the opcode itself is executed).
:*perl*::op-entry {
printf("About to execute opcode %s\n", copyinstr(arg0));
}
=item loading-file(FILENAME)
Fires when Perl is about to load an individual file, whether from
C