| perldtrace - Perl's support for DTrace |
perldtrace - Perl's support for DTrace
# 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
DTrace is a framework for comprehensive system- and application-level tracing. Perl is a DTrace provider, meaning it exposes several probes 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 -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 /usr/bin/perl with DTrace support enabled.
sub-entry and
sub-return probes.
sub-entry and sub-return probes gain a fourth argument: the
package name of the function.
phase-change probe was added.
op-entry, loading-file, and loaded-file probes were added.
:*perl*::sub-entry {
printf("%s::%s entered at %s line %d\n",
copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);
}
:*perl*::sub-return {
printf("%s::%s returned at %s line %d\n",
copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);
}
${^GLOBAL_PHASE} variable, especially
since the values for NEWPHASE and OLDPHASE are the strings that
${^GLOBAL_PHASE} reports.
:*perl*::phase-change {
printf("Phase changed from %s to %s\n",
copyinstr(arg1), copyinstr(arg0));
}
:*perl*::op-entry {
printf("About to execute opcode %s\n", copyinstr(arg0));
}
use, require, or do. This probe fires before the file is
read from disk. The filename argument is converted to local filesystem
paths instead of providing Module::Name-style names.
:*perl*:loading-file {
printf("About to load %s\n", copyinstr(arg0));
}
use, require, or do. This probe fires after the file
is read from disk and its contents evaluated. The filename argument
is converted to local filesystem paths instead of providing
Module::Name-style names.
:*perl*:loaded-file {
printf("Successfully loaded %s\n", copyinstr(arg0));
}
# dtrace -qZn 'sub-entry { @[strjoin(strjoin(copyinstr(arg3),"::"),copyinstr(arg0))] = count() } END {trunc(@, 10)}'
Class::MOP::Attribute::slots 400 Try::Tiny::catch 411 Try::Tiny::try 411 Class::MOP::Instance::inline_slot_access 451 Class::MOP::Class::Immutable::Trait:::around 472 Class::MOP::Mixin::AttributeCore::has_initializer 496 Class::MOP::Method::Wrapped::__ANON__ 544 Class::MOP::Package::_package_stash 737 Class::MOP::Class::initialize 1128 Class::MOP::get_metaclass_by_name 1204
# dtrace -qFZn 'sub-entry, sub-return { trace(copyinstr(arg0)) }'
0 -> Perl_pp_entersub BEGIN 0 <- Perl_pp_leavesub BEGIN 0 -> Perl_pp_entersub BEGIN 0 -> Perl_pp_entersub import 0 <- Perl_pp_leavesub import 0 <- Perl_pp_leavesub BEGIN 0 -> Perl_pp_entersub BEGIN 0 -> Perl_pp_entersub dress 0 <- Perl_pp_leavesub dress 0 -> Perl_pp_entersub dirty 0 <- Perl_pp_leavesub dirty 0 -> Perl_pp_entersub whiten 0 <- Perl_pp_leavesub whiten 0 <- Perl_dounwind BEGIN
# dtrace -Zn 'phase-change /copyinstr(arg0) == "END"/ { self->ending = 1 } sub-entry /self->ending/ { trace(copyinstr(arg0)) }'
CPU ID FUNCTION:NAME 1 77214 Perl_pp_entersub:sub-entry END 1 77214 Perl_pp_entersub:sub-entry END 1 77214 Perl_pp_entersub:sub-entry cleanup 1 77214 Perl_pp_entersub:sub-entry _force_writable 1 77214 Perl_pp_entersub:sub-entry _force_writable
# dtrace -qZn 'phase-change /copyinstr(arg0) == "START"/ { self->interesting = 1 } phase-change /copyinstr(arg0) == "RUN"/ { self->interesting = 0 } syscall::: /self->interesting/ { @[probefunc] = count() } END { trunc(@, 3) }'
lseek 310 read 374 stat64 1056
# dtrace -qZn 'sub-entry { self->fqn = strjoin(copyinstr(arg3), strjoin("::", copyinstr(arg0))) } op-entry /self->fqn != ""/ { @[self->fqn] = count() } END { trunc(@, 3) }'
warnings::unimport 4589 Exporter::Heavy::_rebuild_cache 5039 Exporter::import 14578
Shawn M Moore sartak@gmail.com
| perldtrace - Perl's support for DTrace |