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 outerDTrace is a framework for comprehensive system- and application-level tracing. Perl is a DTraceprovider, meaning it exposes severalprobes 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.
Perl's initial DTrace support was added, providingsub-entry andsub-return probes.
Thesub-entry andsub-return probes gain a fourth argument: the package name of the function.
Thephase-change probe was added.
Theop-entry,loading-file, andloaded-file probes were added.
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'scaller from a DTrace action.
:*perl*::sub-entry { printf("%s::%s entered at %s line %d\n", copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);}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'scaller from a DTrace action.
:*perl*::sub-return { printf("%s::%s returned at %s line %d\n", copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);}Traces changes to Perl's interpreter state. You can internalize this as tracing changes to Perl's${^GLOBAL_PHASE} variable, especially since the values forNEWPHASE andOLDPHASE are the strings that${^GLOBAL_PHASE} reports.
:*perl*::phase-change { printf("Phase changed from %s to %s\n", copyinstr(arg1), copyinstr(arg0));}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 firedafter the debugger hooks (but still before the opcode itself is executed).
:*perl*::op-entry { printf("About to execute opcode %s\n", copyinstr(arg0));}Fires when Perl is about to load an individual file, whether fromuse,require, ordo. This probe fires before the file is read from disk. The filename argument is converted to local filesystem paths instead of providingModule::Name-style names.
:*perl*:loading-file { printf("About to load %s\n", copyinstr(arg0));}Fires when Perl has successfully loaded an individual file, whether fromuse,require, ordo. 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 providingModule::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 400Try::Tiny::catch 411Try::Tiny::try 411Class::MOP::Instance::inline_slot_access 451Class::MOP::Class::Immutable::Trait:::around 472Class::MOP::Mixin::AttributeCore::has_initializer 496Class::MOP::Method::Wrapped::__ANON__ 544Class::MOP::Package::_package_stash 737Class::MOP::Class::initialize 1128Class::MOP::get_metaclass_by_name 1204# dtrace -qFZn 'sub-entry, sub-return { trace(copyinstr(arg0)) }'0 -> Perl_pp_entersub BEGIN0 <- Perl_pp_leavesub BEGIN0 -> Perl_pp_entersub BEGIN0 -> Perl_pp_entersub import0 <- Perl_pp_leavesub import0 <- Perl_pp_leavesub BEGIN0 -> Perl_pp_entersub BEGIN0 -> Perl_pp_entersub dress0 <- Perl_pp_leavesub dress0 -> Perl_pp_entersub dirty0 <- Perl_pp_leavesub dirty0 -> Perl_pp_entersub whiten0 <- Perl_pp_leavesub whiten0 <- 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 310read 374stat64 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 4589Exporter::Heavy::_rebuild_cache 5039Exporter::import 14578http://www.amazon.com/DTrace-Dynamic-Tracing-Solaris-FreeBSD/dp/0132091518/
This CPAN module lets you create application-level DTrace probes written in Perl.
Shawn M Mooresartak@gmail.com
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