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.\" -*- mode: troff; coding: utf-8 -*-
.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43)
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.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
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.ie \n(.g .ds Aq \(aq
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.\"
.\" If the F register is >0, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
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.\" ========================================================================
.\"
.IX Title "PERLDTRACE 1"
.TH PERLDTRACE 1 2024-05-30 "perl v5.38.2" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
perldtrace \- Perl's support for DTrace
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 2
\& # dtrace \-Zn \*(Aqperl::sub\-entry, perl::sub\-return { trace(copyinstr(arg0)) }\*(Aq
\& dtrace: description \*(Aqperl::sub\-entry, perl::sub\-return \*(Aq matched 10 probes
\&
\& # perl \-E \*(Aqsub outer { inner(@_) } sub inner { say shift } outer("hello")\*(Aq
\& 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
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
DTrace is a framework for comprehensive system\- and application-level
tracing. Perl is a DTrace \fIprovider\fR, meaning it exposes several
\&\fIprobes\fR 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.
.PP
Perl must be compiled with the \f(CW\*(C`\-Dusedtrace\*(C'\fR 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 \fI/usr/bin/perl\fR with DTrace support enabled.
.SH HISTORY
.IX Header "HISTORY"
.IP 5.10.1 4
.IX Item "5.10.1"
Perl's initial DTrace support was added, providing \f(CW\*(C`sub\-entry\*(C'\fR and
\&\f(CW\*(C`sub\-return\*(C'\fR probes.
.IP 5.14.0 4
.IX Item "5.14.0"
The \f(CW\*(C`sub\-entry\*(C'\fR and \f(CW\*(C`sub\-return\*(C'\fR probes gain a fourth argument: the
package name of the function.
.IP 5.16.0 4
.IX Item "5.16.0"
The \f(CW\*(C`phase\-change\*(C'\fR probe was added.
.IP 5.18.0 4
.IX Item "5.18.0"
The \f(CW\*(C`op\-entry\*(C'\fR, \f(CW\*(C`loading\-file\*(C'\fR, and \f(CW\*(C`loaded\-file\*(C'\fR probes were added.
.SH PROBES
.IX Header "PROBES"
.IP "sub\-entry(SUBNAME, FILE, LINE, PACKAGE)" 4
.IX 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
\&\fIcaller\fR from a DTrace action.
.Sp
.Vb 4
\& :*perl*::sub\-entry {
\& printf("%s::%s entered at %s line %d\en",
\& copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);
\& }
.Ve
.IP "sub\-return(SUBNAME, FILE, LINE, PACKAGE)" 4
.IX 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 \fIcaller\fR
from a DTrace action.
.Sp
.Vb 4
\& :*perl*::sub\-return {
\& printf("%s::%s returned at %s line %d\en",
\& copyinstr(arg3), copyinstr(arg0), copyinstr(arg1), arg2);
\& }
.Ve
.IP "phase\-change(NEWPHASE, OLDPHASE)" 4
.IX Item "phase-change(NEWPHASE, OLDPHASE)"
Traces changes to Perl's interpreter state. You can internalize this
as tracing changes to Perl's \f(CW\*(C`${^GLOBAL_PHASE}\*(C'\fR variable, especially
since the values for \f(CW\*(C`NEWPHASE\*(C'\fR and \f(CW\*(C`OLDPHASE\*(C'\fR are the strings that
\&\f(CW\*(C`${^GLOBAL_PHASE}\*(C'\fR reports.
.Sp
.Vb 4
\& :*perl*::phase\-change {
\& printf("Phase changed from %s to %s\en",
\& copyinstr(arg1), copyinstr(arg0));
\& }
.Ve
.IP op\-entry(OPNAME) 4
.IX 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 \fIafter\fR the debugger hooks (but
still before the opcode itself is executed).
.Sp
.Vb 3
\& :*perl*::op\-entry {
\& printf("About to execute opcode %s\en", copyinstr(arg0));
\& }
.Ve
.IP loading\-file(FILENAME) 4
.IX Item "loading-file(FILENAME)"
Fires when Perl is about to load an individual file, whether from
\&\f(CW\*(C`use\*(C'\fR, \f(CW\*(C`require\*(C'\fR, or \f(CW\*(C`do\*(C'\fR. This probe fires before the file is
read from disk. The filename argument is converted to local filesystem
paths instead of providing \f(CW\*(C`Module::Name\*(C'\fR\-style names.
.Sp
.Vb 3
\& :*perl*:loading\-file {
\& printf("About to load %s\en", copyinstr(arg0));
\& }
.Ve
.IP loaded\-file(FILENAME) 4
.IX Item "loaded-file(FILENAME)"
Fires when Perl has successfully loaded an individual file, whether
from \f(CW\*(C`use\*(C'\fR, \f(CW\*(C`require\*(C'\fR, or \f(CW\*(C`do\*(C'\fR. 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
\&\f(CW\*(C`Module::Name\*(C'\fR\-style names.
.Sp
.Vb 3
\& :*perl*:loaded\-file {
\& printf("Successfully loaded %s\en", copyinstr(arg0));
\& }
.Ve
.SH EXAMPLES
.IX Header "EXAMPLES"
.IP "Most frequently called functions" 4
.IX Item "Most frequently called functions"
.Vb 1
\& # dtrace \-qZn \*(Aqsub\-entry { @[strjoin(strjoin(copyinstr(arg3),"::"),copyinstr(arg0))] = count() } END {trunc(@, 10)}\*(Aq
\&
\& 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
.Ve
.IP "Trace function calls" 4
.IX Item "Trace function calls"
.Vb 1
\& # dtrace \-qFZn \*(Aqsub\-entry, sub\-return { trace(copyinstr(arg0)) }\*(Aq
\&
\& 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
.Ve
.IP "Function calls during interpreter cleanup" 4
.IX Item "Function calls during interpreter cleanup"
.Vb 1
\& # dtrace \-Zn \*(Aqphase\-change /copyinstr(arg0) == "END"/ { self\->ending = 1 } sub\-entry /self\->ending/ { trace(copyinstr(arg0)) }\*(Aq
\&
\& 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
.Ve
.IP "System calls at compile time" 4
.IX Item "System calls at compile time"
.Vb 1
\& # dtrace \-qZn \*(Aqphase\-change /copyinstr(arg0) == "START"/ { self\->interesting = 1 } phase\-change /copyinstr(arg0) == "RUN"/ { self\->interesting = 0 } syscall::: /self\->interesting/ { @[probefunc] = count() } END { trunc(@, 3) }\*(Aq
\&
\& lseek 310
\& read 374
\& stat64 1056
.Ve
.IP "Perl functions that execute the most opcodes" 4
.IX Item "Perl functions that execute the most opcodes"
.Vb 1
\& # dtrace \-qZn \*(Aqsub\-entry { self\->fqn = strjoin(copyinstr(arg3), strjoin("::", copyinstr(arg0))) } op\-entry /self\->fqn != ""/ { @[self\->fqn] = count() } END { trunc(@, 3) }\*(Aq
\&
\& warnings::unimport 4589
\& Exporter::Heavy::_rebuild_cache 5039
\& Exporter::import 14578
.Ve
.SH REFERENCES
.IX Header "REFERENCES"
.IP "DTrace Dynamic Tracing Guide" 4
.IX Item "DTrace Dynamic Tracing Guide"
<http://dtrace.org/guide/preface.html>
.IP "DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD" 4
.IX Item "DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD"
<https://www.amazon.com/DTrace\-Dynamic\-Tracing\-Solaris\-FreeBSD/dp/0132091518/>
.SH "SEE ALSO"
.IX Header "SEE ALSO"
.IP Devel::DTrace::Provider 4
.IX Item "Devel::DTrace::Provider"
This CPAN module lets you create application-level DTrace probes written in
Perl.
.SH AUTHORS
.IX Header "AUTHORS"
Shawn M Moore \f(CW\*(C`sartak@gmail.com\*(C'\fR
|
