perl, DTrace and you

This is an overview of the DTrace functionality in perl 5.10.1 and later. It's suitable for someone familiar with perl but not very familiar with DTrace.

https://github.com/mrallen1/perl-Tombala

Transcript

1. DTrace, Perl and you! ! ! Mark Allen! mrallen1@yahoo.com! @bytemeorg! http://byte-me.org! https://github.com/mrallen1! https://metacpan.org/author/MALLEN!
2. DTrace Basics What is DTrace?!
3. DTrace Basics Dynamic Tracing!
4. DTrace Basics Dude! Srsly?!! Dynamic versus what?!!
5. DTrace Basics Dynamic versus! warn Dumper $object if $debug; print "got here!\n"; my $start = time(); do_stuff(); my $elapsed = time() - $start;
6. DTrace Basics "Observability technology"1! 1  DTrace:  Dynamic  Tracing  in  Oracle  Solaris,  Pren(ce  Hall,  2nd  ed,  2012.  
7. DTrace Basics In a DTrace enabled OS, you get full scope visibility!
8. DTrace Basics Applica(on   Libraries   System   Calls   Kernel  
9. DTrace Basics It's turtles all the way down...! h?p://flic.kr/p/aQDPrZ  
10. DTrace Basics It's like X-Ray vision into your application and operating system.! ! (And it's fun!)! (And it's neckbeardy!1one)!
11. DTrace Basics Examples:! •  Trace socket accepts and debug your web application's "real" code execution pathway! •  Profile why NFS gets super busy at 0430 and a directory tree traversal takes 2 hours instead of 2 minutes.!
12. DTrace Basics DTrace enabled OSes:! •  Solaris 10+! •  OpenSolarisIllumos! •  SmartOS (Joyent)! •  OmniOS (OmniTI)! •  FreeBSD! •  Mac OS X!
13. DTrace Basics What about Linux?!
14. DTrace Basics You're looking for the talk! "SystemTap, perl and you"! ! Try down the hall, on the left.! ! ! (Sorry)  
15. DTrace Basics DTrace Terms!
16. DTrace Basics Provider! ! Manages probes in a subsystem!
17. DTrace Basics Provider! ! In our case, this is the perl binary itself. ! ! (More on this soon)!
18. DTrace Basics Probes! ! DTrace ! instrumentation or! "observables"!
19. DTrace Basics Consumer! ! A user-mode program! that calls into DTrace!
20. D Language Basics D Language Basics!
21. D Language Basics D Language Overview! •  awk-like! •  Define a probe, optional predicate and optional actions in a braced clause! •  Supports BEGIN and END blocks! •  Local variables (this->foo = 42)! •  Aggregate/associative variables (prefixed with @)! •  One liner support in the form! dtrace -n 'probe /predicate/ {action}'
22. D Language Basics $ cat dtrace-example.d #!/usr/sbin/dtrace -s probe /predicate/ { actions }
23. D Language Basics Example 1!
24. D Language Basics REAL Example 1!
25. D Language Basics $ cat subentry.d #!/usr/sbin/dtrace -qFZs sub-entry, sub-return { /* arg0 is subroutine name */ trace(copyinstr(arg0)) }
26. D Language Basics $ cat subentry.d #!/usr/sbin/dtrace -qFZs sub-entry, sub-return { /* arg0 is subroutine name */ trace(copyinstr(arg0)) }
27. D Language Basics $ cat subentry.d #!/usr/sbin/dtrace -qFZs sub-entry, sub-return { /* arg0 is subroutine name */ trace(copyinstr(arg0)) }
28. D Language Basics REAL Example 2!
29. D Language Basics $ cat subcount.d #!/usr/sbin/dtrace -qZs sub-entry { /* Count sub entries by package and sub name * arg3 = package name (Foo::Bar) * arg0 = subroutine name (do_something) */ @[strjoin(strjoin(copyinstr(arg3),"::"),copyinstr(arg0))] = count() } END { /* Give me top 10 highest counts; throw away rest */ trunc(@, 10) }
30. D Language Basics $ cat subcount.d #!/usr/sbin/dtrace -qZs sub-entry { /* Count sub entries by package and sub name * arg3 = package name (Foo::Bar) * arg0 = subroutine name (do_something) */ @[strjoin(strjoin(copyinstr(arg3),"::"),copyinstr(arg0))] = count() } END { /* Give me top 10 highest counts; throw away rest */ trunc(@, 10) }
31. D Language Basics $ cat subcount.d #!/usr/sbin/dtrace -qZs sub-entry { /* Count sub entries by package and sub name * arg3 = package name (Foo::Bar) * arg0 = subroutine name (do_something) */ @[strjoin(strjoin(copyinstr(arg3),"::"),copyinstr(arg0))] = count() } END { /* Give me top 10 highest counts; throw away rest */ trunc(@, 10) }
32. D Language Basics $ cat subcount.d #!/usr/sbin/dtrace -qZs sub-entry { /* Count sub entries by package and sub name * arg3 = package name (Foo::Bar) * arg0 = subroutine name (do_something) */ @[strjoin(strjoin(copyinstr(arg3),"::"),copyinstr(arg0))] = count() } END { /* Give me top 10 highest counts; throw away rest */ trunc(@, 10) }
33. D Language Basics subcount.d  for  Pod::Perldoc  3.20  
34. D Language Basics Common aggregation functions! •  avg! •  count! •  lquantize (linear)! •  quantize (log - power of 2)! •  sum! •  min! •  max!
35. DTrace and Perl DTrace and Perl!
36. DTrace and Perl Mac OS X vendor perl ships with DTrace.!
37. DTrace and Perl Build your own with perlbrew perlbrew install \ perl-5.18.0 \ --as 5.18-dtrace \ -Dusedtrace
38. DTrace and Perl Build your own with perlbrew perlbrew install \ perl-5.18.0 \ --as 5.18-dtrace \ -Dusedtrace
39. DTrace and Perl DTrace support by Perl release! Perl release! DTrace probes! 5.10.1! sub-entry, sub-return! 5.14.x! sub-entry and return get package name as an argument! 5.16.x! phase-change! 5.18.0! op-entry, loading-file, loaded- file!
40. DTrace and Perl sub-entry! sub-return! (SUBNAME, FILE, LINE, PACKAGE)
41. DTrace and Perl phase-change! (NEWPHASE, OLDPHASE)
42. DTrace and Perl op-entry! (OPNAME) Fires before op executed. If the debugger is active, fires after debug hooks but still before the op is executed.!
43. DTrace and Perl loading-file (fires before load)! loaded-file (fires after load)! ! (FILENAME) The filename is a path! (e.g., Foo/Bar not Foo::Bar)!
44. DTrace and Perl Make your own DTrace probes in Perl by using ! ! Devel::DTrace::Provider! !
45. DTrace and Perl Sample use cases:! •  Trace when you hit your DBI handle.! •  Trace when you connect to a socket.! •  Lots of other possibilities.! !
46. Resources DTrace resources:! •  perldoc dtrace •  http://dtracehol.com/#Intro •  http://dtrace.org/guide/preface.html •  http://dtracebook.com/index.php/ Languages#Perl •  http://www.amazon.com/dp/0132091518
47. Thanks! Thank you!!