Dynamic Tracing of your AMP web site

1. Dynamic Tracing your AMP site Sriram Natarajan Engineer Sun Microsystems Inc

2. What is Dtrace ? Old school performance analysis Collect data as required.

3. Analyze data looking for bottlenecks, trends and correlations.

4. Speculate on remedies

5. Evaluate and repeat the process Does not replace any of the existing tools like vmstat, mpstat, prstat, sar etc..

6. Largely new functionality to ask questions.

7. How does it work ? Ability to instrument binary code on the fly

8. Zero probe effect when Dtrace is not running.

9. Does a fast trap into Dtrace probe to minimize performance impact.

10. A simple Dtrace script #!/usr/sbin/dtrace -qs syscall:::entry { @num[probefunc] = count() }

11. Dtrace format ● provider:module:function:name ● -P provider ● -m module ● -f function ● -n name ● -s script ● -p pid ● -c run command ● -l list ● -v verbose

12. How to write a Dtrace script Sample Dtrace scripts. /usr/demo/dtrace (Solaris 10/OpenSolaris) Dtracetoolkit includes task specific Dtrace scripts for OpenSolaris. /opt/DTT (OpenSolaris)

13. http://www.opensolaris.org/os/community/dtrace/dtracetoolkit/ Customize and built upon these sample scripts.

14. MySQL sample Dtrace scripts are available at http://dev.mysql.com/doc/refman/6.0/en/dba-dtrace-mysqld-ref.html

15. Dtrace for AMP stack Apache Dtrace probes are made possible by Apache Dtrace extension

16. MySQL / PHP Dtrace probes are enabled within engine

17. Fired when execution flow reaches probe location.

18. No overhead for inactive probes.

19. Provide hard to get under the hood information in a simple way.

20. Some performance hit depending on number of probes fired

21. Sample MySQL D Script #!/usr/sbin/dtrace -qs dtrace:::BEGIN { printf("%-40s %2s %-9s\n", "Query", "QC", "Time(ms)"); } mysql*:::query-start { self->query = copyinstr(arg0); self->querystart = timestamp; self->qc = 0; } mysql*:::query-cache-hit { self->qc = 1; } mysql*:::query-cache-miss { self->qc = 0; } mysql*:::query-done { printf("%-40s %-2s %-9d\n",self->query,(self->qc ? "Y" : "N"), (timestamp - self->querystart) / 1000000); }

22. Sample MySQL D Script Output select * from t1 order by i limit 10 N 1072 set global query_cache_size=262144 N 0 select * from t1 order by i limit 10 N 781 select * from t1 order by i limit 10 Y 0 select * from t1 order by i limit 30 Y 0 select * from t1 order by i limit 10 Y 0 select * from t1 order by i limit 10 Y 0

23. MySQL Dtrace probes connection-start(id, user, hostname) connection-done(status, id) command-start(id, command_id) command-end(status) query-start(query, id, db, user, host) query-done(status) query-parse-start(query) query-parse-done(status) query-cache-hit(query, row) query-cache-miss(query) query-exec-start(query, id, db, host, exec_type) query-exec-done(status) insert/update/delete-row-start(db, table, status) insert/update/delete-row-done(db, table, status) select/insert/update/multi-update-start(query, status, rows, rowsmatched, rowschanged) select/insert/update/multi-update-done(query, status, rows, rowsmatched, rowschanged)

24. Sample PHP D Script php*:::compile-file-entry /arg0 != NULL/ { self->compile_file = copyinstr(arg0); self->compile_start_time = timestamp; } php*:::compile-file-return /self->compile_file == copyinstr(arg0)/ { self->compile_elapsed = ((timestamp - self->compile_start_time) / 1000000); @compile_time[self->compile_file] = quantize(self->compile_elapsed); self->compile_file = 0; self->compile_file_translated = 0; self->compile_start_time = 0; } tick-60s { printf("\nExclusive compile elapsed times,\n"); printa(" %s, %@d\n", @compile_time); }

25. PHP Dtrace probes request-startup(request-file, request-uri, request-method) request-end(request-file, request-uri, request-method) compile-file-entry(compile-file, compile-file-translated) compile-file-return(compile-file, compile-file-translated) function-entry(function-name, request-file, lineno, classname, scope) function-end(function-name, request-file, lineno, classname, scope) execute-entry(request-file, lineno) execute-end(request-file, lineno) error(errormsg, request-file, lineno) execption-thrown(classname) exception-catched(classname)

26. Ongoing PHP Dtrace work Probes now integrated within PHP engine – thanks to Wez Furlong and David Soria Parra

27. More probes planned at these places: To track GC events.

28. To track Object create / destroy life cycle.

29. To track Session life cycle. Release sample Dtrace scripts to webstack community.

30. Apache Dtrace Probes accept_connection(uint*) log_request(uint*, char*, char*) receive_request (uint*) create_child() check_user_credentials(uint*) check_access(uint*) check_authorization(uint*)

31. How to try it out ? AMP stack within OpenSolaris 2009.06 includes Dtrace probes. Dtrace probes are integrated within Apache, PHP and MySQL source repository. Available for Solaris 10 as Sun Glassfish Web Stack. http://www.sun.com/webstack Compile yourself MySQL probes are integrated within MySQL 5.4

32. Apache Dtrace probes are available at http://prefetch.net

33. PHP Dtrace probes are integrated within PHP 6.x source tree.

34. Ruby Dtrace probes are integrated within Ruby source.

35. To learn more on DTrace... Dtrace Toolkit (sample scripts) http://www.opensolaris.org/os/community/dtrace/dtracetoolkit/ Dtrace documentation http://www.sun.com/bigadmin/content/dtrace/

36. https://www.opensolaris.org/os/community/dtrace/

37. http://opensolaris.org/os/community/performance/ Apache Dtrace sample scripts http://prefect.net MySQL Dtrace probe documentation: http://dev.mysql.com/doc/refman/6.0/en/dba-dtrace-mysqld-ref.html

38. To learn more on Web Stack... Open Solaris Web Stack Project Home http://www.opensolaris.org/os/project/webstack Apache, Dtrace and MySQL probes are part of Web Stack (OpenSolaris, Solaris 10)

39. PHP Dtrace probes are now documented at http://blogs.sun.com/natarajan/entry/new_dtrace_probes_within_php Sun Web Stack documentation http://wikis.sun.com/display/webstack

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