Debugging Ruby Performance

Ruby might be slow, but bad code only makes it worse. This talk will teach you how to use powerful tools to see how your code is executed, so you can understand, debug and optimize it.

Transcript

1. DEBUGGING RUBY PERFORMANCE Aman Gupta @tmm1 speakerdeck.com/u/tmm1/p/debugging-ruby-performance
2. AS RUBYISTS, WE'VE SEEN...
3. ejpphoto (flickr) nasty bugs
4. code fatboyke (flickr)
5. 37prime (flickr) memory bloat
6. THIS TALK IS ABOUT... TOOLS TO FIX THESE ISSUES.
7. TOOLS FOR LINUX. pleeker (flickr) lsof strace ltrace
8. TOOLS FOR C CODE. booddin (flickr) perftools gdb
9. pascal.charest (flickr) TOOLS FOR NETWORKS. tcpdump ngrep
10. marksze (flickr) TOOLS FOR CPU USAGE. perftools perftools.rb
11. kgrocki (flickr) TOOLS FOR MEMORY USAGE. bleak_house gdb.rb memprof
12. mayu (flickr) delgrossodotcom (flickr) IGNORE THE FINE PRINT
13. list open files LSOF lsof -nPp <pid>
14. lsof -nPp <pid> -n Inhibits the conversion of network numbers to host names. -P Inhibits the conversion of port numbers to names for network files FD TYPE NAME cwd DIR /var/www/myapp txt REG /usr/bin/ruby mem REG /json-1.1.9/ext/json/ext/generator.so mem REG /json-1.1.9/ext/json/ext/parser.so mem REG /memcached-0.17.4/lib/rlibmemcached.so mem REG /mysql-2.8.1/lib/mysql_api.so 0u CHR /dev/null 1w REG /usr/local/nginx/logs/error.log 2w REG /usr/local/nginx/logs/error.log 3u IPv4 10.8.85.66:33326->10.8.85.68:3306 (ESTABLISHED) 10u IPv4 10.8.85.66:33327->10.8.85.68:3306 (ESTABLISHED) 11u IPv4 127.0.0.1:58273->127.0.0.1:11211 (ESTABLISHED) 12u REG /tmp/RackMultipart.28957.0 33u IPv4 174.36.83.42:37466->69.63.180.21:80 (ESTABLISHED) json memcached mysql http
15. dump traffic on a network TCPDUMP tcpdump -i eth0 -s 0 -nqA tcp dst port 3306
16. tcpdump -i <eth> -s <len> -nqA <expr> -i <eth> Network interface. -s <len> Snarf len bytes of data from each packet. -n Don't convert addresses (host addresses, port numbers) to names. -q Quiet output. Print less protocol information. -A Print each packet (minus its link level header) in ASCII. -w <file> Write the raw packets to file rather than printing them out. <expr> libpcap expression, for example: tcp src port 80 tcp dst port 3306 tcpdump -i <eth> -w <file> <expr>
17. tcp dst port 80 19:52:20.216294 IP 24.203.197.27.40105 > 174.37.48.236.80: tcp 438 E...*.@.l.%&.....%0....POx..%s.oP....... GET /poll_images/cld99erh0/logo.png HTTP/1.1 Accept: */* Referer: http://apps.facebook.com/realpolls/? _fb_q=1
18. tcp dst port 3306 19:51:06.501632 IP 10.8.85.66.50443 > 10.8.85.68.3306: tcp 98 E..."K@.@.Yy .UB .UD.....z....L............ GZ.y3b..[......W.... SELECT * FROM `votes` WHERE (`poll_id` = 72621) LIMIT 1
19. tcpdump -w <file>
20. trace system calls and signals STRACE strace -cp <pid> strace -ttTp <pid> -o <file>
21. strace -cp <pid> -c Count time, calls, and errors for each system call and report a summary on program exit. -p pid Attach to the process with the process ID pid and begin tracing. % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 50.39 0.000064 0 1197 592 read 34.65 0.000044 0 609 writev 14.96 0.000019 0 1226 epoll_ctl 0.00 0.000000 0 4 close 0.00 0.000000 0 1 select 0.00 0.000000 0 4 socket 0.00 0.000000 0 4 4 connect 0.00 0.000000 0 1057 epoll_wait ------ ----------- ----------- --------- --------- ---------------- 100.00 0.000127 4134 596 total
22. strace -ttTp <pid> -o <file> -t Prefix each line of the trace with the time of day. -tt If given twice, the time printed will include the microseconds. -T Show the time spent in system calls. -o filename Write the trace output to the file filename rather than to stderr. epoll_wait(9, {{EPOLLIN, {u32=68841296, u64=68841296}}}, 4096, 50) = 1 <0.033109> accept(10, {sin_port=38313, sin_addr="127.0.0.1"}, [1226]) = 22 <0.000014> fcntl(22, F_GETFL) = 0x2 (flags O_RDWR) <0.000007> fcntl(22, F_SETFL, O_RDWR|O_NONBLOCK) = 0 <0.000008> setsockopt(22, SOL_TCP, TCP_NODELAY, [1], 4) = 0 <0.000008> accept(10, 0x7fff5d9c07d0, [1226]) = -1 EAGAIN <0.000014> epoll_ctl(9, EPOLL_CTL_ADD, 22, {EPOLLIN, {u32=108750368, u64=108750368}}) = 0 <0.000009> epoll_wait(9, {{EPOLLIN, {u32=108750368, u64=108750368}}}, 4096, 50) = 1 <0.000007> read(22, "GET / HTTP/1.1\r"..., 16384) = 772 <0.000012> rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 <0.000007> poll([{fd=5, events=POLLIN|POLLPRI}], 1, 0) = 0 (Timeout) <0.000008> write(5, "1\0\0\0\0\0\0-\0\0\0\3SELECT * FROM `table`"..., 56) = 56 <0.000023> read(5, "\25\1\0\1,\2\0x\234m"..., 16384) = 284 <1.300897>
23. read(22, "GET / HTTP/1.1\r"..., 16384) = 772 <0.0012> http client connection read 772 bytes incoming http request took 0.0012s
24. write(5, "SELECT * FROM `table`"..., 56) = 56 <0.0023> read(5, "\25\1\0\1,\2\0x\234m"..., 16384) = 284 <1.30> mysql connection write sql query to db read query response slow query
25. stracing ruby: SIGVTALRM --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- rt_sigreturn(0x1a) = 2207807 <0.000009> --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- rt_sigreturn(0x1a) = 0 <0.000009> --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- rt_sigreturn(0x1a) = 140734552062624 <0.000009> --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- rt_sigreturn(0x1a) = 140734552066688 <0.000009> --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- rt_sigreturn(0x1a) = 11333952 <0.000008> --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- rt_sigreturn(0x1a) = 0 <0.000009> --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- rt_sigreturn(0x1a) = 1 <0.000010> --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- • ruby 1.8 uses signals to schedule its green threads • process receives a SIGVTALRM signal every 10ms
26. stracing ruby: sigprocmask • debian/redhat compile ruby with --enable-pthread • uses a native thread timer for SIGVTALRM • causes excessive calls to sigprocmask: 30% slowdown! % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 100.00 0.326334 0 3568567 rt_sigprocmask 0.00 0.000000 0 9 read 0.00 0.000000 0 10 open 0.00 0.000000 0 10 close 0.00 0.000000 0 9 fstat 0.00 0.000000 0 25 mmap ------ ----------- ----------- --------- --------- ---------------- 100.00 0.326334 3568685 0 total
27. % time seconds calls syscall ------ ----------- ------ ------- 95.94 76.685658 1086 clone 95s in the github test suite in clone() `git cmd` calls fork() which calls clone() posix-spawn gem sped up tests by 2x! stracing ruby: tests
28. trace library calls LTRACE ltrace -cp <pid> ltrace -ttTp <pid> -o <file>
29. % time seconds usecs/call calls function ------ ----------- ----------- --------- -------------------- 48.65 11.741295 617 19009 memcpy 30.16 7.279634 831 8751 longjmp 9.78 2.359889 135 17357 _setjmp 8.91 2.150565 285 7540 malloc 1.10 0.265946 20 13021 memset 0.81 0.195272 19 10105 __ctype_b_loc 0.35 0.084575 19 4361 strcmp 0.19 0.046163 19 2377 strlen 0.03 0.006272 23 265 realloc ------ ----------- ----------- --------- -------------------- 100.00 24.134999 82999 total ltrace -c ruby threaded_em.rb 01:24:48.769408 --- SIGVTALRM (Virtual timer expired) --- 01:24:48.769616 memcpy(0x1216000, "", 1086328) = 0x1216000 <0.000578> 01:24:48.770555 memcpy(0x6e32670, "\240&\343v", 1086328) = 0x6e32670 <0.000418> 01:24:49.899414 --- SIGVTALRM (Virtual timer expired) --- 01:24:49.899490 memcpy(0x1320000, "", 1082584) = 0x1320000 <0.000628> 01:24:49.900474 memcpy(0x6e32670, "", 1086328) = 0x6e32670 <0.000479> ltrace -ttT -e memcpy ruby threaded_em.rb
30. trace ruby method calls RBTRACE require 'rbtrace' rbtrace -p <pid> -m <method> github.com/tmm1/rbtrace
31. Unicorn::App#call(env['PATH_INFO']="/cakephp/cakephp/downloads") Smoke::Git#cat_ref(args=["2.0.0-dev"]) <0.046590> Smoke::Git#cat_ref(args=["1.3-dev"]) <0.053170> Smoke::Git#cat_ref(args=["1.3.7"]) <0.046643> Smoke::Git#cat_ref(args=["1.3.6"]) <0.045075> Smoke::Git#cat_ref(args=["1.3.5"]) <0.043925> Smoke::Git#cat_ref(args=["1.3.4"]) <0.054496> Smoke::Git#cat_ref(args=["1.3.3"]) <0.045860> rbtrace -p <PID> -m "Unicorn::App#call(env['PATH_INFO'])" "Smoke::Git#(args)" downloads page makes N+1 git calls to resolve tags
32. $ rbtrace -p 20052 --slow=50 *** attached to process 20052 Array#include? <0.075737> Array#include? <0.077302> Array#include? <0.076444> Array#include? <0.077122> Array#include? <0.074956> $ rbtrace -p 20052 --slow=50 -m 'include?(__source__)' *** attached to process 20052 Array#include?(__source__="lib/jekyll/site.rb:179") <0.075737> Array#include?(__source__="lib/jekyll/site.rb:179") <0.077302> Array#include?(__source__="lib/jekyll/site.rb:179") <0.076444> slow jekyll processing fixed by switching to Set#include?
33. Albino#colorize(@target.size=180, @options[:l]="plain") <0.151861> Albino#colorize(@target.size=1009, @options[:l]="ruby") <0.233931> Albino#colorize(@target.size=9024, @options[:l]="js") <0.278415> Albino#colorize(@target.size=243, @options[:l]="plain") <0.155549> Albino#colorize(@target.size=596, @options[:l]="diff") <0.169390> Albino#colorize(@target.size=2994, @options[:l]="ruby") <0.305385> Albino#colorize(@target.size=2372, @options[:l]="js") <0.227131> Albino#colorize(@target.size=42444, @options[:l]="php") <0.448636> Albino#colorize(@target.size=1795, @options[:l]="ruby") <0.259931> Albino#colorize(@target.size=3088, @options[:l]="plain") <0.480678> ~500ms to shell out to python pygmentize use pygments.rb for 15x faster syntax highlighting! (uses FFI to embed python inside ruby)
34. rbtrace -c <predefined tracer> MysqlAdapter#execute(sql="SELECT * FROM `users` WHERE (`users`.`id` = 105775) ") <0.000472> MysqlAdapter#execute(sql="SELECT * FROM `gists` WHERE (`gists`.`public` = 1 AND `gists`.`id` = '871708' ) LIMIT 1") <0.002153> MysqlAdapter#execute(sql="SELECT count(*) AS count_all FROM `gist_comments` WHERE (`gist_comments`.gist_id = 871708) ") <0.000866> Redis::Client#process(commands=[[:zscore, "gwiki:597840:updated", ["home"]]]) <0.000439> Redis::Client#process(commands=[[:get, "gh.storage.network.1745996"]]) <0.000923> Redis::Client#process(commands=[[:sismember, "gh:beta:users", "14850"]]) <0.000520> Redis::Client#process(commands=[[:rpush, "resque:queue:high", "{...}"]]) <0.000428> built-in tracers for activerecord, redis, mongo, eventmachine, unicorn, testunit
35. google's performance tools PERFTOOLS CPUPROFILE=/tmp/myprof ./myapp pprof ./myapp /tmp/myprof
36. wget http://google-perftools.googlecode.com/files/google- perftools-1.6.tar.gz tar zxvf google-perftools-1.6.tar.gz cd google-perftools-1.6 ./configure --prefix=/opt make sudo make install # for linux export LD_PRELOAD=/opt/lib/libprofiler.so # for osx export DYLD_INSERT_LIBRARIES=/opt/lib/libprofiler.dylib CPUPROFILE=/tmp/ruby.prof ruby -e' 5_000_000.times{ "hello world" } ' pprof `which ruby` --text /tmp/ruby.prof download compile profile report setup
37. Total: 103 samples 95 92.2% rb_yield_0 103 100.0% rb_eval 12 11.7% gc_sweep 52 50.5% rb_str_new3 3 2.9% obj_free 103 100.0% int_dotimes 12 11.7% gc_mark pprof ruby ruby.prof --text pprof ruby ruby.prof --gif
38. Profiling MRI • 10% of production VM time spent in rb_str_sub_bang • String#sub! • called from Time.parse return unless str.sub!(/\A(\d{1,2})/, '') return unless str.sub!(/\A( \d|\d{1,2})/, '') return unless str.sub!(/\A( \d|\d{1,2})/, '') return unless str.sub!(/\A(\d{1,3})/, '') return unless str.sub!(/\A(\d{1,2})/, '') return unless str.sub!(/\A(\d{1,2})/, '')
39. Profiling EM + threads • known issue: EM+threads = slow • memcpy?? • thread context switches copy the stack w/ memcpy • EM allocates huge buffer on the stack • solution: move buffer to the heap Total: 3763 samples 2764 73.5% catch_timer 989 26.3% memcpy 3 0.1% st_lookup 2 0.1% rb_thread_schedule 1 0.0% rb_eval 1 0.0% rb_newobj 1 0.0% rb_gc_force_recycle
40. perftools for ruby code PERFTOOLS.RB pprof.rb /tmp/myrbprof github.com/tmm1/perftools.rb
41. gem install perftools.rb RUBYOPT="-r`gem which perftools | tail -1`" CPUPROFILE=/tmp/myrbprof ruby myapp.rb pprof.rb /tmp/myrbprof --text pprof.rb /tmp/myrbprof --gif > /tmp/myrbprof.gif
42. • Sampling profiler: • 232 samples total • 83 samples were in /compute • 118 samples had /compute on the stack but were in another function • /compute accounts for 50% of process, but only 35% of time was in /compute itself require 'sinatra' get '/sleep' do sleep 0.25 'done' end get '/compute' do proc{ |n| a,b=0,1 n.times{ a,b = b,a+b } b }.call(10_000) 'done' end $ ab -c 1 -n 50 http://127.0.0.1:4567/compute $ ab -c 1 -n 50 http://127.0.0.1:4567/sleep == Sinatra has ended his set (crowd applauds) PROFILE: interrupts/evictions/bytes = 232/0/2152 Total: 232 samples 83 35.8% 35.8% 118 50.9% Sinatra::Application#GET /compute 56 24.1% 59.9% 56 24.1% garbage_collector 35 15.1% 75.0% 113 48.7% Integer#times
43. CPUPROFILE=app.prof CPUPROFILE_REALTIME=1 CPUPROFILE=app-rt.prof
44. redis-rb bottleneck
45. why is rubygems slow?
46. slow nanite tests
47. faster bundle install • 23% spent in Gem::Version#<=> • simple patch to rubygems improved overall install performance by 15% • http://gist.github.com/ 458185
48. CPUPROFILE_OBJECTS=1 CPUPROFILE=app-objs.prof • object allocation profiler mode built-in • 1 sample = 1 object created • Time parsing is both CPU and object allocation intensive • using mysql2 moves this to C
49. rack middleware for perftools.rb RACK-PERFTOOLS gem install rack- perftools_profiler github.com/bhb/rack-perftools_profiler
50. require 'rack/perftools_profiler' config.middleware.insert( 0, Rack::PerftoolsProfiler, :default_printer => 'gif' ) $ curl http://localhost:3000/__start__ $ curl http://localhost:3000/home $ curl http://localhost:3000/about $ curl http://localhost:3000/__stop__ $ curl http://localhost:3000/__data__ -o profile.gif $ curl http://localhost:3000/__data__?printer=text -o profile.txt $ curl "http://localhost:3000/home?profile=true&times=10" -o 10_requests_to_homepage.gif
51. the GNU debugger GDB gdb <executable> gdb attach <pid>
52. Debugging Ruby Segfaults #include "ruby.h" VALUE segv() { VALUE array[1]; array[1000000] = NULL; return Qnil; } void Init_segv() { rb_define_method(rb_cObject, "segv", segv, 0); } test_segv.rb:4: [BUG] Segmentation fault ruby 1.8.7 (2008-08-11 patchlevel 72) [i686-darwin9.7.0] def test require 'segv' 4.times do Dir.chdir '/tmp' do Hash.new{ segv }[0] end end end sleep 10 test()
53. 1. Attach to running process $ sudo gdb ruby 23611 Attaching to program: ruby, process 23611 0x00007fa5113c0c93 in nanosleep () from /lib/libc.so.6 (gdb) c Continuing. Program received signal SIGBUS, Bus error. segv () at segv.c:7 7 array[1000000] = NULL; $ ps aux | grep ruby joe 23611 0.0 0.1 25424 7540 S Dec01 0:00 ruby test_segv.rb 2. Use a coredump $ sudo mkdir /cores $ sudo chmod 777 /cores $ sudo sysctl kernel.core_pattern=/cores/%e.core.%s.%p.%t Process.setrlimit Process::RLIMIT_CORE, 300*1024*1024 $ sudo gdb ruby /cores/ruby.core.6.23611.1259781224
54. def test require 'segv' 4.times do Dir.chdir '/tmp' do Hash.new{ segv }[0] end end end test() (gdb) where #0 segv () at segv.c:7 #1 0x000000000041f2be in call_cfunc () at eval.c:5727 ... #13 0x000000000043ba8c in rb_hash_default () at hash.c:521 ... #19 0x000000000043b92a in rb_hash_aref () at hash.c:429 ... #26 0x00000000004bb7bc in chdir_yield () at dir.c:728 #27 0x000000000041d8d7 in rb_ensure () at eval.c:5528 #28 0x00000000004bb93a in dir_s_chdir () at dir.c:816 ... #35 0x000000000041c444 in rb_yield () at eval.c:5142 #36 0x0000000000450690 in int_dotimes () at numeric.c:2834 ... #48 0x0000000000412a90 in ruby_run () at eval.c:1678 #49 0x000000000041014e in main () at main.c:48
55. gdb with MRI hooks GDB.RB gem install gdb.rb gdb.rb <pid> github.com/tmm1/gdb.rb
56. (gdb) ruby eval 1+2 3 (gdb) ruby eval Thread.current #<Thread:0x1d630 run> (gdb) ruby eval Thread.list.size 8
57. (gdb) ruby threads list 0x15890 main thread THREAD_STOPPED WAIT_JOIN(0x19ef4) 0x19ef4 thread THREAD_STOPPED WAIT_TIME(57.10s) 0x19e34 thread THREAD_STOPPED WAIT_FD(5) 0x19dc4 thread THREAD_STOPPED WAIT_NONE 0x19dc8 thread THREAD_STOPPED WAIT_NONE 0x19dcc thread THREAD_STOPPED WAIT_NONE 0x22668 thread THREAD_STOPPED WAIT_NONE 0x1d630 curr thread THREAD_RUNNABLE WAIT_NONE
58. (gdb) ruby objects HEAPS 8 SLOTS 1686252 LIVE 893327 (52.98%) FREE 792925 (47.02%) scope 1641 (0.18%) regexp 2255 (0.25%) data 3539 (0.40%) class 3680 (0.41%) hash 6196 (0.69%) object 8785 (0.98%) array 13850 (1.55%) string 105350 (11.79%) node 742346 (83.10%)
59. (gdb) ruby objects strings 140 u'lib' 158 u'0' 294 u'\n' 619 u'' 30503 unique strings 3187435 bytes
60. def test require 'segv' 4.times do Dir.chdir '/tmp' do Hash.new{ segv }[0] end end end test() (gdb) ruby threads 0xa3e000 main curr thread THREAD_RUNNABLE WAIT_NONE node_vcall segv in test_segv.rb:5 node_call test in test_segv.rb:5 node_call call in test_segv.rb:5 node_call default in test_segv.rb:5 node_call [] in test_segv.rb:5 node_call test in test_segv.rb:4 node_call chdir in test_segv.rb:4 node_call test in test_segv.rb:3 node_call times in test_segv.rb:3 node_vcall test in test_segv.rb:9
61. rails_warden leak (gdb) ruby objects classes 1197 MIME::Type 2657 NewRelic::MetricSpec 2719 TZInfo::TimezoneTransitionInfo 4124 Warden::Manager 4124 MethodOverrideForAll 4124 AccountMiddleware 4124 Rack::Cookies 4125 ActiveRecord::ConnectionAdapters::ConnectionManagement 4125 ActionController::Session::CookieStore 4125 ActionController::Failsafe 4125 ActionController::ParamsParser 4125 Rack::Lock 4125 ActionController::Dispatcher 4125 ActiveRecord::QueryCache 4125 ActiveSupport::MessageVerifier 4125 Rack::Head middleware chain leaking per request
62. mongrel sleeper thread 0x16814c00 thread THREAD_STOPPED WAIT_TIME(0.47) 1522 bytes node_fcall sleep in lib/mongrel/configurator.rb:285 node_fcall run in lib/mongrel/configurator.rb:285 node_fcall loop in lib/mongrel/configurator.rb:285 node_call run in lib/mongrel/configurator.rb:285 node_call initialize in lib/mongrel/configurator.rb:285 node_call new in lib/mongrel/configurator.rb:285 node_call run in bin/mongrel_rails:128 node_call run in lib/mongrel/command.rb:212 node_call run in bin/mongrel_rails:281 node_fcall (unknown) in bin/mongrel_rails:19 def run @listeners.each {|name,s| s.run } $mongrel_sleeper_thread = Thread.new { loop { sleep 1 } } end
63. god memory leaks (gdb) ruby objects arrays elements instances 94310 3 94311 3 94314 2 94316 1 5369 arrays 2863364 member elements many arrays with 90k+ elements! 5 separate god leaks fixed by Eric Lindvall with the help of gdb.rb! 43 God::Process 43 God::Watch 43 God::Driver 43 God::DriverEventQueue 43 God::Conditions::MemoryUsage 43 God::Conditions::ProcessRunning 43 God::Behaviors::CleanPidFile 45 Process::Status 86 God::Metric 327 God::System::SlashProcPoller 327 God::System::Process 406 God::DriverEvent
64. a heap visualizer for ruby MEMPROF gem install memprof open http://memprof.com github.com/ice799/memprof
65. • memprof.track • memprof.dump • memprof.dump_all • memprof.com memprof features
66. Memprof.track{ 100.times{ "abc" } 100.times{ 1.23 + 1 } 100.times{ Module.new } } 100 file.rb:2:String 100 file.rb:3:Float 100 file.rb:4:Module • like bleak_house, but for a given block of code • use Memprof::Middleware in your webapps to run track per request
67. • memprof.track • memprof.dump • memprof.dump_all • memprof.com memprof features
68. { "_id": "0x19c610", "file": "file.rb", "line": 2, "type": "string", "class": "0x1ba7f0", "class_name": "String", "length": 10, "data": "helloworld" } memory address of object file and line where string was created length and contents of this string instance address of the class “String” strings Memprof.dump{ "hello" + "world" }
69. floats and strings are separate ruby objects { "_id": "0x19c5c0", "class": "0x1b0d18", "class_name": "Array", "length": 4, "data": [ 1, ":b", "0x19c750", "0x19c598" ] } integers and symbols are stored in the array itself arrays Memprof.dump{ [ 1, :b, 2.2, "d" ] }
70. hashes { "_id": "0x19c598", "type": "hash", "class": "0x1af170", "class_name": "Hash", "default": null, "length": 2, "data": [ [ ":a", 1 ], [ "0xc728", "0xc750" ] ] } hash entries as key/value pairs no default proc Memprof.dump{ { :a => 1, "b" => 2.2 } }
71. classes Memprof.dump{ class Hello @@var=1 Const=2 def world() end end } { "_id": "0x19c408", "type": "class", "name": "Hello", "super": "0x1bfa48", "super_name": "Object", "ivars": { "@@var": 1, "Const": 2 }, "methods": { "world": "0x19c318" } } class variables and constants are stored in the instance variable table superclass object reference references to method objects
72. • memprof.track • memprof.dump • memprof.dump_all • memprof.com memprof features
73. Memprof.dump_all("myapp_heap.json") • dump out every single live object as json • one per line to specified file • analyze via • jsawk/grep • mongodb/couchdb • custom ruby scripts • libyajl + Boost Graph Library
74. • memprof.track • memprof.dump • memprof.dump_all • memprof.com memprof features
75. a web-based heap visualizer and leak analyzer memprof.com
76. plugging a leak in rails3 • in dev mode, rails3 is leaking 10mb per request # in environment.rb require `gem which memprof/signal`.strip let’s use memprof to find it!
77. plugging a leak in rails3 tell memprof to dump out the entire heap to json $ memprof --pid <pid> --name <dump name> --key <api key> send the app some requests so it leaks $ ab -c 1 -n 30 http://localhost:3000/
78. 2519 classes 30 copies of TestController mongo query for all TestController classes details for one copy of TestController
79. find references to object holding references to all controllers “leak” is on line 178
80. • In development mode, Rails reloads all your application code on every request • ActionView::Partials::PartialRenderer is caching partials used by each controller as an optimization • But.. it ends up holding a reference to every single reloaded version of those controllers
81. a performance tool for rails HOTSPOTS gem install hotspots hotspots /tmp/*.json report/ github.com/tmm1/hotspots
82. config.middleware.use(Memprof::Tracer) { "time": 4.3442, "rails": { "controller": "test", "action": "index" }, "request": { "REQUEST_PATH": "/test", "REQUEST_METHOD": "GET" }, total time for request rails controller/action request env info
83. "mysql": { "queries": 3, "time": 0.00109302 }, "gc": { "calls": 8, "time": 2.04925 }, config.middleware.use(Memprof::Tracer) 8 calls to GC 2 secs spent in GC 3 mysql queries config.middleware.use(Memprof::Tracer)
84. "objects": { "created": 3911103, "types": { "none": 1168831, "object": 1127, "float": 627, "string": 1334637, "array": 609313, "hash": 3676, "match": 70211 } } } config.middleware.use(Memprof::Tracer) 3 million objs created lots of strings lots of arrays regexp matches object instances 1 million method calls config.middleware.use(Memprof::Tracer)
85. Requests over time
86. Top controllers and actions
87. Request and response types
88. Response time breakdown
89. Garbage Collection overhead
90. Objects created per request
91. SQL queries and types
92. time-series analytics GRAPHITE ./carbon-cache.py start gunicorn_django launchpad.net/graphite
93. collectd: frontend load
94. collectd: frontend cpu usage
95. collectd: all frontend cpu usage
96. custom metrics: unicorn requests diff = Time.now - @start $stats.timing("unicorn.#{host}.response_time", diff * 1000)
97. custom metrics: unicorn response time
98. custom metrics: unicorn response time
99. custom metrics: unicorn GC time
100. custom metrics: deployments
101. custom metrics: deployments
102. custom metrics: GitHub for Mac $stats.increment('macapp.install')
103. custom metrics: merge button
104. custom metrics: merge button
105. custom metrics: github users!
106. custom metrics: github users!
107. TOOLS MAKE DEBUGGING EASIER.
108. LSOF TCPDUMP STRACE LTRACE RBTRACE GDB GDB.RB PERFTOOLS PERFTOOLS.RB RACK-PERFTOOLS MEMPROF HOTSPOTS GRAPHITE
109. LEARN THESE TOOLS. USE THESE TOOLS. yujie (flickr)
110. QUESTIONS? Aman Gupta @tmm1 speakerdeck.com/u/tmm1/p/debugging-ruby-performance