rails_conf_notes.org

Debugging ruby performance - Aman Gupta

C, Linux, networks, cpu, and memory usage

• lsof -nPp <pid>
• tcpdump
• write the data to a file, load it up in wireshark
• strace, trace systems calls and signals (jump into kernelspace)
• SIGVTALRM, ruby 1.8 every 10msec to switch threads (green threads)
• posix-spawn instead of fork-exec, check out posix-spawn gem
• ltrace

– ltrace -c ruby foo.rb # summary mode

• memcpy’ing a ton of data on the thread stack
• rbtrace
• rbtrace -p 20052 –slow=50 -m ‘include?(__source__)’
• Google perftools

– – sampling profiler

• perftool.rb (ruby wrapper around google perftools)

– Rack::PerftoolsProfiler (set number of workers down to 1 if using unicorn or passenger)

• gdb.rb !

– where, – ruby eval – ruby objects strings – ruby threads

• memprof
• Memprof.track - takes a block (like bleak_house)
• hotspots (new gem)

– https://github.com/tmm1/hotspots