perftools.txt

Sass
====

Chris Eppstein
@chriseppstein

Compass is on top of sass.

Rationale
Syntax
Best Practices

Sass is a compiler that generates CSS

CoffeeScript by Trevor Burnham at 11:35

Functions, variables, mixins, partials

Performance
===========

Linux:
 * lsof
 * strace
 * ltrace

C code:
 * perftools
 * gdb

Networks:
 * tcpdump
 * ngrep

CPU:
 * bleak_house
 * gdb.rb
 * memprof

Get the slides: http://speakerdeck.com/u/tmm1/p/debugging-ruby-performance

---

lsof (list open files for a pid)
  shows app, ruby, shared libraries, file descriptors (0, 1, 2 are stdin, stdout, stderr)

tcpdump (dump tcp packets)
tcpdump -i eth0 -s 0 -nqA tcp dst port 3306
tcpdump -w <file>, load it up in WireShark

strace (trace system calls and signals)
A system call is a call that happens in system space not user space
-c: count and summarize
-p pid: attach to pid and trace.
stracing ruby: SIGVTALRM is sent every 10 ms (Ruby 1.8)
stracing ruby: sigprocmask
stracing ruby: tests -- result, posix_spawn gem sped up tests by 2x

ltrace (trace library calls)
A library call is a call that happens in user space (C)

rbtrace (trace ruby method calls)
require 'rbtrace'
rbtrace -p pid -m method
rbtrace -c <predefinedtracer>

perftools (Google's performance tools), a suite
CPUPROFILE, pprof

perftools.rb (perftools for Ruby code)
github.com/tmm1/perftools.rb
Can do "wall-clock" time
Can also count objects created

rack-perftools (rack middleware for perftools.rb)
Adds URLs to your app (?profile=true)

gdb (the GNU debugger)
gdb <executable>
gdb <executable> <pid>
  "where" "backtrace"

gdb.rb (gdb with MRI hooks)
gem install gdb.rb
  "ruby objects classes"

memprof (heap visualizer for ruby)
analyze json output with mongodb/couchdb, jsawk/grep

memprof.com

"ab" tool

hotspots (a performance tool for rails)