dtrace

~ ➔  sudo dtrace -l -n "ruby*:::"
Password:
   ID   PROVIDER            MODULE                          FUNCTION NAME
179470  ruby16991             mymod                              myfn probe
~ ➔  sudo dtrace -l -n "ruby*:::"
   ID   PROVIDER            MODULE                          FUNCTION NAME
dtrace: failed to match ruby*:::: No probe matches description
~ ➔  sudo dtrace -l -n "ruby*:::"
   ID   PROVIDER            MODULE                          FUNCTION NAME
 1074  ruby16991             mymod                              myfn probe
 1075  ruby16991             mymod                             myfn2 probe
~ ➔  sudo dtrace -l -n "ruby*:::"
   ID   PROVIDER            MODULE                          FUNCTION NAME
 1074  ruby16991             mymod                              myfn probe
 1075  ruby16991             mymod                             myfn2 probe
 1076  ruby16991             mymod                             myfn3 probe

irb

1.9.2-p290 :001 > require 'usdt'
 => true 
1.9.2-p290 :002 > provider = USDT::Provider.create :ruby, :mymod
 => #<USDT::Provider:0x000001014bde60> 
1.9.2-p290 :003 > p = provider.probe(:myfn, :probe, :string, :string, :integer)
 => #<USDT::Probe:0x000001014a7958> 
1.9.2-p290 :004 > provider.enable
 => true 
1.9.2-p290 :005 > provider.disable
 => true 
1.9.2-p290 :006 > p2 = provider.probe(:myfn2, :probe, :string, :string, :integer)
 => #<USDT::Probe:0x00000101476858> 
1.9.2-p290 :007 > provider.enable
 => true 
1.9.2-p290 :008 > provider.disable
 => true 
1.9.2-p290 :009 > p3 = provider.probe(:myfn3, :probe, :string, :string, :integer)
 => #<USDT::Probe:0x0000010144df98> 
1.9.2-p290 :010 > provider.enable
 => true