mfazekas/dtrace_scripts.md

## dtrace_scripts.md

      
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              dtrace_scripts.md
            
          
    rails hanged, why?

see what's ruby functions running

process id is 928
sudo dtrace -n \
  'ruby*:::method-entry {  printf("-> %s %s\n",copyinstr(arg0),copyinstr(arg1)) }' \
  -p 928
stats by function call (pressing ctrl+c should dump the stats)

sudo dtrace -n \
  'ruby*:::method-entry { @[copyinstr(arg0), copyinstr(arg1)] = count() }' \
  -p 928
use lldb to call rb_backtrace

lldb
(lldb) attach pid
(gdb) call (void)rb_backtrace()