rack_dump.sh

#!/bin/sh

# Create a temporary file which will hold the GDB Commands
TMPFILE=`mktemp /tmp/gdbcommands.XXXXXX` || exit 1

# Add commands to the newly created file
cat <<-EOF > $TMPFILE
define redirect_stdout
  call rb_eval_string("\$_old_stdout, \$stdout = \$stdout, File.open('/tmp/ruby-debug.' + Process.pid.to_s, 'a'); \$stdout.sync = true")
end

define ruby_eval
  call(rb_p(rb_eval_string_protect(\$arg0,(int*)0)))
end

redirect_stdout
ruby_eval("Kernel.caller")
quit
EOF

# Fetch all 'Rack' process pids
RACK_PIDS=$(pgrep -f Rack)

# Dump stacktrace from all 'Rack' processes
# Stacktrace will be available in /tmp/ruby-debug.PID
for RACK_PID in $RACK_PIDS
do
   sudo gdb --batch-silent -x $TMPFILE ruby $RACK_PID
done

# Kill all 'dumped' Passenger processes
sudo kill -9 $RACK_PIDS

# Remove temporary config file
rm $TMPFILE