More D scripts. Example using ruby-dtrace.

bin/xray_top_10_busiest_code_path_for_process.d

@@ -0,0 +1,12 @@
+#!/usr/sbin/dtrace -s
+#pragma D option quiet
+#pragma D option aggsortrev
+#pragma D option dynvarsize=64m
+#pragma D option ustackframes=64
+#pragma D option strsize=2048
+
+profile-997
+/pid == $target/ 
+{ 
+    @num[ustack()] = count(); 
+}

bin/xray_top_10_busiest_code_path_on_system.d

@@ -0,0 +1,35 @@
+#!/usr/sbin/dtrace -s
+#pragma D option quiet
+#pragma D option dynvarsize=64m
+
+dtrace:::BEGIN 
+{
+    printf("Tracing... Hit Ctrl-C to end.\n");
+    depth = 0;
+}
+
+
+profile-997 
+{
+    @kernel[stack(20)]=count();
+}
+
+
+
+profile-997 
+/arg1/       /* user level PC. Make sure that we are in user space */
+{
+    printf("%d\n", arg1);
+    @userspace[execname, ustack(10)]=count();
+}
+
+END {
+    trunc(@kernel, 10);
+    trunc(@userspace, 10); 
+
+    printf("%s", "\n =========== Top 10 Busiest Kernel Path =============\n");
+    printa(@kernel);
+
+     printf("%s", "\n =========== Top 10 Busiest User Path =============\n");
+     printa(@userspace);
+}

bin/xray_trace_rails_response_times.d

@@ -24,14 +24,14 @@ this string name;
 this string action;
 this string query;
 
-dtrace:::BEGIN
+dtrace:::BEGIN 
 {
     printf("Tracing... Hit Ctrl-C to end.\n");
     depth = 0;
 }
 
 ruby$target::ruby_dtrace_probe:
-/(this->name = copyinstr(arg0)) == "request-start"/
+/(this->name = copyinstr(arg0)) == "request-start"/ 
 {
     self->request_start[copyinstr(arg1)] = timestamp;
 }

examples/dtrace/custom_dtrace_instumentation_using_usdt_probes.rb

@@ -0,0 +1,75 @@
+#!/usr/bin/env ruby -w
+#
+# Define how you can create custom DTrace probes on the fly from
+# Ruby program using the ruby-dtrace gem (USDT provider).
+#
+# Trace all flight search probes with:
+#
+#     sudo dtrace -n 'find-available-flights { printf("%s", copyinstr(arg0)); }'
+#
+# Trace all the flight booking probes with:
+#
+#     sudo dtrace -n 'book { printf("%s %d", copyinstr(arg0), arg1); }'
+#
+require 'rubygems'
+gem "ruby-dtrace"
+require 'dtrace/provider'
+
+#
+# Define custom DTrace USDT probes on the fly using ruby-dtrace
+# native extensions.
+# 
+
+Dtrace::Provider.create :booking_engine do |p|
+  p.probe :boot
+  p.probe :find_available_flights, :string
+  p.probe :book, :string, :integer
+end
+
+#
+# Use these custom probes in your application
+#
+
+
+class BookingEngine
+
+  def find_available_flights(destination)
+    Dtrace::Probe::BookingEngine.find_available_flights do |p|
+      p.fire(destination)
+    end
+    sleep 1  # Some business logic ;-)
+    ["AF98", "JB24"]
+  end
+
+  def book(flight_number, number_of_seats)
+    Dtrace::Probe::BookingEngine.book do |p|
+      p.fire(flight_number, number_of_seats)
+    end
+    sleep 3  # Very slow business logic   
+  end
+
+  def book_all_available_flights
+    find_available_flights("SFO").collect do |flight_number| 
+      book flight_number, rand(10)
+    end
+  end
+
+end
+
+class Application
+
+  def self.boot  
+    # Fire a custom DTrace probe without a block (no start/end concept)
+    Dtrace::Probe::BookingEngine.boot do |p|
+      p.fire
+    end
+
+    booking_engine = BookingEngine.new
+    loop do      
+      booking_engine.book_all_available_flights
+    end
+  end
+
+end
+
+Application.boot

examples/dtrace/simple_ruby_script.rb

@@ -0,0 +1,34 @@
+#!/usr/bin/env ruby -w
+#
+# Simple Ruby script simulating a flight booking engine
+# before we add any custon DTrace instrumentation
+#
+class BookingEngine
+
+  def find_available_flights(destination)
+      sleep 1  # Some business logic ;-)
+      ["AF98", "JB24"]
+  end
+
+  def book(flight_number, number_of_seats)
+      sleep 3  # Very slow business logic   
+  end
+
+  def book_all_available_flights
+      book flight_number, rand(10)
+  end
+
+end
+
+class Application
+
+  def self.boot  
+    booking_engine = BookingEngine.new
+    loop do      
+      booking_engine.book_all_available_flights
+    end
+  end
+
+end
+
+Application.boot

examples/dtrace/simple_ruby_script_with_tracer_custom_dtrace_instrumentation.rb

@@ -0,0 +1,52 @@
+#!/usr/bin/env ruby -w
+#
+# Simple Ruby script demonstrating use of Tracer to install custom
+# (application specific) Dtrace probes.
+# 
+# Run the script, then watch your customn probes fire in another terminal with:
+#
+#     sudo dtrace -n'ruby-probe { printf("%s %s", copyinstr(arg0), copyinstr(arg1)); }'
+#
+require "rubygems"
+require "xray/dtrace/tracer"
+
+class BookingEngine
+  include XRay::DTrace::Tracer
+
+  def find_available_flights(destination)
+    firing "find_available_flights", destination do  
+      sleep 1  # Some business logic ;-)
+      ["AF98", "JB24"]
+    end
+  end
+
+  def book(flight_number)
+    firing "book", flight_number do
+      sleep 3  # Very slow business logic   
+    end
+  end
+
+  def book_all_available_flights
+    find_available_flights("SFO").collect do |flight_number| 
+      book flight_number
+    end
+  end
+
+end
+
+class Application
+  extend DTracer
+
+  def self.boot  
+    # Fire a custom DTrace probe without a block (no start/end concept)
+    fire "boot", Process.pid.to_s
+
+    booking_engine = BookingEngine.new
+    loop do      
+      booking_engine.book_all_available_flights
+    end
+  end
+
+end
+
+Application.boot