Oklahoma City Java Users Group

Lunch Meeting

• When: September 11th, 2007 11:30-12:40
• Where: University of Phoenix (see Meeting location)
• Topic: Concurrency
• Speaker: Brett Schuchert
• Sponsor: Objectmentor

Agenda

• 11:30 am – Welcome Announcements

• 11:40 am – Main Presentation
• 12:40 pm – Wrap Up

Evening Meeting

• When: September 11th, 2007 at 6:00PM
• Where: Computer Club of Oklahoma City (see Meeting location)
• Topic: Concurrency
• Speaker: Brett Schuchert
• Sponsor: Objectmentor

Agenda

• 6:00 pm – Hello Java
• 6:30 pm – Pizza
• 7:00 pm – Welcome Announcements
• 7:15 pm – Main Presentation continued
• 8:45 pm – Giveaways and Wrap Up

Presentation Information

Hello Java

From no-threading to the executor framework built in to Java 5

• This is a quick hop through basic threading.
  • We start with a single-threaded server with a failing test (due to performance).
  • We fix the performance problem by introducing basic threading (justified by the Single Responsibility Principle)
  • We then upgrade the server to us the Executor framework instead hand-rolling threads
  • This is a quick example of creating a fixed-size thread pool
  • If time permits (it probably won't), we'll look at a deadlock problem with the executor framework.

Main Presentation

This presentation assumes familiarity with Java, JUnit 4, and basic Threading – the hello Java should suffice

• We begin with a simple problem of an unguarded, shared resource
  • We fix the problem using synchronized (basic)
  • We fix the problem by NOT guarding (intermediate) using a Java 5 class to do so
  • We then discuss the background behind how this works
• We continue with a real problem, trying to screen scrape some web pages using the HTTP Client. The whole process takes 30 seconds
  • We evaluate the work to figure out
    • The CPU bound parts
    • The I/O bound parts
    • Estimate how much we can speed things up
  • We then test our way into a multi-threaded solution
  • Evaluate the results
  • Remove contention
  • Move towards our theoretical maximum speed
  • Along the way we'll learn a little more about the executor framework
• If we have time (we probably won't), we'll have a look at a few more of the Java 5 classes:
  • Barrier or Latch (haven't picked which one yet)
  • ConcurrentHashMap