10.10 Performance Checklist

Many of these suggestions apply only after a bottleneck has been identified:

• Include multithreading at the design stage.

  • Parallelize tasks with threads to speed up calculations.

  • Run slow operations in their own threads to avoid slowing down the main thread.

  • Keep the interface in a separate thread from other work so that the application feels more responsive.

  • Avoid designs and implementations that force points of serialized execution.

  • Use multiple resolution strategies racing in different threads to get quicker answers.

• Avoid locking more resources than necessary.

  • Avoid synchronizing methods of stateless objects.

  • Build classes with synchronized wrappers, and use synchronized versions except when unsynchronized versions are definitely sufficient.

  • Selectively unwrap synchronized wrapped classes to eliminate identified bottlenecks.

  • Avoid synchronized blocks by using thread-specific data structures, combining data only when necessary.

  • Use atomic assignment where applicable.

• Load-balance the application by distributing tasks among multiple threads, using a queue and thread-balancing mechanism for distributing tasks among task-processing threads.

  • Use thread pools to reuse threads if many threads are needed or if threads are needed for very short tasks.

  • Use a thread pool manager to limit the number of concurrent threads used.