1BListing and Image Index Listing and Image Index Preface Y Listing 1.Bad Way to Sort a List.Don't Do this. xiv Listing 2.Less than Optimal Way to Sort a List. y Chapter 1.Introduction 11 Listing 1.1.Non-thread-safe Sequence Generator 5 Figure 1.1.Unlucky Execution of Unsafesequence.Nextvalue. 5 Listing 1.2.Thread-safe Sequence Generator. 6 Chapter 2.Thread Safety 11 Listing 2.1.A Stateless Servlet. 13 Listing 2.2.Servlet that Counts Requests without the Necessary Synchronization.Don't Do this. 14 Listing 2.3.Race Condition in Lazy Initialization.Don't Do this. 15 Listing 2.4.Servlet that Counts Requests Using Atomi cLonq. 16 Listing 2.5.Servlet that Attempts to Cache its Last Result without Adequate Atomicity.Don't Do this. 17 Listing 2.6.Servlet that Caches Last Result,But with Unacceptably Poor Concurrency.Don't Do this. 18 Listing 2.7.Code that would Deadlock if Intrinsic Locks were Not Reentrant. 18 Figure 2.1.Poor Concurrency of SynchronizedFactorizer. 21 Listing 2.8.Servlet that Caches its Last Request and Result. 21 Chapter 3.Sharing Objects 23 Listing 3.1.Sharing Variables without Synchronization.Don't Do this. 23 Listing 3.2.Non-thread-safe Mutable Integer Holder. 24 Listing 3.3.Thread-safe Mutable Integer Holder. 24 Figure 3.1.Visibility Guarantees for Synchronization. 25 Listing 3.4.Counting Sheep. 26 Listing 3.5.Publishing an Object. 27 Listing 3.6.Allowing Internal Mutable State to Escape.Don't Do this. 21 Listing 3.7.Implicitly Allowing the this Reference to Escape.Don't Do this. 28 Listing 3.8.Using a Factory Method to Prevent the this Reference from Escaping During Construction. 28 Listing 3.9.Thread Confinement of Local Primitive and Reference Variables. 30 Listing 3.10.Using ThreadLocal to Ensure thread Confinement. 30 Listing 3.11.Immutable Class Built Out of Mutable Underlying Objects 32 Listing 3.12.Immutable Holder for Caching a Number and its Factors. 33 Listing 3.13.Caching the Last Result Using a Volatile Reference to an Immutable Holder Object. 33 Listing 3.14.Publishing an Object without Adequate Synchronization.Don't Do this. 331BListing and Image Index v Listing and Image Index Preface v Listing 1. Bad Way to Sort a List. Don't Do this. xiv Listing 2. Less than Optimal Way to Sort a List. xv Chapter 1. Introduction 11 Listing 1.1. NonͲthreadͲsafe Sequence Generator. 5 Figure 1.1. Unlucky Execution of UnsafeSequence.Nextvalue. 5 Listing 1.2. ThreadͲsafe Sequence Generator. 6 Chapter 2. Thread Safety 11 Listing 2.1. A Stateless Servlet. 13 Listing 2.2. Servlet that Counts Requests without the Necessary Synchronization. Don't Do this. 14 Listing 2.3. Race Condition in Lazy Initialization. Don't Do this. 15 Listing 2.4. Servlet that Counts Requests Using AtomicLong. 16 Listing 2.5. Servlet that Attempts to Cache its Last Result without Adequate Atomicity. Don't Do this. 17 Listing 2.6. Servlet that Caches Last Result, But with Unacceptably Poor Concurrency. Don't Do this. 18 Listing 2.7. Code that would Deadlock if Intrinsic Locks were Not Reentrant. 18 Figure 2.1. Poor Concurrency of SynchronizedFactorizer. 21 Listing 2.8. Servlet that Caches its Last Request and Result. 21 Chapter 3. Sharing Objects 23 Listing 3.1. Sharing Variables without Synchronization. Don't Do this. 23 Listing 3.2. NonͲthreadͲsafe Mutable Integer Holder. 24 Listing 3.3. ThreadͲsafe Mutable Integer Holder. 24 Figure 3.1. Visibility Guarantees for Synchronization. 25 Listing 3.4. Counting Sheep. 26 Listing 3.5. Publishing an Object. 27 Listing 3.6. Allowing Internal Mutable State to Escape. Don't Do this. 27 Listing 3.7. Implicitly Allowing the this Reference to Escape. Don't Do this. 28 Listing 3.8. Using a Factory Method to Prevent the this Reference from Escaping During Construction. 28 Listing 3.9. Thread Confinement of Local Primitive and Reference Variables. 30 Listing 3.10. Using ThreadLocal to Ensure thread Confinement. 30 Listing 3.11. Immutable Class Built Out of Mutable Underlying Objects. 32 Listing 3.12. Immutable Holder for Caching a Number and its Factors. 33 Listing 3.13. Caching the Last Result Using a Volatile Reference to an Immutable Holder Object. 33 Listing 3.14. Publishing an Object without Adequate Synchronization. Don't Do this. 33