The Double-Checked Locking Pattern is a common approach to efficient lazy initialization. Unfortunately, it’s not reliable in threaded systems, it can fail for different reasons in uniprocessor and multiprocessor environments, and there’s no portable way to make it reliable. Every C++ programmer needs to understand why this is the case, because it affects the very core of software development: code generation and program execution. This presentation takes a deep look at code generation, compiler and hardware optimization, sequence points, “observable behavior,” the significance of “volatile,” cache coherency problems, and memory barriers. It concludes with suggestions for those who want the efficiency of lazy initialization, but who value correct program behavior even more.
Scott Meyers is one of the world’s foremost experts on C++ software development. He wrote the best-selling Effective C++ series (Effective C++, More Effective C++, and Effective STL); wrote and designed the innovative Effective C++ CD; is consulting editor for Addison Wesley’s Effective Software Development Series; and is a member of the advisory board for Software Development magazine. He also sits on technical advisory boards for several start-up companies. A programmer since 1972, he holds an M.S. in Computer Science from Stanford University and a Ph.D. from Brown University.
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