Is Meyers’ implementation of the Singleton pattern thread safe?

by

In C++11, it is thread safe. According to the standard, §6.7 [stmt.dcl] p4:

If control enters
the declaration concurrently while the variable is being initialized, the concurrent execution shall wait for completion of the initialization.

GCC and VS support for the feature (Dynamic Initialization and Destruction with Concurrency, also known as Magic Statics on MSDN) is as follows:

Thanks to @Mankarse and @olen_gam for their comments.

In C++03, this code wasn’t thread safe. There is an article by Meyers called “C++ and the Perils of Double-Checked Locking” which discusses thread safe implementations of the pattern, and the conclusion is, more or less, that (in C++03) full locking around the instantiating method is basically the simplest way to ensure proper concurrency on all platforms, while most forms of double-checked locking pattern variants may suffer from race conditions on certain architectures, unless instructions are interleaved with strategically places memory barriers.

More Related Contents:

  1. Difference between list<Observer*>* and list<Observer*> in C++ [closed]
  2. How to implement the factory method pattern in C++ correctly
  3. What happens to a detached thread when main() exits?
  4. Thread pooling in C++11
  5. Reducing on array in OpenMP
  6. How to execute a functor or a lambda in a given thread in Qt, GCD-style?
  7. Do I have to acquire lock before calling condition_variable.notify_one()?
  8. Does MinGW-w64 support std::thread out of the box when using the Win32 threading model?
  9. Is it safe to fork from within a thread?
  10. Does the C++ volatile keyword introduce a memory fence?
  11. OpenMP set_num_threads() is not working
  12. How can I use something like std::vector?
  13. Circular lock-free buffer
  14. Thread safe implementation of circular buffer
  15. Can I force cache coherency on a multicore x86 CPU?
  16. Practical Uses for the “Curiously Recurring Template Pattern”
  17. Thread safety of std::map for read-only operations
  18. boost thread throwing exception “thread_resource_error: resource temporarily unavailable”
  19. Reusing thread in loop c++
  20. How to automatically register a class on creation
  21. c++, std::atomic, what is std::memory_order and how to use them?
  22. C++ Thread Pool [closed]
  23. OpenMP: What is the benefit of nesting parallelizations?
  24. Is MAXIMUM_WAIT_OBJECTS really 64?
  25. How to implement a unmanaged thread-safe collection when I get this error: is not supported when compiling with /clr
  26. Portable Compare And Swap (atomic operations) C/C++ library?
  27. Is it possible to use threads to speed up file reading?
  28. signal handler function in multithreaded environment
  29. Decorator pattern in C++
  30. Loading a dll from a dll?

Leave a Comment