Is it smart to replace boost::thread and boost::mutex with c++11 equivalents?

NoSenseEtAl picture NoSenseEtAl · Aug 30, 2011 · Viewed 41.5k times · Source

Motivation: reason why I'm considering it is that my genius project manager thinks that boost is another dependency and that it is horrible because "you depend on it"(I tried explaining the quality of boost, then gave up after some time :( ). Smaller reason why I would like to do it is that I would like to learn c++11 features, because people will start writing code in it. So:

  1. Is there a 1:1 mapping between #include<thread> #include<mutex>and boost equivalents?
  2. Would you consider a good idea to replace boost stuff with c++11
    stuff. My usage is primitive, but are there examples when std doesnt offer what boost does? Or (blasphemy) vice versa?

P.S. I use GCC so headers are there.

Answer

Anthony Williams picture Anthony Williams · Aug 30, 2011

There are several differences between Boost.Thread and the C++11 standard thread library:

  • Boost supports thread cancellation, C++11 threads do not
  • C++11 supports std::async, but Boost does not
  • Boost has a boost::shared_mutex for multiple-reader/single-writer locking. The analogous std::shared_timed_mutex is available only since C++14 (N3891), while std::shared_mutex is available only since C++17 (N4508).
  • C++11 timeouts are different to Boost timeouts (though this should soon change now Boost.Chrono has been accepted).
  • Some of the names are different (e.g. boost::unique_future vs std::future)
  • The argument-passing semantics of std::thread are different to boost::thread --- Boost uses boost::bind, which requires copyable arguments. std::thread allows move-only types such as std::unique_ptr to be passed as arguments. Due to the use of boost::bind, the semantics of placeholders such as _1 in nested bind expressions can be different too.
  • If you don't explicitly call join() or detach() then the boost::thread destructor and assignment operator will call detach() on the thread object being destroyed/assigned to. With a C++11 std::thread object, this will result in a call to std::terminate() and abort the application.

To clarify the point about move-only parameters, the following is valid C++11, and transfers the ownership of the int from the temporary std::unique_ptr to the parameter of f1 when the new thread is started. However, if you use boost::thread then it won't work, as it uses boost::bind internally, and std::unique_ptr cannot be copied. There is also a bug in the C++11 thread library provided with GCC that prevents this working, as it uses std::bind in the implementation there too.

void f1(std::unique_ptr<int>);
std::thread t1(f1,std::unique_ptr<int>(new int(42)));

If you are using Boost then you can probably switch to C++11 threads relatively painlessly if your compiler supports it (e.g. recent versions of GCC on linux have a mostly-complete implementation of the C++11 thread library available in -std=c++0x mode).

If your compiler doesn't support C++11 threads then you may be able to get a third-party implementation such as Just::Thread, but this is still a dependency.