[Boost-bugs] [Boost C++ Libraries] #8600: wait_for_any hangs, if called with multiple copies of shared_future referencing same task

Subject: [Boost-bugs] [Boost C++ Libraries] #8600: wait_for_any hangs, if called with multiple copies of shared_future referencing same task
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-05-21 11:50:16

#8600: wait_for_any hangs, if called with multiple copies of shared_future
referencing same task
--------------------------------------------------+-------------------------
 Reporter:  Martin Apel <martin.apel@…>           |       Owner:  anthonyw
     Type:  Bugs                                  |      Status:  new     
Milestone:  To Be Determined                      |   Component:  thread  
  Version:  Boost 1.53.0                          |    Severity:  Problem 
 Keywords:                                        |  
--------------------------------------------------+-------------------------
 The following small test program shows the problem:

 {{{
 #include <iostream>
 #include <boost/thread.hpp>

 int calculate_the_answer_to_life_the_universe_and_everything()
 {
     return 42;
 }

 int main(int argc, char* argv[])
 {
    boost::packaged_task<int>
 pt(calculate_the_answer_to_life_the_universe_and_everything);
    boost::shared_future<int> fi1 =
 boost::shared_future<int>(pt.get_future());
    boost::shared_future<int> fi2 = fi1;

    boost::thread task(boost::move(pt)); // launch task on a thread

    boost::wait_for_any(fi1, fi2);
    std::cout << "Wait for any returned\n";
    return (0);
 }
 }}}

 This program hangs infinitely in the call to boost::wait_for_any. From the
 docs I would expect this to work, because it's allowed to copy
 shared_futures. If this is not allowed, a possibility would be needed, to
 find out, if two shared_futures point to the same task or not. Currently
 wait_for_any is unusable, if there are chances, that multiple
 shared_futures point to the same result.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/8600>
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