Mac OS X：升级进程间信号量timed_wait：异常CPU消耗

Question

将代码段从Windows移植到Mac OS X后，我发现它在运行时会占用整个CPU内核;负责调用CPU消耗的是boost :: interprocess :: interprocess_semaphore :: timed_wait。

下面是重现此行为的代码部分。

#include <boost/interprocess/sync/interprocess_semaphore.hpp> 
#include <boost/interprocess/shared_memory_object.hpp> 
#include <boost/interprocess/mapped_region.hpp> 

#include <boost/thread/thread_time.hpp> 

#include <iostream> 

static bool gStopRequested(false); 

struct ShmObj 
{ 
    boost::interprocess::interprocess_semaphore mSemaphore; 
    ShmObj() : mSemaphore(0) {}; 
    ~ShmObj() {}; 
}; 

int main(char* argc, const char** argv) 
{ 
    boost::interprocess::shared_memory_object* lShmObj = NULL; 
    std::string lShmObjName("My_Boost_Interprocess_Test"); 
    boost::interprocess::mapped_region* lRegion; 
    ShmObj* lObj; 

    //Create shared segment 
    try 
    { 
     lShmObj = new boost::interprocess::shared_memory_object(boost::interprocess::create_only, lShmObjName.c_str(), boost::interprocess::read_write); 
    } 
    catch (boost::interprocess::interprocess_exception &ex) 
    { 
     if (ex.get_error_code() != boost::interprocess::already_exists_error) 
     { 
      std::cerr << "Some error" << std::endl; 
      exit(1); 
     } 
     else 
     { 
      std::cerr << "Already exists, just taking it back." << std::endl; 
      try 
      { 
       lShmObj = new boost::interprocess::shared_memory_object(boost::interprocess::open_only, lShmObjName.c_str(), boost::interprocess::read_write); 
      } 
      catch (boost::interprocess::interprocess_exception &ex2) 
      { 
       std::cerr << "D'oh !" << std::endl; 
       exit(1); 
      } 
     } 
    } 
    if (!lShmObj) 
    { 
     exit(1); 
    } 
    lShmObj->truncate(sizeof(ShmObj)); 
    lRegion = new boost::interprocess::mapped_region(*lShmObj, boost::interprocess::read_write); 
    lObj = new (lRegion->get_address()) ShmObj; 

    // The loop 
    while (!gStopRequested) 
    { 
     boost::system_time lDeadlineAbsoluteTime = boost::get_system_time() + boost::posix_time::milliseconds(500); 

     if (lObj->mSemaphore.timed_wait(lDeadlineAbsoluteTime)) 
     { 
      std::cout << "acquired !" << std::endl; 
     } 
     else 
     { 
      std::cout << "tick" << std::endl; 
     } 
    } 
} 

然后，我读了无名信号量没有在Mac OS X中可用的，所以我认为这可能是因为未命名的信号量并没有有效地模拟......然后我尝试了以下，unsucessfully：

#include <boost/interprocess/sync/named_semaphore.hpp> 
#include <boost/thread/thread_time.hpp> 

#include <iostream> 

static bool gStopRequested(false); 

int main(char* argc, const char** argv) 
{ 
    boost::interprocess::named_semaphore::remove("My_Boost_Interprocess_Test"); 
    boost::interprocess::named_semaphore lMySemaphore(boost::interprocess::open_or_create, "My_Boost_Interprocess_Test", 1); 

    // The loop 
    while (!gStopRequested) 
    { 
     boost::system_time lDeadlineAbsoluteTime = boost::get_system_time() + boost::posix_time::milliseconds(500); 

     if (lMySemaphore.timed_wait(lDeadlineAbsoluteTime)) 
     { 
      std::cout << "acquired !" << std::endl; 
     } 
     else 
     { 
      std::cout << "tick" << std::endl; 
     } 
    } 
} 

由于可用的Posix原语，我实际上期待在Mac OS X上有一个更好的boost :: interprocess行为，但实际上并非如此。任何想法的决议？非常感谢。

Answer 1

我成功地用马赫的信号量，而不是提升间的::的那些...看http://pkaudio.blogspot.com/2010/05/mac-os-x-no-timed-semaphore-waits.html