如何使用 c++ boost::interprocess 库通过命名共享 memory 与 Python 通信？

Question

Purpose: Let c++ process communicate with python process on this computer, and intend to use shared memory to communicate. C++ uses the boost::interprocess library to create a named shared memory through shared_memory_object, and writes data into it, while python reads the corresponding data.

Question: how does python access data based on the name of the corresponding shared memory in c++?

Here's the clip I wrote:

          struct test_datas {
            char name[128];
            char sender[128];
            union u_data {
                char s1_[1024];
                long l1_;
                double d_;
            } u_member;
        };
        
        void write_shared_memory() {
            using namespace boost::interprocess;
            shared_memory_object shdmem(open_or_create , "monika", read_write);
            shdmem.truncate(sizeof(test_datas));
            mapped_region region(shdmem , read_write);
        
            auto *data_ptr = static_cast<test_datas *>(region.get_address());
            sprintf(data_ptr->name , "%s" , "named");
            sprintf(data_ptr->sender , "%s" , "myself");
            data_ptr->u_member.d_ = 66.890;
    }

Here is the corresponding Python code:

    from multiprocessing import shared_memory
    
    if __name__ == "__main__":
        shm_a = shared_memory.SharedMemory(name="monika", create=False)
        buffer = shm_a.buf
        print(buffer[0])

---

    error: FileNotFoundError: [WinError 2] The system cannot find the file specified: 'monika'

Answer 1

Assuming POSIX (eg Linux) here, both create SHM "files", so on say Ubuntu /dev/shm/monika.

However, it seems that Python by default attempts to clean it up. See docs :

When one process no longer needs access to a shared memory block that might still be needed by other processes, the close() method should be called.

However, this suggests that the Python shared memory facility is much less general purpose than usual, see eg Shared memory deleted at exit