CODEWITHSUNDEEP
multithreadingc++11g++
zoska
zoska

Reputation: 1723

Destructor of a joinable std::thread

The specification (? - got it from cppreference) states:

~thread(); (since C++11)

Destroys the thread object. If *this still has an associated running thread (i.e. joinable() == true), std::terminate() is called.

I've checked that calling std::terminate() inside thread aborts the whole program.

So to check destructor behaviour I wrote this code:

#include <iostream>
#include <thread>
#include <memory>

int main() {
    std::unique_ptr<std::thread> thread_ptr(new std::thread([](){
            std::cout << "Starting thread: " << std::endl;
            while(1) {}
            }));
    while(!thread_ptr->joinable()){}
    std::cout << thread_ptr->joinable() << std::endl;
    thread_ptr.release();
    std::cout << "Main is still alive!" << std::endl;
    return 0; 
}

Expecting abort of whole process.

No such thing happened, all output was a permutation of messages, like:

1Starting thread:

Main is still alive!

I'm using g++ : Thread model: posix, gcc version 4.8.1 (Ubuntu 4.8.1-2ubuntu1~12.04)

Do I have wrong understanding of specification? Wrong code? Or g++ isn't just compliant with this specification?

Upvotes: 4

Views: 412

Answers (1)

Angew is no longer proud of SO
Angew is no longer proud of SO

Reputation: 171097

You probably meant thread_ptr.reset() instead of thread_ptr.release(). release() relinquishes ownership of the pointer, i.e. you leak the std::thread instance and its destructor is thus never called.

Upvotes: 2

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