I have some code that dynamically allocates a new std::thread from the C++11 <thread> header, like this:
std::thread *th = new thread( /* my args */);
Some time later, I call join:
th->join();
Since I dynamically allocated the thread, do I also need to call delete th; to free the memory? If I do, do I still need to call join() first?
To avoid memory leaks, you need to both: join a running thread, and make sure it is destructed/deleted (let it go out of scope for stack-allocated std::threads or explicitly call delete for std::thread*).
See thread::~thread in cppreference:
A thread object does not have an associated thread (and is safe to destroy) after:
- it was default-constructed
- it was moved from
- join() has been called
- detach() has been called
A non-joined thread, therefore, cannot be safely destructed.
A join()ed std::thread will still occupy some memory. Therefore you need to make sure it is properly deallocated if it is on the heap.