Is it safe to re-assign detached boost::thread

Question

For example

boost::thread th = boost::thread(a_lengthy_function);
th.detach();
th = boost::thread(another_function);

Will first thread be canceled or affected by second thread?

Consider what detaching a thread does. It'd be really idiosyncratic if the handles still affected a detached thread in some way. — StoryTeller - Unslander Monica, Nov 23 '17 at 10:14

score 4 · Accepted Answer · edited Jun 20 '20 at 09:12

from boost doc:

A thread can be detached by explicitly invoking the detach() member function on the boost::thread object. In this case, the boost::thread object ceases to represent the now-detached thread, and instead represents Not-a-Thread.

thread() noexcept;Effects:Constructs a boost::thread instance that refers to Not-a-Thread

so a detached thread is the same thing as a default constructed thread. So, yes, you can safely move-assign to a default constructed thread, and the answer to your second question is no, the two threads are totally unrelated.

FYI, the same applies to std::thread as well ...

score 0 · Answer 2 · answered Nov 23 '17 at 10:14

This shouldn't matter at all.

As mentioned by André Caron:

The boost::thread object's lifetime and the native thread's lifetime are unrelated. The boost::thread object can go out of scope at any time.

from What’s the best way to delete boost::thread object right after its work is complete?

Is it safe to re-assign detached boost::thread

2 Answers2