Thread#alive?

() -> bool

thr.alive? → true or false

static VALUE
rb_thread_alive_p(VALUE thread)
{
    return RBOOL(!thread_finished(rb_thread_ptr(thread)));
}

Returns true if thr is running or sleeping.

Example

thr = Thread.new { }
thr.join                #=> #<Thread:0x401b3fb0 dead>
Thread.current.alive?   #=> true
thr.alive?              #=> false