Thread.current

static VALUE
thread_s_current(VALUE klass)
{
    return rb_thread_current();
}

Thread.current   #=> #<Thread:0x401bdf4c run>

See also .abort_on_exception= .each_caller_location .abort_on_exception .exit also in 4.1 · 4.0 · 3.4 · 3.2 · 3.1 · 3.0