Function stream_watcher_spawn 

pub(crate) fn stream_watcher_spawn(obj: &Object) -> Result<Daemon>

Forward the BPF stdout/stderr streams of every program in the object to the scheduler’s stdout and stderr. Nothing reads these streams otherwise, so messages would be silently dropped. On a kernel with stream descriptors the watcher poll(2)s them and forwards each line as it is written. Elsewhere it reads the streams periodically. Called from ArenaLib::setup(), the watcher is owned by the returned ArenaLib.