diff --git a/src/rt/runtime.rs b/src/rt/runtime.rs
index 9227d249..efdc314b 100644
--- a/src/rt/runtime.rs
+++ b/src/rt/runtime.rs
@@ -122,11 +122,12 @@ impl Runtime {
                 // Get a list of new machines to start, if any need to be started.
                 let machines = self.make_machines();
                 for m in machines {
+                    // println!("{} -- looking for thread", k);
                     idle = 0;
 
                     // println!("getting idle thread");
-                    let mut sched = self.sched.lock().unwrap();
-                    'inner: for thread in &sched.threads {
+                    let sched = self.sched.lock().unwrap();
+                    'inner: for (i, thread) in sched.threads.iter().enumerate() {
                         // grab the first parked thread
                         if thread
                             .parked
@@ -135,18 +136,22 @@ impl Runtime {
                             // transfer the machine
                             thread
                                 .machine_sender
-                                .send(m)
+                                .send(m.clone())
                                 .expect("failed to send machine to thread");
                             // unpark the thread
                             thread.unparker.unpark();
+                            // println!("{} found thread to unpark {}", k, i);
                             break 'inner;
                         }
                     }
-
+                    let len = sched.threads.len();
+                    drop(sched);
                     // no idle thread available, check if we can spawn one
-                    if sched.threads.len() < *MAXPROCS {
+                    if len < *MAXPROCS {
+                        let i = len;
+                        // println!("{} spawning thread {}", k, i);
                         // we can spawn one, lets do it
-                        let parked = Arc::new(atomic::AtomicBool::new(true));
+                        let parked = Arc::new(atomic::AtomicBool::new(false));
                         let parked2 = parked.clone();
                         let (machine_sender, machine_recv) = crossbeam_channel::bounded(1);
                         let parker = Parker::new();
@@ -159,7 +164,9 @@ impl Runtime {
                                     loop {
                                         while parked2.load(Ordering::Acquire) {
                                             parker.park();
+                                            // TODO: shutdown if idle for too long
                                         }
+                                        // println!("{} thread unparked {}", k, i);
                                         // when this thread is unparked, retrieve machine
                                         let m: Arc<Machine> =
                                             machine_recv.recv().expect("failed to receive machine");
@@ -169,18 +176,28 @@ impl Runtime {
                                         m.run(self);
                                         // when run ends, go into parked mode again
                                         parked2.store(false, Ordering::Relaxed);
+                                        // println!("thread parked {}", i);
                                     }
                                 })
                             })
                             .expect("cannot start a machine thread");
 
+                        let mut sched = self.sched.lock().unwrap();
+
+                        // transfer the machine
+                        machine_sender
+                            .send(m)
+                            .expect("failed to send machine to thread");
+
+                        // println!("started thread {}", i);
+
                         sched.threads.push(ThreadState {
                             unparker,
                             parked,
                             machine_sender,
                         });
+                        drop(sched);
                     }
-                    drop(sched);
                 }
 
                 // Sleep for a bit longer if the scheduler state hasn't changed in a while.
@@ -209,7 +226,6 @@ impl Runtime {
                 let m = Arc::new(Machine::new(p));
                 to_start.push(m.clone());
                 sched.machines.push(m);
-                assert!(sched.machines.len() <= *MAXPROCS);
             }
         }
 
@@ -417,11 +433,7 @@ impl Machine {
             // println!("returning processor to pool");
             let mut sched = rt.sched.lock().unwrap();
             sched.processors.push(p);
-            assert!(sched.processors.len() <= *MAXPROCS);
-            // println!("machines {}", sched.machines.len());
             sched.machines.retain(|elem| !ptr::eq(&**elem, self));
-            // println!("machines retained {}", sched.machines.len());
-            assert!(sched.machines.len() <= *MAXPROCS);
         }
     }
 }