Update threads.c to avoid a deadlock.

examples/threads.janet

@@ -1,10 +1,11 @@
 (defn worker-main
+  "Sends 11 messages back to parent"
   [parent]
   (def name (:receive parent))
   (def interval (:receive parent))
   (for i 0 10
     (os/sleep interval)
-    (printf "thread %s wakeup no. %d" name i))
+    (:send parent (string/format "thread %s wakeup no. %d" name i)))
   (:send parent name))
 
 (defn make-worker
@@ -14,10 +15,45 @@
       (:send name)
       (:send interval)))
 
-(def bob (make-worker "bob" 0.2))
-(def joe (make-worker "joe" 0.3))
-(def sam (make-worker "sam" 0.5))
+(def bob (make-worker "bob" 0.02))
+(def joe (make-worker "joe" 0.03))
+(def sam (make-worker "sam" 0.05))
+
+(:close joe)
+
+(try (:receive joe) ([err] (print "Got expected error: " err)))
 
 # Receive out of order
-(for i 0 3
-  (print "worker " (thread/receive [bob sam joe]) " finished!"))
+(for i 0 22
+  (print (thread/receive [bob sam])))
+
+#
+# Recursive Thread Tree - should pause for a bit, and then print a cool zigzag.
+#
+
+(def rng (math/rng (os/cryptorand 16)))
+
+(defn choose [& xs]
+  (in xs (:int rng (length xs))))
+
+(defn worker-tree
+  [parent]
+  (def name (:receive parent))
+  (def depth (:receive parent))
+  (if (< depth 5)
+    (do
+    (defn subtree []
+      (-> (thread/new)
+          (:send worker-tree)
+          (:send (string name "/" (choose "bob" "marley" "harry" "suki" "anna" "yu")))
+          (:send (inc depth))))
+    (let [l (subtree)
+          r (subtree)
+          lrep (thread/receive l)
+          rrep (thread/receive r)]
+      (:send parent [name ;lrep ;rrep])))
+    (do
+      (:send parent [name]))))
+
+(def lines (:receive (-> (thread/new) (:send worker-tree) (:send "adam") (:send 0))))
+(map print lines)