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+#
+# The Dining Philosophers - thread example
+#
+require "thread"
+
+srand
+#srand
+N=9 # number of philosophers
+$forks = []
+for i in 0..N-1
+ $forks[i] = Mutex.new
+end
+$state = "-o"*N
+
+def wait
+ sleep rand(20)/10.0
+end
+
+def think(n)
+ wait
+end
+
+def eat(n)
+ wait
+end
+
+def philosopher(n)
+ while TRUE
+ think n
+ $forks[n].lock
+ if not $forks[(n+1)%N].try_lock
+ $forks[n].unlock # avoid deadlock
+ continue
+ end
+ $state[n*2] = ?|;
+ $state[(n+1)%N*2] = ?|;
+ $state[n*2+1] = ?*;
+ print $state, "\n"
+ eat(n)
+ $state[n*2] = ?-;
+ $state[(n+1)%N*2] = ?-;
+ $state[n*2+1] = ?o;
+ print $state, "\n"
+ $forks[n].unlock
+ $forks[(n+1)%N].unlock
+ end
+end
+
+for i in 0..N-1
+ Thread.start{philosopher(i)}
+ sleep 0.1
+end
+
+sleep