Semaphore example

winterbe · winterbe · commit bbf062daea32 · 2015-04-22T07:49:05.000+02:00
diff --git a/src/com/winterbe/java8/samples/concurrent/Semaphore2.java b/src/com/winterbe/java8/samples/concurrent/Semaphore2.java
@@ -0,0 +1,44 @@
+package com.winterbe.java8.samples.concurrent;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+/**
+ * @author Benjamin Winterberg
+ */
+public class Semaphore2 {
+
+    private static Semaphore semaphore = new Semaphore(5);
+
+    public static void main(String[] args) {
+        ExecutorService executor = Executors.newFixedThreadPool(10);
+
+        IntStream.range(0, 10)
+                .forEach(i -> executor.submit(Semaphore2::doWork));
+
+        ConcurrentUtils.stop(executor);
+    }
+
+    private static void doWork() {
+        boolean permit = false;
+        try {
+            permit = semaphore.tryAcquire(1, TimeUnit.SECONDS);
+            if (permit) {
+                System.out.println("Semaphore acquired");
+                ConcurrentUtils.sleep(5);
+            } else {
+                System.out.println("Could not acquire semaphore");
+            }
+        } catch (InterruptedException e) {
+            throw new IllegalStateException(e);
+        } finally {
+            if (permit) {
+                semaphore.release();
+            }
+        }
+    }
+
+}
