8069291: [TESTBUG] runtime/threads/Fibonacci: OutOfMemoryError: unable to create native thread

Reviewed-by: dholmes, ctornqvi

hotspot/test/runtime/Thread/Fibonacci.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @summary Calculates Fibonacci numbers "recursively" via threads and compares
+ *     the result with the classical calculation.
+ *     This test is skipped on 32-bit Windows: limited virtual space on Win-32
+ *     make this test inherently unstable on Windows with 32-bit VM data model.
+ * @requires !(os.family == "windows" & sun.arch.data.model == "32")
+ * @library /testlibrary
+ * @run main Fibonacci 15
+ */
+
+import com.oracle.java.testlibrary.Asserts;
+
+public class Fibonacci extends Thread {
+    private int index;
+    private int value;
+    private Fibonacci left;
+    private Fibonacci right;
+
+    public Fibonacci(int i) {
+        index = i;
+    }
+
+    private int getValue() {
+        return value;
+    }
+
+    @Override
+    public void run() {
+        if (index == 0 || index == 1) {
+            // base cases, 0 Fibonacci number = 0, 1 Fibonacci number = 1
+            value = index;
+        } else {
+            // inductive cases
+            left = new Fibonacci(index - 2);
+            right = new Fibonacci(index - 1);
+            left.start();
+            right.start();
+            try {
+                left.join();
+                right.join();
+            } catch (InterruptedException e) {
+                throw new Error("InterruptedException for index " + index, e);
+            }
+            // compute and terminate
+            value = left.getValue() + right.getValue();
+        }
+    }
+
+    public static int traditionalFibonacci(int n) {
+        int n1 = 0, n2 = 1, nn = 0;
+
+        if (n == 0 || n == 1) {
+           nn = n;
+        }
+
+        for (int i = 1; i < n; ++i) {
+            nn = n2 + n1;
+            n1 = n2;
+            n2 = nn;
+        }
+        return nn;
+    }
+
+    public static void main(String[] args) throws Error,AssertionError {
+        int expected;
+        int number;
+        Fibonacci recursiveFibonacci;
+
+        if (args.length != 1) {
+            throw new Error("Error: args.length must be 1");
+        }
+
+        number = Integer.parseInt(args[0]);
+        recursiveFibonacci = new Fibonacci(number);
+
+        recursiveFibonacci.start();
+        try {
+            recursiveFibonacci.join();
+        } catch (InterruptedException e) {
+            throw new Error("InterruptedException in main thread", e);
+        }
+
+        expected = traditionalFibonacci(number);
+
+        System.out.println("Fibonacci[" + number + "] = " + expected);
+
+        Asserts.assertEQ(recursiveFibonacci.getValue(), expected,
+                          "Unexpected calculated value: " + recursiveFibonacci.getValue() + " expected " + expected );
+    }
+}