--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/demo/jvmti/Context.java Wed Jul 15 13:21:25 2015 +0200
@@ -0,0 +1,188 @@
+/*
+ * Copyright (c) 2004, 2014, 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.
+ */
+
+
+/*
+ *
+ * Sample target application for jvmti demos
+ *
+ * java Context [threadCount [iterationCount [sleepContention]]]
+ * Default: java Context 5 10 0
+ *
+ * threadCount Number of threads
+ * iterationCount Total turns taken for all threads
+ * sleepContention Time for main thread to sleep while holding lock
+ * (creates monitor contention on all other threads)
+ *
+ */
+
+/* Used to sync up turns and keep track of who's turn it is */
+final class TurnChecker {
+ int thread_index;
+ TurnChecker(int thread_index) {
+ this.thread_index = thread_index;
+ }
+}
+
+/* Creates a bunch of threads that sequentially take turns */
+public final class Context extends Thread {
+ /* Used to track threads */
+ private static long startTime;
+ private static TurnChecker turn = new TurnChecker(-1);
+ private static int total_turns_taken;
+
+ /* Used for each Context thread */
+ private final int thread_count;
+ private final int thread_index;
+ private final int thread_turns;
+
+ /* Main program */
+ public static void main(String[] argv) throws InterruptedException {
+ int default_thread_count = 5;
+ int default_thread_turns = 10;
+ int default_contention_sleep = 0;
+ int expected_turns_taken;
+ long sleepTime = 10L;
+
+ /* Override defaults */
+ if ( argv.length >= 1 ) {
+ default_thread_count = Integer.parseInt(argv[0]);
+ }
+ if ( argv.length >= 2 ) {
+ expected_turns_taken = Integer.parseInt(argv[1]);
+ default_thread_turns = expected_turns_taken/default_thread_count;
+ }
+ expected_turns_taken = default_thread_count*default_thread_turns;
+ if ( argv.length >= 3 ) {
+ default_contention_sleep = Integer.parseInt(argv[2]);
+ }
+
+ System.out.println("Context started with "
+ + default_thread_count + " threads and "
+ + default_thread_turns + " turns per thread");
+
+ /* Get all threads running (they will block until we set turn) */
+ for (int i = 0; i < default_thread_count; i++) {
+ new Context(default_thread_count, i, default_thread_turns).start();
+ }
+
+ /* Sleep to make sure thread_index 0 make it to the wait call */
+ System.out.println("Context sleeping, so threads will start wait");
+ Thread.yield();
+ Thread.sleep(sleepTime);
+
+ /* Save start time */
+ startTime = System.currentTimeMillis();
+
+ /* This triggers the starting of taking turns */
+ synchronized (turn) {
+ turn.thread_index = 0;
+ turn.notifyAll();
+ }
+ System.out.println("Context sleeping, so threads can run");
+ Thread.yield();
+ Thread.sleep(sleepTime);
+
+ /* Wait for threads to finish (after everyone has had their turns) */
+ while ( true ) {
+ boolean done;
+ done = false;
+ synchronized (turn) {
+ if ( total_turns_taken == expected_turns_taken ) {
+ done = true;
+ }
+ /* Create some monitor contention by sleeping with lock */
+ if ( default_contention_sleep > 0 ) {
+ System.out.println("Context sleeping, to create contention");
+ Thread.yield();
+ Thread.sleep((long)default_contention_sleep);
+ }
+ }
+ if ( done )
+ break;
+ System.out.println("Context sleeping, so threads will complete");
+ Thread.sleep(sleepTime);
+ }
+
+ long endTime = System.currentTimeMillis();
+ long totalTime = endTime - startTime;
+
+ System.out.println("Total time (milliseconds): " + totalTime);
+ System.out.println("Milliseconds per thread: " +
+ ((double)totalTime / (default_thread_count)));
+
+ System.out.println("Context completed");
+ System.exit(0);
+ }
+
+ /* Thread object to run */
+ Context(int thread_count, int thread_index, int thread_turns) {
+ this.thread_count = thread_count;
+ this.thread_index = thread_index;
+ this.thread_turns = thread_turns;
+ }
+
+ /* Main for thread */
+ public void run() {
+ int next_thread_index = (thread_index + 1) % thread_count;
+ int turns_taken = 0;
+
+ try {
+
+ /* Loop until we make sure we get all our turns */
+ for (int i = 0; i < thread_turns * thread_count; i++) {
+ synchronized (turn) {
+ /* Keep waiting for our turn */
+ while (turn.thread_index != thread_index)
+ turn.wait();
+ /* MY TURN! Each thread gets thread_turns */
+ total_turns_taken++;
+ turns_taken++;
+ System.out.println("Turn #" + total_turns_taken
+ + " taken by thread " + thread_index
+ + ", " + turns_taken
+ + " turns taken by this thread");
+ /* Give next thread a turn */
+ turn.thread_index = next_thread_index;
+ turn.notifyAll();
+ }
+ /* If we've had all our turns, break out of this loop */
+ if (thread_turns == turns_taken) {
+ System.out.println("Loop end: thread got " + turns_taken
+ + " turns, expected " + thread_turns);
+ break;
+ }
+ }
+ } catch (InterruptedException intEx) {
+ System.out.println("Got an InterruptedException:" + intEx);
+ /* skip */
+ }
+
+ /* Make sure we got all our turns */
+ if ( thread_turns != turns_taken ) {
+ System.out.println("ERROR: thread got " + turns_taken
+ + " turns, expected " + thread_turns);
+ System.exit(1);
+ }
+ }
+}