1 files changed, 139 insertions, 0 deletions
diff --git a/vespajlib/src/test/java/com/yahoo/concurrent/ExecutorsTestCase.java b/vespajlib/src/test/java/com/yahoo/concurrent/ExecutorsTestCase.java
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index 00000000000..b8f2b0e5c58
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+++ b/vespajlib/src/test/java/com/yahoo/concurrent/ExecutorsTestCase.java
@@ -0,0 +1,139 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.concurrent;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Ignore;
+import org.junit.Test;
+
+import java.util.LinkedList;
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class ExecutorsTestCase {
+    static private class Runner implements Runnable {
+        static private AtomicInteger threadCount = new AtomicInteger(0);
+        static private class ThreadId extends ThreadLocal<Integer> {
+            @Override
+            protected Integer initialValue() {
+                return new Integer(threadCount.getAndIncrement());
+            }
+        }
+        static private ThreadId threadId = new ThreadId();
+        private volatile int runBy = -1;
+        @Override
+        public void run() {
+            runBy = threadId.get();
+        }
+        int getRunBy() { return runBy; }
+    }
+
+    private static class Producer implements Runnable {
+        private volatile int maxThreadId = 0;
+        private final long timeOutMS;
+        private final ExecutorService consumer;
+        Producer(ExecutorService consumer, long timeOutMS) {
+            this.timeOutMS = timeOutMS;
+            this.consumer = consumer;
+        }
+        @Override
+        public void run() {
+            long now = System.currentTimeMillis();
+            Runner r = new Runner();
+            try {
+                while (now + timeOutMS > System.currentTimeMillis()) {
+                    Future<?> f = consumer.submit(r);
+                    f.get();
+                    maxThreadId = Math.max(maxThreadId, r.getRunBy());
+                    Thread.sleep(1);
+
+                }
+            } catch (InterruptedException e) {
+                assertTrue(false);
+            } catch (ExecutionException e) {
+                assertTrue(false);
+            }
+
+        }
+    }
+
+    private void assertThreadId(ExecutorService s, int id) throws InterruptedException, ExecutionException {
+        Runner r = new Runner();
+        Future<?> f = s.submit(r);
+        assertNull(f.get());
+        assertEquals(id, r.getRunBy());
+    }
+    private void assertRoundRobinOrder(ExecutorService s) throws InterruptedException, ExecutionException {
+        assertThreadId(s, 0);
+        assertThreadId(s, 1);
+        assertThreadId(s, 2);
+        assertThreadId(s, 0);
+        assertThreadId(s, 1);
+        assertThreadId(s, 2);
+        assertThreadId(s, 0);
+        assertThreadId(s, 1);
+    }
+    private int measureMaxNumThreadsUsage(ThreadPoolExecutor s, long durationMS, int maxProducers) throws InterruptedException, ExecutionException {
+        s.prestartAllCoreThreads();
+        ExecutorService consumers = Executors.newCachedThreadPool();
+        LinkedList<Future<Producer>> futures = new LinkedList<>();
+        for (int i = 0; i < maxProducers; i++) {
+            Producer p = new Producer(s, durationMS);
+            futures.add(consumers.submit(p, p));
+        }
+        int maxThreadId = 0;
+        try {
+            while (! futures.isEmpty()) {
+                Producer p = futures.remove().get();
+                maxThreadId = Math.max(maxThreadId, p.maxThreadId);
+            }
+        } catch (InterruptedException e) {
+            assertTrue(false);
+        } catch (ExecutionException e) {
+            assertTrue(false);
+        }
+        return maxThreadId;
+    }
+    private void assertStackOrder(ThreadPoolExecutor s) throws InterruptedException, ExecutionException {
+        s.prestartAllCoreThreads();
+        Thread.sleep(10);           //Sleep to allow last executing thread to get back on the stack
+        assertThreadId(s, 0);
+        Thread.sleep(10);
+        assertThreadId(s, 0);
+        Thread.sleep(10);
+        assertThreadId(s, 0);
+        Thread.sleep(10);
+        assertThreadId(s, 0);
+        Thread.sleep(10);
+        assertThreadId(s, 0);
+        Thread.sleep(10);
+        assertThreadId(s, 0);
+        Thread.sleep(10);
+        assertThreadId(s, 0);
+    }
+    
+    @Ignore // Ignored as it is not deterministic, and probably hard to make deterministic to.
+    @Test
+    public void requireThatExecutionOrderIsPredictable() throws InterruptedException, ExecutionException {
+        Runner.threadCount.set(0);
+        assertRoundRobinOrder(new ThreadPoolExecutor(3, 3, 0L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()));
+        Runner.threadCount.set(0);
+        assertRoundRobinOrder(new ThreadPoolExecutor(3, 3, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(true)));
+        Runner.threadCount.set(0);
+        assertStackOrder(new ThreadPoolExecutor(3, 3, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(false)));
+    }
+    
+    @Ignore // Ignored as it might not be deterministic
+    public void requireThatExecutionOrderIsPredictableUnderLoad() throws InterruptedException, ExecutionException {
+        Runner.threadCount.set(0);
+        assertEquals(99, measureMaxNumThreadsUsage(new ThreadPoolExecutor(100, 100, 0L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()), 3000, 10));
+        Runner.threadCount.set(0);
+        assertEquals(99, measureMaxNumThreadsUsage(new ThreadPoolExecutor(100, 100, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(true)), 3000, 10));
+        Runner.threadCount.set(0);
+        //Max 9 concurrent tasks. Might not be deterministic
+        assertEquals(9, measureMaxNumThreadsUsage(new ThreadPoolExecutor(100, 100, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(false)), 3000, 10));
+        Runner.threadCount.set(0);
+    }
+}