warn on Singlethread executor

Author: Baunsgaard

src/main/java/org/apache/sysds/runtime/util/CommonThreadPool.java

@@ -105,42 +105,42 @@ public static ExecutorService get() {
 	 * @return The executor with specified parallelism
 	 */
 	public synchronized static ExecutorService get(int k) {
-		// if(k <= 1){
-			// LOG.error("Invalid to create thread pool with <= one thread returning single thread executor", new RuntimeException());
+		if(k <= 1){
+			LOG.warn("Invalid to create thread pool with <= one thread returning single thread executor", new RuntimeException());
 			return new SameThreadExecutorService();
-		// }
-
-		// final Thread thisThread = Thread.currentThread();
-		// final String threadName = thisThread.getName();
-		// // Contains main, because we name our test threads TestRunner_main
-		// final boolean mainThread = threadName.contains("main");
-		// if(size == k && mainThread)
-		// 	return shared; // use the default thread pool if main thread and max parallelism.
-		// else if(mainThread || threadName.contains("PARFOR")) {
-		// 	CommonThreadPool pool;
-		// 	if(shared2 == null) // If there is no current shared pool allocate one.
-		// 		shared2 = new ConcurrentHashMap<>();
-
-		// 	pool = shared2.get(thisThread.getId());
-		// 	if(pool == null) { // If there is no pool for this thread allocate one.
-		// 		pool = new CommonThreadPool(new ForkJoinPool(k));
-		// 		shared2.put(thisThread.getId(), pool);
-		// 	}
-
-		// 	return pool; // Return the shared pool for this parfor or main thread.
-		// }
-		// else {
-		// 	// If we are neither a main thread or parfor thread, allocate a new thread pool
-		// 	if(!incorrectPoolUse){
-		// 		LOG.warn("An instruction allocated it's own thread pool indicating that some task is not properly reusing the threads.");
+		}
+
+		final Thread thisThread = Thread.currentThread();
+		final String threadName = thisThread.getName();
+		// Contains main, because we name our test threads TestRunner_main
+		final boolean mainThread = threadName.contains("main");
+		if(size == k && mainThread)
+			return shared; // use the default thread pool if main thread and max parallelism.
+		else if(mainThread || threadName.contains("PARFOR")) {
+			CommonThreadPool pool;
+			if(shared2 == null) // If there is no current shared pool allocate one.
+				shared2 = new ConcurrentHashMap<>();
+
+			pool = shared2.get(thisThread.getId());
+			if(pool == null) { // If there is no pool for this thread allocate one.
+				pool = new CommonThreadPool(new ForkJoinPool(k));
+				shared2.put(thisThread.getId(), pool);
+			}
+
+			return pool; // Return the shared pool for this parfor or main thread.
+		}
+		else {
+			// If we are neither a main thread or parfor thread, allocate a new thread pool
+			if(!incorrectPoolUse){
+				LOG.warn("An instruction allocated it's own thread pool indicating that some task is not properly reusing the threads.");
 
-		// 		if(threadName.contains("test"))
-		// 			LOG.error("Thread from test is not correctly using pools, please modify thread name to contain 'main'");
-		// 		incorrectPoolUse = true;
-		// 		return new CommonThreadPool(new ForkJoinPool(k));
-		// 	}
-		// 	return Executors.newFixedThreadPool(k);
-		// }
+				if(threadName.contains("test"))
+					LOG.error("Thread from test is not correctly using pools, please modify thread name to contain 'main'");
+				incorrectPoolUse = true;
+				return new CommonThreadPool(new ForkJoinPool(k));
+			}
+			return Executors.newFixedThreadPool(k);
+		}
 	}
 
 	/**