[MINOR] Dependency tasks enable via Log4j

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

@@ -30,12 +30,12 @@
 import org.apache.sysds.runtime.DMLRuntimeException;
 
 public class DependencyTask<E> implements Comparable<DependencyTask<?>>, Callable<E> {
-	public static final boolean ENABLE_DEBUG_DATA = false; // explain task graph
 	protected static final Log LOG = LogFactory.getLog(DependencyTask.class.getName());
+	/** debugging dependency tasks only used if LOG.isDebugEnabled */
+	public List<DependencyTask<?>> _dependencyTasks = null;
 
 	private final Callable<E> _task;
 	protected final List<DependencyTask<?>> _dependantTasks;
-	public List<DependencyTask<?>> _dependencyTasks = null; // only for debugging
 	private CompletableFuture<Future<?>> _future;
 	private int _rdy = 0;
 	private Integer _priority = 0;

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

@@ -92,7 +92,7 @@ public List<Future<Future<?>>> submitAll(List<? extends Callable<?>> tasks,
 	public List<Object> submitAllAndWait(List<DependencyTask<?>> dtasks)
 		throws ExecutionException, InterruptedException {
 		List<Object> res = new ArrayList<>();
-		if(DependencyTask.ENABLE_DEBUG_DATA) {
+		if(LOG.isDebugEnabled()) {
 			if (dtasks != null && dtasks.size() > 0)
 				explainTaskGraph(dtasks);
 		}
@@ -172,7 +172,7 @@ public static List<DependencyTask<?>> createDependencyTasks(List<? extends Calla
 			DependencyTask<?> t = ret.get(i);
 			for(Callable<?> dep : deps) {
 				DependencyTask<?> dt = map.get(dep);
-				if(DependencyTask.ENABLE_DEBUG_DATA) {
+				if(LOG.isDebugEnabled()) {
 					t._dependencyTasks = t._dependencyTasks == null ? new ArrayList<>() : t._dependencyTasks;
 					t._dependencyTasks.add(dt);
 				}
@@ -226,10 +226,12 @@ public static void explainTaskGraph(List<DependencyTask<?>> tasks) {
 			sbs[level].append(offsets[level]);
 			sbs[level].append(entry.getKey().toString()+"\n");
 		}
-		System.out.println("EXPlAIN (TASK-GRAPH):");
+		StringBuilder sb = new StringBuilder("\n");
+		sb.append("EXPlAIN (TASK-GRAPH):");
 		for (int i=0; i<sbs.length; i++) {
-			System.out.println(sbs[i].toString());
+			sb.append(sbs[i].toString());
 		}
+		LOG.debug(sb.toString());
 
 	}
 }

src/test/java/org/apache/sysds/test/component/frame/transform/TransformLogger.java

@@ -0,0 +1,100 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.sysds.test.component.frame.transform;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.util.List;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.log4j.Level;
+import org.apache.log4j.Logger;
+import org.apache.log4j.spi.LoggingEvent;
+import org.apache.sysds.common.Types.ValueType;
+import org.apache.sysds.runtime.frame.data.FrameBlock;
+import org.apache.sysds.runtime.transform.encode.CompressedEncode;
+import org.apache.sysds.runtime.transform.encode.EncoderFactory;
+import org.apache.sysds.runtime.transform.encode.MultiColumnEncoder;
+import org.apache.sysds.runtime.util.DependencyTask;
+import org.apache.sysds.runtime.util.DependencyThreadPool;
+import org.apache.sysds.test.LoggingUtils;
+import org.apache.sysds.test.LoggingUtils.TestAppender;
+import org.apache.sysds.test.TestUtils;
+import org.junit.Test;
+
+public class TransformLogger {
+	protected static final Log LOG = LogFactory.getLog(TransformLogger.class.getName());
+
+	private final FrameBlock data;
+
+	public TransformLogger() {
+		try {
+
+			data = TestUtils.generateRandomFrameBlock(100, new ValueType[] {ValueType.UINT4}, 231);
+			data.setSchema(new ValueType[] {ValueType.INT32});
+		}
+		catch(Exception e) {
+			e.printStackTrace();
+			fail(e.getMessage());
+			throw e;
+		}
+	}
+
+	@Test
+	public void testDummyCode() {
+		test("{dummycode:[C1]}");
+	}
+
+	public void test(String spec) {
+		final TestAppender appender = LoggingUtils.overwrite();
+
+		try {
+			Logger.getLogger(CompressedEncode.class).setLevel(Level.DEBUG);
+			Logger.getLogger(DependencyThreadPool.class).setLevel(Level.DEBUG);
+			Logger.getLogger(DependencyTask.class).setLevel(Level.DEBUG);
+
+			FrameBlock meta = null;
+			MultiColumnEncoder encoderNormal = EncoderFactory.createEncoder(spec, data.getColumnNames(),
+				data.getNumColumns(), meta);
+			encoderNormal.encode(data, 10);
+
+			final List<LoggingEvent> log = LoggingUtils.reinsert(appender);
+
+			boolean containsMessage = false;
+			for(LoggingEvent l : log) {
+				containsMessage |= l.getMessage().toString().contains("EXPlAIN (TASK-GRAPH):");
+			}
+
+			assertTrue(containsMessage);
+
+		}
+		catch(Exception e) {
+			e.printStackTrace();
+			fail(e.getMessage());
+		}
+		finally {
+			LoggingUtils.reinsert(appender);
+		}
+
+	}
+
+}