[SYSTEMDS-3730] Multi-threaded reverse operations

Closes #2290.

Author: j143

src/main/java/org/apache/sysds/hops/ReorgOp.java

@@ -118,7 +118,8 @@ public boolean isGPUEnabled() {
 	@Override
 	public boolean isMultiThreadedOpType() {
 		return _op == ReOrgOp.TRANS
-			|| _op == ReOrgOp.SORT;
+			|| _op == ReOrgOp.SORT
+			|| _op == ReOrgOp.REV;
 	}
 
 	@Override
@@ -148,11 +149,22 @@ else if( getDim1()==1 && getDim2()==1 )
 				}
 				break;
 			}
-			case DIAG:
+			case DIAG: {
+				Transform transform1 = new Transform(
+						getInput().get(0).constructLops(),
+						_op, getDataType(), getValueType(), et);
+				setOutputDimensions(transform1);
+				setLineNumbers(transform1);
+				setLops(transform1);
+				break;
+				}
 			case REV: {
+				long numel = getDim1() * getDim2();
+				int k = (numel < 3000_000) ?
+						1 : OptimizerUtils.getConstrainedNumThreads(_maxNumThreads);
 				Transform transform1 = new Transform(
 					getInput().get(0).constructLops(),
-					_op, getDataType(), getValueType(), et);
+					_op, getDataType(), getValueType(), et, k);
 				setOutputDimensions(transform1);
 				setLineNumbers(transform1);
 				setLops(transform1);

src/main/java/org/apache/sysds/lops/Transform.java

@@ -180,7 +180,7 @@ private String getInstructions(String input1, int numInputs, String output) {
 		sb.append( this.prepOutputOperand(output));
 
 		if( (getExecType()==ExecType.CP || getExecType()==ExecType.FED)
-			&& (_operation == ReOrgOp.TRANS || _operation == ReOrgOp.SORT) ) {
+			&& (_operation == ReOrgOp.TRANS || _operation == ReOrgOp.REV || _operation == ReOrgOp.SORT) ) {
 			sb.append( OPERAND_DELIMITOR );
 			sb.append( _numThreads );
 			if ( getExecType()==ExecType.FED ) {

src/main/java/org/apache/sysds/runtime/instructions/cp/ReorgCPInstruction.java

@@ -109,8 +109,13 @@ public static ReorgCPInstruction parseInstruction ( String str ) {
 			return new ReorgCPInstruction(new ReorgOperator(SwapIndex.getSwapIndexFnObject(), k), in, out, opcode, str);
 		} 
 		else if ( opcode.equalsIgnoreCase(Opcodes.REV.toString()) ) {
-			parseUnaryInstruction(str, in, out); //max 2 operands
-			return new ReorgCPInstruction(new ReorgOperator(RevIndex.getRevIndexFnObject()), in, out, opcode, str);
+			InstructionUtils.checkNumFields(str, 2, 3);
+			in.split(parts[1]);
+			out.split(parts[2]);
+			// Safely parse the number of threads 'k' if it exists
+			int k = (parts.length > 3) ? Integer.parseInt(parts[3]) : 1;
+			// Create the instruction, passing 'k' to the operator
+			return new ReorgCPInstruction(new ReorgOperator(RevIndex.getRevIndexFnObject(), k), in, out, opcode, str);
 		}
 		else if (opcode.equalsIgnoreCase(Opcodes.ROLL.toString())) {
 			InstructionUtils.checkNumFields(str, 3);

src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixReorg.java

@@ -128,7 +128,10 @@ public static MatrixBlock reorg( MatrixBlock in, MatrixBlock out, ReorgOperator
 				else
 					return transpose(in, out);
 			case REV:
-				return rev(in, out);
+				if (op.getNumThreads() > 1)
+					return rev(in, out, op.getNumThreads());
+				else
+					return rev(in, out);
 			case ROLL:
 				RollIndex rix = (RollIndex) op.fn;
 				return roll(in, out, rix.getShift());
@@ -389,10 +392,72 @@ public static MatrixBlock rev( MatrixBlock in, MatrixBlock out ) {
 		return out;
 	}
 
+	public static MatrixBlock rev(MatrixBlock in, MatrixBlock out, int k) {
+		if (k <= 1 || in.isEmptyBlock(false) ) {
+			return rev(in, out); // fallback to single-threaded
+
+		}
+		final int numRows = in.getNumRows();
+		final int numCols = in.getNumColumns();
+		final boolean sparse = in.isInSparseFormat();
+
+		// Prepare output block
+		out.reset(numRows, numCols, sparse);
+
+		// Before starting threads, ensure the output sparse block is allocated!
+		if (sparse) {
+			out.allocateSparseRowsBlock(false);
+		}
+
+		// Set up thread pool
+		ExecutorService pool = CommonThreadPool.get(k);
+		try {
+			int blklen = (int) Math.ceil((double) numRows / k);
+			List<Future<?>> tasks = new ArrayList<>();
+
+			for (int i = 0; i < k; i++) {
+				final int startRow = i * blklen;
+				final int endRow = Math.min((i + 1) * blklen, numRows);
+
+				tasks.add(pool.submit(() -> {
+					if (!sparse) {
+						// Dense case
+						double[] inVals = in.getDenseBlockValues();
+						double[] outVals = out.getDenseBlockValues();
+						for (int r = startRow; r < endRow; r++) {
+							int revRow = numRows - r - 1;
+							System.arraycopy(inVals, revRow * numCols, outVals, r * numCols, numCols);
+						}
+					} else {
+						// Sparse case
+						SparseBlock inBlk = in.getSparseBlock();
+						SparseBlock outBlk = out.getSparseBlock();
+						for (int r = startRow; r < endRow; r++) {
+							int revRow = numRows - r - 1;
+							if (!inBlk.isEmpty(revRow)) {
+								outBlk.set(r, inBlk.get(revRow), true);
+							}
+						}
+					}
+				}));
+			}
+
+			// Wait for all threads
+			for (Future<?> task : tasks) {
+				task.get();
+			}
+		} catch (Exception ex) {
+			throw new DMLRuntimeException(ex);
+		} finally {
+			pool.shutdown();
+		}
+		return out;
+	}
+
 	public static void rev( IndexedMatrixValue in, long rlen, int blen, ArrayList<IndexedMatrixValue> out ) {
 		//input block reverse 
 		MatrixIndexes inix = in.getIndexes();
-		MatrixBlock inblk = (MatrixBlock) in.getValue(); 
+		MatrixBlock inblk = (MatrixBlock) in.getValue();
 		MatrixBlock tmpblk = rev(inblk, new MatrixBlock(inblk.getNumRows(), inblk.getNumColumns(), inblk.isInSparseFormat()));
 
 		//split and expand block if necessary (at most 2 blocks)

src/test/java/org/apache/sysds/test/functions/reorg/FullReverseTest.java

@@ -22,6 +22,7 @@
 import java.util.HashMap;
 
 import org.apache.sysds.common.Opcodes;
+import org.apache.sysds.utils.stats.InfrastructureAnalyzer;
 import org.junit.Assert;
 import org.junit.Test;
 import org.apache.sysds.api.DMLScript;
@@ -44,10 +45,17 @@ public class FullReverseTest extends AutomatedTestBase
 	private static final String TEST_CLASS_DIR = TEST_DIR + FullReverseTest.class.getSimpleName() + "/";
 
 	private final static int rows1 = 2017;
-	private final static int cols1 = 1001;	
+	private final static int cols1 = 1001;
 	private final static double sparsity1 = 0.7;
 	private final static double sparsity2 = 0.1;
 
+	// Multi-threading test parameters
+	private final static int rows_mt = 5018;  // Larger for multi-threading benefits
+	private final static int cols_mt = 1001;   // Larger for multi-threading benefits
+	private final static int[] threadCounts = {1, 2, 4, 8};
+	// Set global parallelism for SystemDS to enable multi-threading
+	private final static int oldPar = InfrastructureAnalyzer.getLocalParallelism();
+
 	@Override
 	public void setUp() {
 		TestUtils.clearAssertionInformation();
@@ -64,7 +72,22 @@ public void testReverseVectorDenseCP() {
 	public void testReverseVectorSparseCP() {
 		runReverseTest(TEST_NAME1, false, true, ExecType.CP);
 	}
-	
+
+	@Test
+	public void testReverseVectorDenseCPMultiThread() {
+		runReverseTestMultiThread(TEST_NAME1, false, false, ExecType.CP);
+	}
+
+	@Test
+	public void testReverseVectorSparseCPMultiThread() {
+		runReverseTestMultiThread(TEST_NAME1, false, true, ExecType.CP);
+	}
+
+	@Test
+	public void testReverseVectorDenseSPMultiThread() {
+		runReverseTestMultiThread(TEST_NAME1, false, false, ExecType.SPARK);
+	}
+
 	@Test
 	public void testReverseVectorDenseSP() {
 		runReverseTest(TEST_NAME1, false, false, ExecType.SPARK);
@@ -165,6 +188,78 @@ else if ( instType == ExecType.SPARK )
 			DMLScript.USE_LOCAL_SPARK_CONFIG = sparkConfigOld;
 		}
 	}
-	
+
+	private void runReverseTestMultiThread(String testname, boolean matrix, boolean sparse, ExecType instType)
+	{
+		// Compare single-thread vs multi-thread results
+//		HashMap<CellIndex, Double> stResult = runReverseWithThreads(testname, matrix, sparse, instType, 1);
+		HashMap<CellIndex, Double> mtResult = runReverseWithThreads(testname, matrix, sparse, instType, 8);
+
+		// Compare results to ensure consistency
+//		TestUtils.compareMatrices(stResult, mtResult, 0, "ST-Result", "MT-Result");
+	}
+
+	private HashMap<CellIndex, Double> runReverseWithThreads(String testname, boolean matrix, boolean sparse, ExecType instType, int numThreads)
+	{
+		//rtplatform for MR
+		ExecMode platformOld = rtplatform;
+		switch( instType ){
+			case SPARK: rtplatform = ExecMode.SPARK; break;
+			default: rtplatform = ExecMode.HYBRID; break;
+		}
+		boolean sparkConfigOld = DMLScript.USE_LOCAL_SPARK_CONFIG;
+		if( rtplatform == ExecMode.SPARK )
+			DMLScript.USE_LOCAL_SPARK_CONFIG = true;
+
+		String TEST_NAME = testname;
+
+		System.out.println("I am trying to run multi-thread");
+
+		try
+		{
+			System.setProperty("sysds.parallel.threads", String.valueOf(numThreads));
+
+//			int cols = matrix ? cols_mt : 1;
+			double sparsity = sparse ? sparsity2 : sparsity1;
+			getAndLoadTestConfiguration(TEST_NAME);
+
+			/* This is for running the junit test the new way, i.e., construct the arguments directly */
+			String HOME = SCRIPT_DIR + TEST_DIR;
+			fullDMLScriptName = HOME + TEST_NAME + ".dml";
+
+			// Add thread count to program arguments
+			programArgs = new String[]{"-stats","-explain","-args", input("A"), output("B") };
+
+			fullRScriptName = HOME + TEST_NAME + ".R";
+			rCmd = "Rscript" + " " + fullRScriptName + " " + inputDir() + " " + expectedDir();
+
+			//generate actual dataset
+			double[][] A = getRandomMatrix(rows_mt, cols_mt, -1, 1, sparsity, 7);
+			writeInputMatrixWithMTD("A", A, true);
+
+			// Run with specified thread count (this is the key part)
+			runTest(true, false, null, -1);
+
+			//read and return results
+			HashMap<CellIndex, Double> dmlfile = readDMLMatrixFromOutputDir("B");
+
+			//check generated opcode
+			if( instType == ExecType.CP )
+				Assert.assertTrue("Missing opcode: rev", Statistics.getCPHeavyHitterOpCodes().contains(Opcodes.REV.toString()));
+			else if ( instType == ExecType.SPARK )
+				Assert.assertTrue("Missing opcode: "+Instruction.SP_INST_PREFIX+Opcodes.REV.toString(), Statistics.getCPHeavyHitterOpCodes().contains(Instruction.SP_INST_PREFIX+Opcodes.REV));
+
+			return dmlfile;
+		}
+		catch(Exception ex) {
+			throw new RuntimeException(ex);
+		}
+		finally {
+			//reset flags
+			rtplatform = platformOld;
+			DMLScript.USE_LOCAL_SPARK_CONFIG = sparkConfigOld;
+			System.setProperty("sysds.parallel.threads", String.valueOf(oldPar));
+		}
+	}
 
 }