Fixed low level bug in ConcurrentyOps where it was not clearing the w…

…orkspace in all situations,

resulting in really weird bugs in downstream customers of EJML

main/ejml-core/src/pabeles/concurrency/ConcurrencyOps.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Peter Abeles. All Rights Reserved.
+ * Copyright (c) 2023, Peter Abeles. All Rights Reserved.
  *
  * This file is part of Efficient Java Matrix Library (EJML).
  *
@@ -195,6 +195,9 @@ public static <T> void loopBlocks( int start, int endExclusive, GrowArray<T> wor
         final ForkJoinPool pool = ConcurrencyOps.pool;
         int numThreads = pool.getParallelism();
 
+        // Make sure there are no stale results, even if nothing is run
+        workspace.reset();
+
         int range = endExclusive - start;
         if (range == 0) // nothing to do here!
             return;
@@ -222,6 +225,9 @@ public static <T> void loopBlocks( int start, int endExclusive, int minBlock,
         final ForkJoinPool pool = ConcurrencyOps.pool;
         int numThreads = pool.getParallelism();
 
+        // Make sure there are no stale results, even if nothing is run
+        workspace.reset();
+
         int range = endExclusive - start;
         if (range == 0) // nothing to do here!
             return;
@@ -235,7 +241,6 @@ public static <T> void loopBlocks( int start, int endExclusive, int minBlock,
 
     private static <T> void runLoopBlocks( int start, int endExclusive, GrowArray<T> workspace,
                                            IntRangeObjectConsumer<T> consumer, ForkJoinPool pool, int blockSize ) {
-        workspace.reset();
         try {
             pool.submit(new IntRangeObjectTask<>(start, endExclusive, blockSize, workspace, consumer)).get();
         } catch (InterruptedException | ExecutionException e) {

main/ejml-dsparse/test/org/ejml/sparse/csc/mult/TestImplMultiplication_MT_DSCC.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Peter Abeles. All Rights Reserved.
+ * Copyright (c) 2023, Peter Abeles. All Rights Reserved.
  *
  * This file is part of Efficient Java Matrix Library (EJML).
  *
@@ -50,8 +50,12 @@ class TestImplMultiplication_MT_DSCC extends EjmlStandardJUnit {
             mult_s_s(5, 10, 5);
             mult_s_s(5, 5, 10);
         }
+
+        // See comment in mult_s_s. This triggered a bug
+        mult_s_s(10, 10, 0);
     }
 
+
     private void mult_s_s( int rowsA, int colsA, int colsB ) {
         int nz_a = RandomMatrices_DSCC.nonzero(rowsA, colsA, 0.05, 0.7, rand);
         int nz_b = RandomMatrices_DSCC.nonzero(colsA, colsB, 0.05, 0.7, rand);
@@ -62,6 +66,10 @@ private void mult_s_s( int rowsA, int colsA, int colsB ) {
         DMatrixSparseCSC expected = RandomMatrices_DSCC.rectangle(rowsA, colsB, nz_c, -1, 1, rand);
         DMatrixSparseCSC found = expected.copy();
 
+        // Make sure the work space is cleaned up. There was a bug where if b has zero columns stitching would
+        // throw an exception if this wasn't empty
+        workSpaceMT.grow();
+
         ImplMultiplication_DSCC.mult(a, b, expected, null, null);
         ImplMultiplication_MT_DSCC.mult(a, b, found, workSpaceMT);
         assertTrue(CommonOps_DSCC.checkStructure(found));