test/gc/stress/TestStressRSetCoarsening.java

rev 11275 : 8157153: TestStressRSetCoarsening fails with OOM
Reviewed-by:

@@ -101,10 +101,11 @@
     private static final long MB = 1024 * KB;
 
     private static final WhiteBox WB = WhiteBox.getWhiteBox();
 
     public final Object[][] storage;
+    public int storageUsedCount;
 
     /**
      * Number of objects per region. This is a test parameter.
      */
     public final int K;

@@ -159,10 +160,12 @@
         Runtime rt = Runtime.getRuntime();
         long used = rt.totalMemory() - rt.freeMemory();
         long totalFree = rt.maxMemory() - used;
         regionCount = (int) ((totalFree / regionSize) * heapFractionToAllocate);
         long toAllocate = regionCount * regionSize;
+        long freeMemoryLimit = totalFree - toAllocate;
+
         System.out.println("%% Test parameters");
         System.out.println("%%   Objects per region              : " + K);
         System.out.println("%%   Heap fraction to allocate       : " + (int) (heapFractionToAllocate * 100) + "%");
         System.out.println("%%   Regions to refresh to provoke GC: " + regsToRefresh);
 

@@ -210,13 +213,21 @@
         System.out.println("%%   K (objects in regions): " + K);
         System.out.println("%%   Object size           : " + objSize +
                 "  (sizeOf(new Object[" + N + "])");
         System.out.println("%%   Reference size        : " + refSize);
 
+        // Maximum number of objects to allocate is regionCount * K.
         storage = new Object[regionCount * K][];
-        for (int i = 0; i < storage.length; i++) {
-            storage[i] = new Object[N];
+        storageUsedCount = 0;
+
+        // Add objects as long as there is space in the array
+        // and we haven't used more memory than planned.
+        while (storageUsedCount < storage.length &&
+               (rt.maxMemory() - used) > freeMemoryLimit) {
+            storage[storageUsedCount++] = new Object[N];
+            // Update used memory
+            used = rt.totalMemory() - rt.freeMemory();
         }
     }
 
     public void go() throws InterruptedException {
         // threshold for sparce -> fine

@@ -253,11 +264,11 @@
                 for (int to = 0; to < regionCount; to++) {
                     // Select a celebrity object that we will install references to.
                     // The celebrity will be referred from all other regions.
                     // If the number of references after should be less than they
                     // were before, select NULL.
-                    Object celebrity = cur > pre ? storage[to * K] : null;
+                    Object celebrity = cur > pre ? storage[(to * K) % storageUsedCount] : null;
                     for (int from = 0; from < regionCount; from++) {
                         if (to == from) {
                             continue; // no need to refer to itself
                         }
 

@@ -295,11 +306,11 @@
                     }
                     // 'Refresh' storage elements for the region 'to'
                     // After that loop all 'old' objects in the region 'to'
                     // should become unreachable.
                     for (int k = 0; k < K; k++) {
-                        storage[(to * K + k) % storage.length] = new Object[N];
+                        storage[(to * K + k) % storageUsedCount] = new Object[N];
                     }
                 }
             }
         } catch (TimeoutException e) {
             System.out.println("%% TIMEOUT!!!");

@@ -331,12 +342,12 @@
      *
      * @param to region # to refer to
      * @param from region # to refer from
      * @param rn number of reference
      *
-     * @return Y index in the range: [0 ... K*regionCount -1]
+     * @return Y index in the range: [0 ... storageUsedCount-1]
      */
     private int getY(int to, int from, int rn) {
-        return ((rn * regionCount + to) / N + from * K) % (regionCount * K);
+        return ((rn * regionCount + to) / N + from * K) % (regionCount * K) % storageUsedCount;
     }
 }