PEMap: set max initial capacity to 2MB if requested initial cap exceeds default initial capacity

Author: cosminbasca

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/common/PEMap.java

@@ -66,6 +66,13 @@ final class PEMap implements Iterable<DictKey> {
      */
     private static final int INITIAL_CAPACITY = 4;
 
+    /**
+     * Initial number of key/value pair entries that is allocated in the first entries array if the
+     * requested size is too large. Set to 2 MB
+     */
+    private static final int OBJ_ARRAY_SIZE_1_MB = 131072;
+    private static final int MAX_INITIAL_CAPACITY = OBJ_ARRAY_SIZE_1_MB * 2;
+
     /**
      * Maximum number of entries that are moved linearly forward if a key is removed.
      */
@@ -146,7 +153,11 @@ private PEMap(int initialCapacity, boolean isSet, boolean hasSideEffect) {
 
     private void init(int size) {
         if (size > INITIAL_CAPACITY) {
-            entries = new Object[(size << 1) < 0 ? MAX_ELEMENT_COUNT : size << 1];
+            int cap = size << 1;
+            if (cap < 0 || cap > MAX_INITIAL_CAPACITY) {
+                cap = MAX_INITIAL_CAPACITY;
+            }
+            entries = new Object[cap];
         }
     }