HADOOP-17901. Performance degradation in Text.append() after HADOOP-1… (#3411)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/Text.java

@@ -268,8 +268,7 @@ public class Text extends BinaryComparable
    */
   public void append(byte[] utf8, int start, int len) {
     byte[] original = bytes;
-    int capacity = Math.max(length + len, length + (length >> 1));
-    if (ensureCapacity(capacity)) {
+    if (ensureCapacity(length + len)) {
       System.arraycopy(original, 0, bytes, 0, length);
     }
     System.arraycopy(utf8, start, bytes, length, len);
@@ -302,7 +301,10 @@ public class Text extends BinaryComparable
    */
   private boolean ensureCapacity(final int capacity) {
     if (bytes.length < capacity) {
-      bytes = new byte[capacity];
+      // Try to expand the backing array by the factor of 1.5x
+      // (by taking the current size + diving it by half)
+      int targetSize = Math.max(capacity, bytes.length + (bytes.length >> 1));
+      bytes = new byte[targetSize];
       return true;
     }
     return false;