HADOOP-15598. DataChecksum calculate checksum is contented on hashtable synchronization. Contributed by Prasanth Jayachandran.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/NativeCrc32.java

@@ -28,12 +28,12 @@ import com.google.common.annotations.VisibleForTesting;
  * natively.
  */
 class NativeCrc32 {
-  
+  private static final boolean isSparc = System.getProperty("os.arch").toLowerCase().startsWith("sparc");
   /**
    * Return true if the JNI-based native CRC extensions are available.
    */
   public static boolean isAvailable() {
-    if (System.getProperty("os.arch").toLowerCase().startsWith("sparc")) {
+    if (isSparc) {
       return false;
     } else {
       return NativeCodeLoader.isNativeCodeLoaded();