private static int reprobe_limit( int len ) {
    return REPROBE_LIMIT + (len>>4);
  }
Get and clear the current count of reprobes.  Reprobes happen on key
 collisions, and a high reprobe rate may indicate a poor hash function or
 weaknesses in the table resizing function.
 @return the count of reprobes since the last call to {@link #reprobes}
 or since the table was created.
jctools-core/src/main/java/org/jctools/maps/NonBlockingHashMapLong.java