@Override
  public String toString() {
    StringBuilder sb = new StringBuilder(1024);
    sb.append("Allocator requested size ").append(requestedSize);
    sb.append(" for bucket ").append(bucketIndex);
    return sb.toString();
  }
Thrown by {@link BucketAllocator#allocateBlock(int)} when cache is full for the requested size
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/CacheFullException.java