@Override
      public AtomicInteger load(Class<T> key) throws Exception {
        return new AtomicInteger();
      }
A global compressor/decompressor pool used to save and reuse (possibly native)
compression/decompression codecs. Copied from the class of the same name in hadoop-common and
augmented to improve borrow/return performance.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/compress/CodecPool.java