Index: src/main/java/org/apache/hadoop/hbase/util/PoolMap.java =================================================================== --- src/main/java/org/apache/hadoop/hbase/util/PoolMap.java (revision 1153935) +++ src/main/java/org/apache/hadoop/hbase/util/PoolMap.java (working copy) @@ -397,7 +397,8 @@ poolSizes.put(this, poolSize = new AtomicInteger(0)); } if (poolSize.intValue() >= maxSize) { - return null; + throw new IllegalStateException("poolSize ("+poolSize.intValue()+ + ") has reached " + maxSize); } poolSize.incrementAndGet(); }