Index: src/main/java/org/apache/hadoop/hbase/regionserver/Store.java =================================================================== --- src/main/java/org/apache/hadoop/hbase/regionserver/Store.java (revision 1230904) +++ src/main/java/org/apache/hadoop/hbase/regionserver/Store.java (working copy) @@ -853,7 +853,12 @@ * @return True if we should run a major compaction. */ boolean isMajorCompaction() throws IOException { - return isMajorCompaction(storefiles); + this.lock.readLock().lock(); + try{ + return isMajorCompaction(storefiles); + }finally{ + this.lock.readLock().unlock(); + } } /* @@ -875,6 +880,10 @@ if (filesToCompact.size() == 1) { // Single file StoreFile sf = filesToCompact.get(0); + if(sf.getReader() == null){ + LOG.debug("StoreFile " + sf + " has null Reader"); + return result; + } long oldest = (sf.getReader().timeRangeTracker == null) ? Long.MIN_VALUE :