Index: hbase-hadoop1-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionSourceImpl.java =================================================================== --- hbase-hadoop1-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionSourceImpl.java (revision 1459787) +++ hbase-hadoop1-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionSourceImpl.java (working copy) @@ -49,7 +49,9 @@ MetricsRegionAggregateSourceImpl aggregate) { this.regionWrapper = regionWrapper; agg = aggregate; - agg.register(this); + synchronized (agg) { + agg.register(this); + } LOG.debug("Creating new MetricsRegionSourceImpl for table " + regionWrapper.getTableName() + @@ -83,7 +85,9 @@ @Override public void close() { closed = true; - agg.deregister(this); + synchronized (agg) { + agg.deregister(this); + } LOG.trace("Removing region Metrics: " + regionWrapper.getRegionName()); registry.removeMetric(regionPutKey);