Index: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java =================================================================== --- hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java (revision 1524813) +++ hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java (working copy) @@ -1079,7 +1079,9 @@ if (tempWriter != null) tempWriter.sync(); } } - this.syncedTillHere = Math.max(this.syncedTillHere, doneUpto); + synchronized (this.updateLock) { + this.syncedTillHere = Math.max(this.syncedTillHere, doneUpto); + } this.metrics.finishSync(EnvironmentEdgeManager.currentTimeMillis() - now); // TODO: preserving the old behavior for now, but this check is strange. It's not