Index: src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java =================================================================== --- src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java (revision 1545156) +++ src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java (working copy) @@ -625,6 +625,13 @@ FSDataOutputStream nextHdfsOut = null; if (nextWriter instanceof SequenceFileLogWriter) { nextHdfsOut = ((SequenceFileLogWriter)nextWriter).getWriterFSDataOutputStream(); + // perform the costly sync before we get the lock to roll writers. + try { + nextWriter.sync(); + } catch (IOException e) { + // optimization failed, no need to abort here. + LOG.warn("pre-sync failed", e); + } } synchronized (updateLock) {