@Override
        public void flush() throws IOException {
            bufferedOut.flush();
            long newPos = fileOut.getChannel().position();
            if (newPos >= lastDropPosition + bufferSize) {
                nativeIO.dropPartialFileFromCache(fileOut.getFD(), lastDropPosition, newPos, true);
                lastDropPosition = newPos;
            }
        }
File output stream that signals to kernel to drop previous pages after write
container-core/src/main/java/com/yahoo/container/logging/LogFileHandler.java