public synchronized OutputStream open() {
        try {
            close();
            fileOutputStream = new FileOutputStream(file, true);
        } catch (FileNotFoundException e) {
            throw new RuntimeException("Unable to open output stream", e);
        }
        return fileOutputStream;
    }
@author Ulf Lilleengen
@since 5.1
Should only be used internally in the log library
vespalog/src/main/java/com/yahoo/log/FileLogTarget.java