Java Best Practices - Need to write to file constantly - BufferedWriter?

Question

So I have a java process that needs to constantly append a new line to a file every 100 milliseconds. I am currently use BufferedWriter for this, but from what I have read, the BufferedWriter object should always be .close()'d when its finished.

If I did this, I would have to create a new BufferedWriter object every few milliseconds, which is not ideal. Are there any issues with creating one static BufferedWriter, and just .flush()'ing it after every write?

Finally, is BufferedWriter the best class to use for this, if performance is a concern? Are there any viable alternatives?

Thanks!

Answer 1

The BufferedWriter should be closed when it's finished . If you're doing something like logging, it's entirely acceptable to hold an open writer in the object responsible for the logging and then close it at the end of the run (or whenever you roll over to a new log file).

What you shouldn't do is simply open the writer and then discard the reference without closing it; this can leak resources, and in the case of something with buffering, might lose the last part of the output.

Answer 2

Are there any issues with creating one static BufferedWriter, and just .flush()'ing it after every write?

There is nothing wrong with a single, long-lived BufferedWriter . In fact it is a good idea. (Whether you use a static or something else is a different issue ... but that design decision does not impact on functionality and performance.)

Calling flush after each write is more questionable from a performance perspective. It will cause your application to make a lot of write syscalls ... which is expensive. I would only do that if you need the logging to be written immediately . The alternatively it to flush on a timer ... or not flush at all, and rely on the (final) close of the BufferedWriter to flush any outstanding data.

But either way, a long-lived BufferedWriter that you flush is likely to be better than creating, writing and closing lots of BufferedWriter objects.