Read file at a certain rate in Java

Question

Is there an article/algorithm on how I can read a long file at a certain rate?

Say I do not want to pass 10 KB/sec while issuing reads.

Answer 1

It depends a little on whether you mean "don't exceed a certain rate" or "stay close to a certain rate."

If you mean "don't exceed", you can guarantee that with a simple loop:

 while not EOF do
    read a buffer
    Thread.wait(time)
    write the buffer
 od

The amount of time to wait is a simple function of the size of the buffer; if the buffer size is 10K bytes, you want to wait a second between reads.

If you want to get closer than that, you probably need to use a timer.

• create a Runnable to do the reading
• create a Timer with a TimerTask to do the reading
• schedule the TimerTask n times a second.

If you're concerned about the speed at which you're passing the data on to something else, instead of controlling the read, put the data into a data structure like a queue or circular buffer, and control the other end; send data periodically. You need to be careful with that, though, depending on the data set size and such, because you can run into memory limitations if the reader is very much faster than the writer.