I'm working on a multi-threaded download manager. The code given below
is run by several threads. The code tries to read a set of bytes from
a URL and writes it to a random access file. Each threads writes to a
different part of the file, hence the need for seek().

byte [] data = new byte[1024];
int readLen;
while(canContinue && (readLen = bin.read(data)) != -1) {
    synchronized(dest) {
        dest.seek(start+completed);
        dest.write(data, 0, readLen);
        completed += readLen;
    }
}

Now when the user pauses the download, canContinue is set to false.
The problem with this scheme is that, it takes some time to pause all
the download threads. How can I stop the downloads instantaneously?

I've set readTimeout to 10secs. If I set it to a lower value, there
would be too many retries as my application tries to reestablish
connection when timeout occurs and the download is not paused. I there
any way to destroy a connection abruptly?