5 ms·

> Finally, do you think maybe you might need to worry about buffering of System.out's stream? print() won't flush to the console unless you pass '\n' and auto-

> Finally, do you think maybe you might need to worry about buffering of System.out's stream? print() won't flush to the console unless you pass '\n' and auto-flushing is on. It will flush its internal buffer, but that's okay! The default System.out uses a BufferedOutputStream anyway: FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out); ... new PrintStream(new BufferedOutputStream(fdOut, 128), true) So using print() instead of write() shouldn't cause any extra system calls, although there many be a small CPU cost. Obvious, right? Don't you love java.io? :)

cbsmith 13y ago
> The default System.out uses a BufferedOutputStream anyway Yes, which is the _problem_, not the _solution_. To clarify: the problem isn't that the code makes too many syscalls.
- dlubarov 13y ago
  So what are you saying is the problem then? That writing to the BufferedOutputStream for each character is CPU-inefficient and he should be doing this? public static void main(String[] args) throws IOException { byte[] buffer = new byte[1 << 12]; for (;;) { int nRead = System.in.read(buffer); if (nRead == -1) return; System.out.write(buffer, 0, nRead); } } If so, fair enough, but it's reasonable to go with the simpler solution if you're not given any particular performance requirements.
  - cbsmith 13y ago
    No, I'm saying you are already using a BufferedInputStream and a BufferedOutputStream. That is the problem: you aren't guaranteeing your output matches your input. Try doing this: dd if=/dev/random of=test_file bs=4000 count=100 java YourClass < test_file > test_output diff test_file test_output
    - cbsmith 13y ago
      Here's the simpler, likely slower, but nonetheless actually correct solution: https://gist.github.com/cbsmith/9755809 https://gist.github.com/cbsmith/9755809
      - deleted 13y ago
        [deleted]
      - dlubarov 13y ago
        Oh, gotcha. The code above with "byte[] buffer" also works since write(byte[], int, int) flushes.

cbsmith 13y ago

> The default System.out uses a BufferedOutputStream anyway Yes, which is the _problem_, not the _solution_. To clarify: the problem isn't that the code makes too many syscalls.

dlubarov 13y ago
So what are you saying is the problem then? That writing to the BufferedOutputStream for each character is CPU-inefficient and he should be doing this? public static void main(String[] args) throws IOException { byte[] buffer = new byte[1 << 12]; for (;;) { int nRead = System.in.read(buffer); if (nRead == -1) return; System.out.write(buffer, 0, nRead); } } If so, fair enough, but it's reasonable to go with the simpler solution if you're not given any particular performance requirements.
- cbsmith 13y ago
  No, I'm saying you are already using a BufferedInputStream and a BufferedOutputStream. That is the problem: you aren't guaranteeing your output matches your input. Try doing this: dd if=/dev/random of=test_file bs=4000 count=100 java YourClass < test_file > test_output diff test_file test_output
  - cbsmith 13y ago
    Here's the simpler, likely slower, but nonetheless actually correct solution: https://gist.github.com/cbsmith/9755809 https://gist.github.com/cbsmith/9755809
    - deleted 13y ago
      [deleted]
    - dlubarov 13y ago
      Oh, gotcha. The code above with "byte[] buffer" also works since write(byte[], int, int) flushes.