Hi Luke,
Sorry, I did miss your follow-up post. When I got your email I dug out the
modified code. I'm even more sorry to say that I introduced a dumb bug which
artificially increased the speed. I accidentally put i += size, instead of i
+= buffer.length. That artificially boosted the speed hugely by outputting a
small file duh.
Anyway with my modified code (posted below) I get:
11-28 20:58:09.859: INFO/speedtest(850): speed test a: 1370
11-28 20:58:09.889: INFO/speedtest(850): speed test b: 31
which I think is in keeping with your figures (I wouldn't my mental
arithmetic). I do note however that this idiom in your code:
FileInputStream fis = openFileInput("speedtest");
fis.read(array);
fis.close();
is unreliable and only works by chance - in general there is no guarantee
that any read will fill a buffer unless otherwise noted in the
documentation.
Hope you didn't waste too much time on my mistake!
Tom.
2008/11/28 ______ <[EMAIL PROTECTED]>
>
> I ran some more extensive tests and got the following:
>
> WRITING:
> one byte at a time written to BufferedOutputStream: 155kb/sec
> whole array written to BufferedOutputStream: 450kb/sec
> one byte at a time written to FileOutputStream: 8kb/sec
> whole array written to FileOutputStream: 453kb/sec
>
> READING:
> one byte at a time read from BufferedInputStream: 221kb/sec
> whole array read from BufferedInputStream: 47850kb/sec
> one byte at a time read from FileInputStream: 9kb/sec
> whole array read from FileInputStream: 31604kb/sec
>
> (The reading results are a little artificial as I didn't attempt any
> sort of buffer flush between tests...)
>
> This shows that (in the writing case) writing single bytes to a
> BufferedOutputStream has about a 3x overhead over writing an array to
> a BufferedOutputStream or FileOutputStream, but writing whole arrays
> to either buffered or unbuffered streams still does not come close to
> the numbers you gave. (My arrays are much larger than the default
> buffer size of 8kb, but that shouldn't make much difference if you
> were reading actual IO throughput numbers...)
>
> Anyway the overall result is still an order of magnitude slower than
> it should be, in the fastest case (using arrays).
>
> The code is as follows. (The two slowest cases are commented-out.) I
> get similar numbers using NIO channels. What am I doing differently
> from you?
>
> --
>
> int size = 5 * 1024 * 1024;
> byte[] array = new byte[size];
>
> long startTime = System.currentTimeMillis();
> BufferedOutputStream bos = new
> BufferedOutputStream(openFileOutput
> ("speedtest", MODE_PRIVATE));
> for (int i = 0; i < size; i++)
> bos.write((byte) 0);
> bos.close();
> Log.i("speedtest", "one byte at a time written to
> BufferedOutputStream: " + ((size / 1024.0) / ((System.currentTimeMillis
> () - startTime) / 1000.0)) + "kb/sec");
>
> // startTime = System.currentTimeMillis();
> // FileOutputStream fos = openFileOutput("speedtest",
> MODE_PRIVATE);
> // for (int i = 0; i < size; i++)
> // fos.write((byte) 0);
> // fos.close();
> // Log.i("speedtest", "one byte at a time written to
> FileOutputStream: " + ((size / 1024.0) / ((System.currentTimeMillis()
> - startTime) / 1000.0)) + "kb/sec");
>
> startTime = System.currentTimeMillis();
> bos = new
> BufferedOutputStream(openFileOutput("speedtest",
> MODE_PRIVATE));
> bos.write(array);
> bos.close();
> Log.i("speedtest", "whole array written to
> BufferedOutputStream: "
> + ((size / 1024.0) / ((System.currentTimeMillis() - startTime) /
> 1000.0)) + "kb/sec");
>
> startTime = System.currentTimeMillis();
> FileOutputStream fos = openFileOutput("speedtest",
> MODE_PRIVATE);
> fos.write(array);
> fos.close();
> Log.i("speedtest", "whole array written to
> FileOutputStream: " +
> ((size / 1024.0) / ((System.currentTimeMillis() - startTime) /
> 1000.0)) + "kb/sec");
>
> startTime = System.currentTimeMillis();
> BufferedInputStream bis = new
> BufferedInputStream(openFileInput
> ("speedtest"));
> for (int i = 0; i < size; i++)
> bis.read();
> bis.close();
> Log.i("speedtest", "one byte at a time read from
> BufferedInputStream: " + ((size / 1024.0) / ((System.currentTimeMillis
> () - startTime) / 1000.0)) + "kb/sec");
>
> // startTime = System.currentTimeMillis();
> // FileInputStream fis = openFileInput("speedtest");
> // for (int i = 0; i < size; i++)
> // fis.read();
> // fis.close();
> // Log.i("speedtest", "one byte at a time read from
> FileInputStream:
> " + ((size / 1024.0) / ((System.currentTimeMillis() - startTime) /
> 1000.0)) + "kb/sec");
>
> startTime = System.currentTimeMillis();
> bis = new
> BufferedInputStream(openFileInput("speedtest"));
> bis.read(array);
> bis.close();
> Log.i("speedtest", "array read from
> BufferedInputStream: " +
> ((size / 1024.0) / ((System.currentTimeMillis() - startTime) /
> 1000.0)) + "kb/sec");
>
> startTime = System.currentTimeMillis();
> FileInputStream fis = openFileInput("speedtest");
> fis.read(array);
> fis.close();
> Log.i("speedtest", "array read from FileInputStream:
> " + ((size /
> 1024.0) / ((System.currentTimeMillis() - startTime) / 1000.0)) + "kb/
> sec");
>
> deleteFile("speedtest");
>
> >
>
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