Howdy all!
I'm new to the list, so forgive me if this has been gone over before.
I've written a program that needs to read/write lots of cache files to
disk. They are around 100k a piece though it can vary quite a bit.
In response to user action I need to load 2-5 of these cache files and
update the GUI. On windows and linux the read times for these cache
images average around 250ms. However on OS X the mean time to load
rises to 450ms with some exceeding 1200ms.
I set out to find what was causing this bottleneck, so I wrote this
small class to test IO performance:
public class RawIOBenchmark {
long testStart, testEnd;
public RawIOBenchmark(File fileToTest) throws Exception {
long result = testStraightFileIO(fileToTest);
System.out.println("Straight File IO > took = " + result + "
milliseconds.");
}
private long testStraightFileIO(File fileToTest) throws Exception {
byte[] buffer = new byte[new Long(fileToTest.length()).intValue()];
FileInputStream fis = new FileInputStream(fileToTest);
testStart = System.currentTimeMillis();
int bytesRead = 0;
int read = fis.read(buffer, 0, buffer.length);
bytesRead += read;
while(bytesRead < buffer.length && read != -1) {
read = fis.read(buffer, bytesRead, buffer.length - bytesRead);
bytesRead += read;
}
System.out.println("bytes read:"+bytesRead);
testEnd = System.currentTimeMillis();
return (testEnd - testStart);
}
public static void main(String[] args) throws Exception {
System.out.println("args.length = " + args.length);
if(args.length != 1) {
System.out.println("Please specify file or directory to test.");
System.exit(-1);
}
File fileToTest = new File(args[0]);
if(fileToTest.isFile())
new RawIOBenchmark(fileToTest);
else if(fileToTest.isDirectory()) {
File[] files = fileToTest.listFiles();
for (int i = 0; i < files.length; i++) {
File file = files[i];
new RawIOBenchmark(file);
}
}
}
}
I pointed this little test class at a directory filled with 1 - 1.5Meg
jpegs. About 95 of them. Here's what I wound up with:
Min: 25ms (Faster then any other platform)
Max: 8935ms (Slower by a factor of 5 then any other platform)
Mean: 2030ms (Slower by half then any other platform)
I've played with memory settings, from 64m to 1024m. I've turned on
verbose garbage collection. Nothing seems to explain it.
Am I doing something horribly wrong? Anyone else run into this?
Thanks in advance,
- Will
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