Hi Ryan,

Your example fails to take into account the cost of swapping threads in and out of swap space. You're simulating databases running a query and going to sleep forever, which is not realistic. I'm thinking of something along the lines of databases running a query every X seconds where X is a random value from 15 to 30 seconds. The cost of swapping threads in and out of swap is a lot more expensive than the use of a thread pool in this case.

Gili

On 19/02/2012 11:33 AM, Ryan How wrote:
Maybe the OS or something is smarter than it seems... I've had thousands of open threads and memory stays a lot lower than 1MB / thread. If it didn't my little laptop would chug!

I just ran a test then...

    public static void main(String[] args) {
        for (int i = 0; i < 1000; i++) {
            new Thread(new Runnable() {
                public void run() {
                    try {
                        Thread.sleep(100000000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }

    }

Windows Task Manager reports memory at 50,476K
Swap space rose by 70MB.

I mean, it is a little high for a program that does nothing, but it isn't 1GB!

On 19/02/2012 5:42 AM, cowwoc wrote:
# The default stack size for threads under 64-bit JVMs is 1MB. Source: http://www.oracle.com/technetwork/java/hotspotfaq-138619.html # At 64-bit with 512k stack (notice, this is smaller than the default) he is still limited to 32k threads and a whopping 16GB of memory gets used. You never even more memory to keep the heap around.
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