barrier causes random deadlocks in JTP mode for non-tiny ranges #8

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opened 2021-10-03 02:36:00 +00:00 by morgwai · 1 comment

morgwai commented

2021-10-03 02:36:00 +00:00

(Migrated from git.qoto.org)

the following code:

public static class SumKernel extends Kernel {

	double[] a;
	double[] b;
	double[] c;

	public void execute(double[] a, double[] b, double[] c) {
		this.a = a;
		this.b = b;
		this.c = c;
		execute(Range.create(a.length));
	}

	@Override
	public void run() {
		int i = getGlobalId();
		c[i] = a[i] + b[i];
		globalBarrier();
	}
};

public static void main(String[] args) throws InterruptedException {
	var random = new Random();
	int len = 1000_000;
	double[] a = new double[len];
	double[] b = new double[len];
	for (int i = 0; i < len; i++) {
		a[i] = random.nextDouble();
		b[i] = random.nextDouble();
	}

	for (int i = 0; i < 20; i++) {
		double[] c = new double[len];
		var thread = new Thread(() -> {
			var kernel = new SumKernel();
			kernel.setExecutionMode(EXECUTION_MODE.JTP);
			kernel.execute(a, b, c);
			kernel.dispose();
		});

		System.out.println();
		System.out.println("starting...");
		var start = System.currentTimeMillis();
		thread.start();
		thread.join(20_000l);
		if ( ! thread.isAlive()) {
			System.out.println("finished in " + (System.currentTimeMillis() - start));
			continue;
		}
		System.out.println("still running after 20s, interrupting...");
		thread.interrupt();
		thread.join(2_000l);
		if ( ! thread.isAlive()) {
			System.out.println("interrupted successful.");
			continue;
		}
		System.out.println("still running after interrupt, stopping...");
		thread.stop();
		thread.join(1_000l);
		if (thread.isAlive()) {
			System.out.println("still running after stop.");
		} else {
			System.out.println("stop successful.");
		}
	}
}

gives me an output similar to the below:

starting...
WARNING: Aparapi is running on an untested OpenCL platform version: OpenCL 3.0
finished in 5096

starting...
finished in 5069

starting...
finished in 4945

starting...
still running after 20s, interrupting...
still running after interrupt, stopping...
stop successful.

starting...
finished in 5278

starting...
still running after 20s, interrupting...
still running after interrupt, stopping...
stop successful.

starting...
finished in 5286

starting...
finished in 5318

starting...
finished in 5637

starting...
finished in 6113

starting...
finished in 6939

starting...
finished in 7115

starting...
finished in 7830

starting...
finished in 6700

starting...
finished in 6603

starting...
finished in 6662

starting...
still running after 20s, interrupting...
still running after interrupt, stopping...
stop successful.

starting...
finished in 6820

starting...
finished in 6923

starting...
finished in 7167

It works perfectly fine on GPU (without kernel.setExecutionMode(EXECUTION_MODE.JTP); line) or without the globalBarrier(); line.

My environment:
aparapi 3.0.0
openJDK 11 (11.0.11+9-0ubuntu2~18.04)
ubuntu 18.04
Intel(R) Core(TM) i7-7560U CPU (2 physical + 2 virtual cores)

during successful runs, all 4 cores are uniformly utilized at about 50%. During deadlock runs, it starts the same: all 4 cores utilized at about 50% for about 5-7 seconds and then CPU usage goes virtually to 0.

the following code: ```java public static class SumKernel extends Kernel { double[] a; double[] b; double[] c; public void execute(double[] a, double[] b, double[] c) { this.a = a; this.b = b; this.c = c; execute(Range.create(a.length)); } @Override public void run() { int i = getGlobalId(); c[i] = a[i] + b[i]; globalBarrier(); } }; public static void main(String[] args) throws InterruptedException { var random = new Random(); int len = 1000_000; double[] a = new double[len]; double[] b = new double[len]; for (int i = 0; i < len; i++) { a[i] = random.nextDouble(); b[i] = random.nextDouble(); } for (int i = 0; i < 20; i++) { double[] c = new double[len]; var thread = new Thread(() -> { var kernel = new SumKernel(); kernel.setExecutionMode(EXECUTION_MODE.JTP); kernel.execute(a, b, c); kernel.dispose(); }); System.out.println(); System.out.println("starting..."); var start = System.currentTimeMillis(); thread.start(); thread.join(20_000l); if ( ! thread.isAlive()) { System.out.println("finished in " + (System.currentTimeMillis() - start)); continue; } System.out.println("still running after 20s, interrupting..."); thread.interrupt(); thread.join(2_000l); if ( ! thread.isAlive()) { System.out.println("interrupted successful."); continue; } System.out.println("still running after interrupt, stopping..."); thread.stop(); thread.join(1_000l); if (thread.isAlive()) { System.out.println("still running after stop."); } else { System.out.println("stop successful."); } } } ``` gives me an output similar to the below: > > starting... > WARNING: Aparapi is running on an untested OpenCL platform version: OpenCL 3.0 > finished in 5096 > > starting... > finished in 5069 > > starting... > finished in 4945 > > starting... > still running after 20s, interrupting... > still running after interrupt, stopping... > stop successful. > > starting... > finished in 5278 > > starting... > still running after 20s, interrupting... > still running after interrupt, stopping... > stop successful. > > starting... > finished in 5286 > > starting... > finished in 5318 > > starting... > finished in 5637 > > starting... > finished in 6113 > > starting... > finished in 6939 > > starting... > finished in 7115 > > starting... > finished in 7830 > > starting... > finished in 6700 > > starting... > finished in 6603 > > starting... > finished in 6662 > > starting... > still running after 20s, interrupting... > still running after interrupt, stopping... > stop successful. > > starting... > finished in 6820 > > starting... > finished in 6923 > > starting... > finished in 7167 It works perfectly fine on GPU (without `kernel.setExecutionMode(EXECUTION_MODE.JTP);` line) or without the `globalBarrier();` line. My environment: aparapi 3.0.0 openJDK 11 (11.0.11+9-0ubuntu2~18.04) ubuntu 18.04 Intel(R) Core(TM) i7-7560U CPU (2 physical + 2 virtual cores) during successful runs, all 4 cores are uniformly utilized at about 50%. During deadlock runs, it starts the same: all 4 cores utilized at about 50% for about 5-7 seconds and then CPU usage goes virtually to 0.

morgwai commented

2021-10-03 02:42:01 +00:00

(Migrated from git.qoto.org)

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aparapi/aparapi#8

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