Crash if first sysout happens from other thread than runner thread

[Haspamelodica]

See title.

PoC with plain threads

package net.haspamelodica.aresexperiments.tests;

import static org.junit.jupiter.api.Assertions.assertEquals;

import de.tum.in.test.api.ActivateHiddenBefore;
import de.tum.in.test.api.AllowThreads;
import de.tum.in.test.api.BlacklistPath;
import de.tum.in.test.api.Deadline;
import de.tum.in.test.api.MirrorOutput;
import de.tum.in.test.api.PathType;
import de.tum.in.test.api.StrictTimeout;
import de.tum.in.test.api.WhitelistPath;
import de.tum.in.test.api.jupiter.PublicTest;
import net.haspamelodica.aresexperiments.ExampleTestee;

@MirrorOutput
@StrictTimeout(10000)
@Deadline("2021-11-15 05:30 Europe/Berlin")
@ActivateHiddenBefore("2021-11-05 16:30 Europe/Berlin")
//@WhitelistPath(value = "../pgdp2122*w03h01**", type = PathType.GLOB) // for manual assessment and development
@WhitelistPath("target") // mainly for Artemis
@BlacklistPath(value = "{src,target}**Test*.{java,class}", type = PathType.GLOB)
@AllowThreads
public class ExampleTest
{
	@PublicTest
	public void insecureTest()
	{
		assertEquals(1337, new ExampleTestee().getSecretNumber());
	}
}

package net.haspamelodica.aresexperiments;

public class ExampleTestee
{
	public long getSecretNumber()
	{
		//System.out.println("some output");

		Thread thread = new Thread(() -> System.out.println("asdf"));
		thread.start();
		try
		{
			thread.join();
		} catch(InterruptedException e)
		{
			throw new RuntimeException(e);
		}

		return 123;
	}
}

This also happens from the CommonPool and crashes regardless of AllowThreads:

PoC with CommonPool

package net.haspamelodica.aresexperiments.tests;

import static org.junit.jupiter.api.Assertions.assertEquals;

import de.tum.in.test.api.ActivateHiddenBefore;
import de.tum.in.test.api.BlacklistPath;
import de.tum.in.test.api.Deadline;
import de.tum.in.test.api.MirrorOutput;
import de.tum.in.test.api.PathType;
import de.tum.in.test.api.StrictTimeout;
import de.tum.in.test.api.WhitelistPath;
import de.tum.in.test.api.jupiter.PublicTest;
import net.haspamelodica.aresexperiments.ExampleTestee;

@MirrorOutput
@StrictTimeout(10000)
@Deadline("2021-11-15 05:30 Europe/Berlin")
@ActivateHiddenBefore("2021-11-05 16:30 Europe/Berlin")
//@WhitelistPath(value = "../pgdp2122*w03h01**", type = PathType.GLOB) // for manual assessment and development
@WhitelistPath("target") // mainly for Artemis
@BlacklistPath(value = "{src,target}**Test*.{java,class}", type = PathType.GLOB)
public class ExampleTest
{
	@PublicTest
	public void insecureTest()
	{
		assertEquals(1337, new ExampleTestee().getSecretNumber());
	}
}

package net.haspamelodica.aresexperiments;

import java.util.concurrent.atomic.AtomicBoolean;
import java.util.stream.IntStream;

public class ExampleTestee
{
	public long getSecretNumber()
	{
		//System.out.println("some output");

		Thread forbiddenThread = Thread.currentThread();
		AtomicBoolean firstOtherThread = new AtomicBoolean(true);
		IntStream
				.range(0, 100)
				.parallel()
				.forEach(i ->
				{
					if(Thread.currentThread() == forbiddenThread)
						return;
					if(!firstOtherThread.getAndSet(false))
						return;
					System.out.println("sysout from other thread");
				});

		return 123;
	}
}

[Haspamelodica]

The core exception is thrown in OutputTester#acceptOutput line 56

[MaisiKoleni]

Probably something related to the lambda creation, not visible in the Java sources.