Check gradle parallel test: same process (memory) or different?

Check gradle parallel test.txt

tasks.withType<Test>().configureEach {
    maxParallelForks = 3
}

// Another File

object TestSharedObject {

    @Volatile
    var counter = 0
}

// Another File

import org.junit.Assert
import org.junit.Test

class Test1 {

    @Test
    fun t1() {
        TestSharedObject.counter = 1
        Thread.sleep(3000)
        Assert.assertEquals(1, TestSharedObject.counter)
    }
}

// Another File

import org.junit.Assert
import org.junit.Test

class Test2 {

    @Test
    fun t2() {
        TestSharedObject.counter = 2
        Thread.sleep(3000)
        Assert.assertEquals(2, TestSharedObject.counter)
    }
}

// Another File

import org.junit.Assert
import org.junit.Test

class Test3 {

    @Test
    fun t3() {
        TestSharedObject.counter = 3
        Thread.sleep(3000)
        Assert.assertEquals(3, TestSharedObject.counter)
    }
}

p.s. don't look at 9 sec, it's 3 sec in total in reality