TestParallelAlwaysPreTouch.java

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package gc.g1;

/*
 * @test
 * @bug 8169703
 * @summary Regression test to ensure AlwaysPreTouch with multiple threads works at mutator time.
 * Allocates a few humongous objects that will be allocated by expanding the heap, causing concurrent parallel
 * pre-touch.
 * @requires vm.gc.G1
 * @run main/othervm -XX:+UseG1GC -Xms10M -Xmx100m -XX:G1HeapRegionSize=1M -XX:+AlwaysPreTouch -XX:PreTouchParallelChunkSize=512k -Xlog:gc+ergo+heap=debug,gc+heap=debug,gc=debug gc.g1.TestParallelAlwaysPreTouch
 */

public class TestParallelAlwaysPreTouch {
    public static void main(String[] args) throws Exception {
        final int M = 1024 * 1024; // Something guaranteed to be larger than a region to be counted as humongous.

        for (int i = 0; i < 10; i++) {
            Object[] obj = new Object[M];
            System.out.println(obj);
        }
    }
}