@Test
  public void testConcurrentOperations() {

    // create the VM(0 - 4)
    for (int i = 0; i < 4; i++) {
      VM vm = VM.getVM(i);
      vm.invoke("createRegion", () -> {
        Cache cache1 = getCache();
        RegionAttributes<?, ?> regionAttribs = getRegionAttributes();
        cache1.createRegionFactory(regionAttribs).create("R1");
      });
    }

    concurrentMapTest(SEPARATOR + "R1");
  }
This is a for the ConcurrentMap operations. 4 VMs are used to create the region and operations
are performed on one of the nodes
geode-dunit/src/main/java/org/apache/geode/cache30/MultiVMRegionTestCase.java