@Override
  public final void preTearDown() throws Exception {
    Host host = Host.getHost(0);
    VM vm0 = host.getVM(0);
    VM vm1 = host.getVM(1);
    vm0.invoke(PutAllGlobalDUnitTest::closeCache);
    vm1.invoke(PutAllGlobalDUnitTest::closeCache);
    cache = null;
    Invoke.invokeInEveryVM(new SerializableRunnable() {
      @Override
      public void run() {
        cache = null;
      }
    });
  }
timeout period for the put() operation, when it is run concurrent with a conflicting putAll()
operation
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/PutAllGlobalDUnitTest.java