protected void closeRegion(VM vm, final String regionName) {
    SerializableRunnable close = new SerializableRunnable() {
      @Override
      public void run() {
        Cache cache = getCache();
        Region region = cache.getRegion(regionName);
        region.close();
      }
    };

    vm.invoke(close);
  }
Test for 43551. Do a shutdown all with some members waiting on recovery.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/partitioned/ShutdownAllDUnitTest.java