## **4. Run Sample Applications**

After installing Hive, Hadoop and Spark successfully, we can now proceed to run some sample applications to see if they are configured appropriately.  We can use Spark Pi and Spark WordCount programs to validate our Spark installation. We can also explore how to run Spark jobs from the command line and Spark shell.

### **4.1 Spark Pi**

func TestScanRune(t *testing.T) {
	for n, test := range scanTests {
		buf := strings.NewReader(test)
		s := NewScanner(buf)
		s.Split(ScanRunes)
		var i, runeCount int
		var expect rune
		// Use a string range loop to validate the sequence of runes.
		for i, expect = range test {
			if !s.Scan() {
				break
			}
			runeCount++
			got, _ := utf8.DecodeRune(s.Bytes())
			if got != expect {

	return env.Get("MESOS_CONTAINER_NAME", "") != ""
}

// IsKubernetes returns true if minio is running in kubernetes.
func IsKubernetes() bool {
	// Kubernetes env used to validate if we are
	// indeed running inside a kubernetes pod
	// is KUBERNETES_SERVICE_HOST
	// https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/kubelet_pods.go#L541

github.com/envoyproxy/go-control-plane/ratelimit v0.1.0/go.mod h1:Wk+tMFAFbCXaJPzVVHnPgRKdUdwW/KdbRt94AzgRee4=
github.com/envoyproxy/protoc-gen-validate v1.2.1 h1:DEo3O99U8j4hBFwbJfrz9VtgcDfUKS7KJ7spH3d86P8=
github.com/envoyproxy/protoc-gen-validate v1.2.1/go.mod h1:d/C80l/jxXLdfEIhX1W2TmLfsJ31lvEjwamM4DxlWXU=
github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f h1:Y/CXytFA4m6baUTXGLOoWe4PQhGxaX0KpnayAqC48p4=

            } else {
              return Integer.compare(m1.getParameterTypes().length, m2.getParameterTypes().length);
            }
          }
        });
  }

  /** Validates that the given method's signature meets all of our assumptions. */
  private static void validateMethod(Method method) {
    String desc = method.toString();

    assertTrue(desc, isAnyEnter(method) || isWaitFor(method));

	if group == "" {
		return updatedAt, errInvalidArgument
	}

	cache := store.lock()
	defer store.unlock()

	// Validate that all members exist.
	for _, member := range members {
		u, ok := cache.iamUsersMap[member]
		if !ok {
			return updatedAt, errNoSuchUser
		}
		cr := u.Credentials

	if idx >= len(p.Pools) {
		// We don't really know if the pool is suspended or not, since it doesn't exist.
		return false
	}
	return p.Pools[idx].Decommission != nil
}

func (p *poolMeta) validate(pools []*erasureSets) (bool, error) {
	type poolInfo struct {
		position     int
		completed    bool
		decomStarted bool // started but not finished yet
	}

	rememberedPools := make(map[string]poolInfo)

    }
    assertEquals(10, CacheTesting.expirationQueueSize(cache));
    assertEquals(10, removalListener.getCount()); // these are the invalidated ones

    // old timeouts must expire after this wait
    ticker.advance(ttl * 2 / 3, MILLISECONDS);

    assertEquals(10, CacheTesting.expirationQueueSize(cache));

                    // For now, we log the action as the actual implementation
                    // depends on SmbFile's internal caching mechanism
                    log.info("Invalidated read cache for: {}", path);
                } catch (Exception e) {
                    log.error("Error invalidating read cache for path: " + path, e);
                }
            }
        }

    SmbFile[] initialFiles = dir.listFiles();
    
    // Create new file
    testFile.createNewFile();
    
    // Wait for change notification
    Thread.sleep(2000);
    
    // Cache should be invalidated, new listing should include new file
    SmbFile[] updatedFiles = dir.listFiles();
    assertEquals(initialFiles.length + 1, updatedFiles.length);
}
```

## 9. Error Handling

### 9.1 Cache Consistency