recover capacity check

paddle/fluid/distributed/service/communicator.h

@@ -61,7 +61,11 @@ using Variable = framework::Variable;
 template <typename T>
 class BlockingQueue {
  public:
-  explicit BlockingQueue(size_t capacity) : capacity_(capacity) {}
+  explicit BlockingQueue(size_t capacity) : capacity_(capacity) {
+    PADDLE_ENFORCE_GT(capacity_, 0,
+                      platform::errors::InvalidArgument(
+                          "The capacity must be greater than 0."));
+  }
 
   bool Push(const T &elem) {
     std::unique_lock<std::mutex> lock(mutex_);