private ConcurrentMap<String, Object> getRequestSharedDataContext(long requestId) {
    synchronized (requestSharedDataMap) {
      ConcurrentMap<String, Object> map = requestSharedDataMap.get(requestId);

      if (map == null) {
        map = new ConcurrentHashMap<>();
        requestSharedDataMap.put(requestId, map);
      }

      return map;
    }
  }
Returns a Map to be used to share data among server actions within a given request context.

@param requestId a long identifying the id of the relevant request
@return a ConcurrentMap of "shared" data
ambari-server/src/main/java/org/apache/ambari/server/serveraction/ServerActionExecutor.java