close() {
    // Mark close of pool
    this.getConnection = function getConnection() {
      return Promise.reject(new Error('ConnectionManager.getConnection was called after the connection manager was closed!'));
    };

    return this._onProcessExit();
  }
/**
   * Drain the pool and close it permanently
   *
   * @returns {Promise}
   */
Drain the pool and close it permanently
@returns {Promise}
Drain the pool and close it permanently @returns { Promise }
close() {
    this.getConnection = function getConnection() {
      return Promise.reject(new Error('ConnectionManager.getConnection was called after the connection manager was closed!'));
    };
    return this._onProcessExit();
  }
close ( ) { this . getConnection = function getConnection ( ) { return Promise . reject ( new Error ( 'ConnectionManager.getConnection was called after the connection manager was closed!' ) ) ; } ; return this . _onProcessExit ( ) ; }
Drain the pool and close it permanently
 @returns {Promise}
Drain the pool and close it permanently @returns { Promise }
// Mark close of pool