Yii2 随机发生 php mongo报错：’Failed to connect to: XXXXX: Remote server has closed the connection’的解决方法

运行mongodb连接的时候，遇到了 Remote server has closed the connection 的错误问题。而且是随机性发生的。

在Yii2中，需要进行的修改为：

Yii2-mongodb/Connecting.php

修改函数：

public function open()
   {
       if ($this->mongoClient === null) {
           if (empty($this->dsn)) {
               throw new InvalidConfigException($this->className() . '::dsn cannot be empty.');
           }
           $token = 'Opening MongoDB connection: ' . $this->dsn;
           try {
               Yii::trace($token, __METHOD__);
               Yii::beginProfile($token, __METHOD__);
               $options = $this->options;
               $options['connect'] = true;
               if ($this->defaultDatabaseName !== null) {
                   $options['db'] = $this->defaultDatabaseName;
               }
              // $this->mongoClient = new \MongoClient($this->dsn, $options);
         $this->mongoClient = $this->getCustomMongoClient($options);
               $this->initConnection();
               Yii::endProfile($token, __METHOD__);
           } catch (\Exception $e) {
               Yii::endProfile($token, __METHOD__);
               throw new Exception($e->getMessage(), (int) $e->getCode(), $e);
           }
       }
   }

添加函数

public function getCustomMongoClient($options,$retry = 4) {
    try {
      return new \MongoClient($this->dsn, $options);
    } catch(Exception $e) {
      /* Log the exception so we can look into why mongod failed later */
      //logException($e);
    }
    if ($retry > 0) {
      return $this->getCustomMongoClient($options, --$retry);
    }
    throw new Exception("I've tried several times getting MongoClient.. Is mongod really running?");
  }

也就是通过多次尝试连接的方式。