JedisDataException: Please close pipeline or multi block before calling this method

错误原因

transaction错误使用

pipeline错误使用


具体分析

transaction错误使用

  • Redis事务的执行结果是在exec之后才统一返回,所以Jedis会用一个Response对象最为事务对象transaction的执行放回值。如果我们在transaction执行exec方法之前调用response对象的get方法会出现异常:
  • Exception in thread "main" redis.clients.jedis.exceptions.JedisDataException: Please close pipeline or multi block before calling this method.
  • 更多Redis事务操作,请移步:https://blog.csdn.net/fly910905/article/details/78981084
pipeline错误使用

1.异常堆栈

redis.clients.jedis.exceptions.JedisDataException: Please close pipeline or multi block before calling this method.

2.异常描述:

在pipeline.sync()执行之前,通过response.get()获取值,在pipeline.sync()执行前,命令没有执行(可以通过monitor做验证),下面代码就会引起上述异常

Jedis jedis = new Jedis("127.0.0.1", 6379);
Pipeline pipeline = jedis.pipelined();
pipeline.set("hello", "world"); 
pipeline.set("java", "jedis");
    
Response pipeString = pipeline.get("java");
//这个get必须在sync之后,如果是批量获取值建议直接用List objectList = pipeline.syncAndReturnAll();
System.out.println(pipeString.get());
//命令此时真正执行
pipeline.sync(); 
  

Jedis中Reponse中get()方法,有个判断:如果set=false就会报错,而response中的set初始化为false.

public T get() {
  // if response has dependency response and dependency is not built,
  // build it first and no more!!
  if (dependency != null && dependency.set && !dependency.built) {
    dependency.build();
  }
  if (!set) {
    throw new JedisDataException(
        "Please close pipeline or multi block before calling this method.");
  }
  if (!built) {
    build();
  }
  if (exception != null) {
    throw exception;
  }
  return response;
}

pipeline.sync()会每个结果设置set=true。

public void sync() {
  if (getPipelinedResponseLength() > 0) {
    List unformatted = client.getAll();
    for (Object o : unformatted) {
      generateResponse(o);
    }
  }
} 
  

其中generateResponse(o):

protected Response> generateResponse(Object data) {
  Response> response = pipelinedResponses.poll();
  if (response != null) {
    response.set(data);
  }
  return response;
}

其中response.set(data);

public void set(Object data) {
    this.data = data;
    set = true;
}

3.解决方法:

实际上对于批量结果的解析,建议使用pipeline.syncAndReturnAll()来实现,下面操作模拟了批量hgetAll


/**
* pipeline模拟批量hgetAll
* @param keyList
* @return
*/
public Map<String, Map<String, String>> mHgetAll(List<String> keyList) {
// 1.生成pipeline对象
Pipeline pipeline = jedis.pipelined();
// 2.pipeline执行命令,注意此时命令并未真正执行
for (String key : keyList) {
  pipeline.hgetAll(key);
}
// 3.执行命令 syncAndReturnAll()返回结果
List<Object> objectList = pipeline.syncAndReturnAll();
if (objectList == null || objectList.isEmpty()) {
  return Collections.emptyMap();
}
    
// 4.解析结果
Map<String,Map<String, String>> resultMap = new HashMap<String, Map<String,String>>();
for (int i = 0; i < objectList.size(); i++) {
  Object object = objectList.get(i);
  Map<String, String> map = (Map<String, String>) object;
  String key = keyList.get(i);
  resultMap.put(key, map);
}
return resultMap;
}

4.处理人:

修改业务代码。


参考来源:https://yq.aliyun.com/articles/236384?spm=a2c4e.11155435.0.0.e21e2612uQAVoW#cc1

你可能感兴趣的:(Redis,Redis:不只是数据库)