問題現象

棧溢出（不斷的重連）

		at redis.clients.jedis.Connection.sendCommand(Connection.java:163)at redis.clients.jedis.Connection.sendCommand(Connection.java:154)at redis.clients.jedis.BinaryClient.auth(BinaryClient.java:815)at redis.clients.jedis.BinaryClient.connect(BinaryClient.java:145)at redis.clients.jedis.Connection.sendCommand(Connection.java:163)at redis.clients.jedis.Connection.sendCommand(Connection.java:154)at redis.clients.jedis.BinaryClient.auth(BinaryClient.java:815)at redis.clients.jedis.BinaryClient.connect(BinaryClient.java:145)

讀取超時

未知響應

嘗試讀取損壞的鏈接

讀取到的數據和自己要讀的無關，導致空指針、類型轉換錯誤，數據讀取錯亂

問題寫法

對Redis操作封裝了一個Redis類

同事對pipeline加了這個方法

使用的時候

   public Map<String, AnswerModel> batchGetAnswersPipeline(List<String> answerIdList) {Map<String, AnswerModel> resultMap = new HashMap<>();try (Pipeline pipelined = redis.pipelined()) {List<Response<Map<String, String>>> responses = new ArrayList<>();for (String answerId : answerIdList) {String key = String.format(MOMENT_ANSWER_INFO, answerId);responses.add(pipelined.hgetAll(key));}pipelined.sync();for (Response<Map<String, String>> response : responses) {Map<String, String> map = response.get();AnswerModel answers = BeanUtil.mapToBean(map, AnswerModel.class);if (answers != null){resultMap.put(answers.getAnswerId(), answers);}}} catch (Exception e) {log.error("執行batchGetAnswersPipeline發生異常, redis pipeline error", e);throw new CatVillageException();}return resultMap;}

問題分析

在redis這個工具類中調pipelined時獲取一個Pinelined對象，而獲取這個方法里用了try with ，with了一個jedis鏈接，當try結束時鏈接會被歸還jedispool連接池。而返回的這個pipeline仍然在用這個鏈接，當其他線程去拿鏈接的時候可能拿到的正好是這個鏈接，導致多個線程共用一個鏈接，一個線程在執行pipeline多條命令，另一個線程也在用這個鏈接。而jedis底層執行命令的時候是使用的OutputStream流式去執行命令，使用二進制流讀取結果。當出現這種線程不安全問題的時候，讀取寫入就會有問題。

修復

刪除Redis工具類中的pipelined方法，使用getJedis方法獲取鏈接對象，再獲取管道Pineline對象,自行close管道，最后執行完釋放管道，鏈接。

public Map<String, QuestionModel> batchGetQuestionPipeline(List<String> questionIdList) {if (CollectionUtils.isEmpty(questionIdList)){return new HashMap<>();}Map<String, QuestionModel> resultMap = new HashMap<>();try (Jedis jedis = redis.getJedis()) {Pipeline pipelined = jedis.pipelined();List<Response<Map<String, String>>> responses = new ArrayList<>();for (String questionId : questionIdList) {String key = String.format(MOMENT_QUESTION_INFO, questionId);responses.add(pipelined.hgetAll(key));}pipelined.sync();for (Response<Map<String, String>> response : responses) {Map<String, String> map = response.get();QuestionModel question = convertFromMap(map);if (question != null) {resultMap.put(question.getPostId(), question);}}pipelined.close();} catch (Exception e) {log.error("執行batchGetQuestionPipeline發生異常, redis pipeline error", e);throw new CatVillageException();}return resultMap;}

注意點

若jedis在3.7版本以下的版本也會有管道二進制讀取異常問題，請升級到3.7.0+版本