如何停止超时的DB查询-CFANZ编程社区

一.问题:有时我们执行的DB查询(例如一些查询的存储过程)会时间太长,当我们的代码逻辑上不想等待这么长时间时,怎么删除呢?

二.思考:首先想到使用"select connectionId()",然后通过"kill query id"语句来删除掉对应的DB进程.后来发现JdbcTemplate里面CallableStatement的cancel()可以关掉存储过程的调用.那么我们可以结合Timer来计时,当超过N分钟后,就执行cancel()即可.

三.代码:

1.定义一个task:(可以配合connectionId来做追踪,虽然逻辑上没有使用上)

public class CustomTimeTask extends TimerTask {
  private static final Logger logger = LoggerFactory.getLogger(CustomTimeTask.class);
  
  CallableStatement cs ;
  int id;
  
  public CustomTimeTask(CallableStatement cs, int id) {
    super();
    this.cs = cs;
    this.id = id;
  }

  @Override
  public void run() {
    try {
      logger.info("[Timeout]TimeTask try to cancel the long time procedure query. Connection ID is [{}]", id);
      cs.cancel();
    } catch (Exception e) {
      logger.error("[Timeout]TimeTask fail to cancel the long time procedure query. Please check the if the query has been stopped in database. "
          + "The connection ID is [{}]", id);
    }
  }

}

2.执行:

logger.debug("-----------Start to call CSV store procedure------------");
    Connection conn = null;
    CallableStatement cs = null;
    ResultSet rs = null;
    
    Timer timer = null;
    boolean isQuery = false;
    
  ......
    try{
      conn = jdbcTemplate.getDataSource().getConnection();
      cs = conn.prepareCall(foo);
      ....
      
      isQuery = true;
      int queryTimeoutMins = SystemConfig.getQueryTimeout();
      if(queryTimeoutMins>0) {
        logger.debug("Execute the statemnet to call procedure  to connection ID [{}]. "
          + "And start the timer to cancel the timeout query. Timeout setting [{} minutes]"
            ,conID,queryTimeoutMins);
        CustomTimeTask customTimeTask = new CustomTimeTask(cs, conID);
        timer = new Timer();
        timer.schedule(customTimeTask, queryTimeoutMins * 60 * 1000);
      }else {
        logger.debug("Execute the statemnet to call procedure to gen CSV record to connection ID [{}]. "
            + "But not start the timer to cancel the timeout query because timeout setting is [{} minutes]"
            ,conID,queryTimeoutMins);
      }
      
      cs.execute();
      if(timer != null) {
        logger.debug("The query for connection ID [{}] is completed. "
          + "Cancel the timer and begin to get the resultSet. ",conID);
        timer.cancel();
        timer.purge();
      }else {
        logger.debug("The query for connection ID [{}] is completed. Begin to get the resultSet.",conID);
      }
      isQuery = false;
      
      rs = cs.getResultSet();
      
      .........
      
      ...........
      
      rs.close();
    }catch (DataAccessException e) {
      dbLogger.error("DB is down. Exception is [{}]", e.getMessage());
      try {
        if(isQuery && cs!=null && !cs.isClosed()) {
          logger.info("Program has begun the query. Try to cancel the procedure query for connection ID [{}]"
              , conID);
          cs.cancel();
        }
        
      } catch (MySQLStatementCancelledException e1) {
        logger.info("Successfully cancel the procedure query for connection ID [{}]"
            , conID);
        if(timer != null) {
          timer.cancel();
          timer.purge();
        }
        isQuery = false;
      } catch (Exception e1) {
        logger.error("-- Error occur when try to cancel the query for connection ID[{}]. "
            + "Exception is [{}].",conID, e.getMessage());
      }
      throw e;
      
    } catch (MySQLStatementCancelledException e) {
      logger.info("Successfully cancel the procedure query for connection ID [{}]"
          , conID);
      if(timer != null) {
        timer.cancel();
        timer.purge();
      }
      isQuery = false;
      return null;
    }catch (Exception e) {
      logger.error("-- Error occur, exception is [{}]", e.getMessage());
      logger.error("DB: error:", e);
      try {
        if(isQuery && cs!=null && !cs.isClosed()) {
          logger.info("Program has begun the query. Try to cancel the procedure query for connection ID [{}]"
              , conID);
          cs.cancel();
        }
        
      } catch (MySQLStatementCancelledException e1) {
        logger.info("Successfully cancel the procedure query for connection ID [{}]"
            , conID);
        if(timer != null) {
          timer.cancel();
          timer.purge();
        }
        isQuery = false;
      } catch (Exception e1) {
        logger.error("-- Error occur when try to cancel the query for connection ID[{}]. "
            + "Exception is [{}].",conID, e.getMessage());
      }
      
      return null;
    }finally {
      try {
        if (rs != null)
          rs.close();
        if (cs != null)
          cs.close();
        if (conn != null) {
          conn.close();
        }
      } catch (Exception e) {
        logger.error("Error occurs when close the connection to database. Error:", e);
        return null;
      }
      
    }
    logger.debug("-----------End to call store procedure------------");
    return resultMap;
  }