jediscluster的maxAttempts的理解

1.我们知道进行redis配置的时候可以配置maxAttempts参数，那么这个参数的含义是什么呢？
} catch (JedisNoReachableClusterNodeException jnrcne) { throw jnrcne; } catch
(JedisConnectionException jce) { // release current connection before recursion
releaseConnection(connection); connection = null; if (attempts <= 1) { //We
need this because if node is not reachable anymore - we need to finally
initiate slots //renewing, or we can stuck with cluster state without one node
in opposite case. //But now if maxAttempts = [1 or 2] we will do it too often.
//TODO make tracking of successful/unsuccessful operations for node - do
renewing only //if there were no successful responses from this node last few
seconds this.connectionHandler.renewSlotCache(); } return runWithRetries(slot,
attempts - 1, tryRandomNode, redirect); }`
最核心的代码是catch(JedisConnectionException) 异常的时候回进行重试指定的次数。

2.问题来了，什么情况下会抛出JedisConnectionException呢？连接超时或者读取超时会导致这个异常吗？是仅仅连接超时才会重试，还是连接超时或者读取超时都会重试？
private static void sendCommand(final RedisOutputStream os, final byte[]
command, final byte[]... args) { try { os.write(ASTERISK_BYTE); os.writeIntCrLf(
args.length + 1); os.write(DOLLAR_BYTE); os.writeIntCrLf(command.length); os.
write(command); os.writeCrLf(); for (final byte[] arg : args) { os.write(
DOLLAR_BYTE); os.writeIntCrLf(arg.length); os.write(arg); os.writeCrLf(); } }
catch (IOException e) { throw new JedisConnectionException(e); } }

可以看到向redis发送命令的代码，只要是IOException的时候redis都会转成JedisConnectionException向上抛出，所以可以知道，不管是连接超时ConnectionException还是读取超时SocketTimeOutException，都会进行重试，而重试的次数就是MaxAttempts参数指定的

• « 上一篇：开发人员谈测试：做好软件测试才能提升应用质量
• » 下一篇：华为初面+综合面试（Java技术面