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
();
}
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