Connection.isConnected() falsly returns true after network disconnect/reconnect

When I connect to the Redis instance with Jedis and then disable ethernet adapter in windows and reanable it, isConnected() method will return true, when in reality it is not and all redis commands like ping, lpush, etc. will throw java.net.SocketException.

Caused by: java.net.SocketException: Connection reset by peer: socket write error
    at java.net.SocketOutputStream.socketWrite0(Native Method)
    at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:109)
    at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
    at redis.clients.util.RedisOutputStream.flushBuffer(RedisOutputStream.java:31)
    at redis.clients.util.RedisOutputStream.flush(RedisOutputStream.java:223)
    at redis.clients.jedis.Connection.flush(Connection.java:276)
    ... 11 more

[defnull]

Welcome to the joys of network programming: The only way to find out if you can send data over a socket, is sending data over a socket. This is true for any networking library, not just Jedis.

isConnected() == false tells you that the client needs to reconnect (which it does automatically). isConnected() == true does not tell you anything. The next command might get through, or it might not. Even if the TCP stream is perfectly fine and healthy at the time you call isConnected() or ping(), network might go down the millisecond after. You ALWAYS have to expect commands to fail. Checking isConnected() beforehand is useless.

That said, isConnected() will only lie to you if the socket is in an undefined state (disconnected, but the operating system does not know that yet). It returns true if the socket appear to be connected. That’s fair, I think.

[galsivan]

It still doesn’t make a lot of sense because it is not really connected. Normally an isConnected() function checks that a connection is still alive, not that the object is initialized or resources are present. The name is misleading since the function returns true when the connection is dead and redis is down. I think maybe something like isInitialized() would make more sense. Just my two cents.