flume报错了ERROR RPC client creation failed! NettyAvroRpcClient

Question

flume中设置了监听端口：

agent.sources.log4j.type = avro
agent.sources.log4j.bind = 0.0.0.0
agent.sources.log4j.port = 4450

安全组已经开放了4450端口
但是用java发送的时候还是报错了：

log4j:ERROR RPC client creation failed! NettyAvroRpcClient { host: , port: 4450 }: RPC connection error
SLF4J: A number (7) of logging calls during the initialization phase have been intercepted and are
SLF4J: now being replayed. These are subject to the filtering rules of the underlying logging system.

flume的配置是：

log4j.appender.flume.Hostname =X.X.X.X
log4j.appender.flume.Port = 4450
log4j.appender.flume.UnsafeMode = true