the site documentation states: "In particular, in the extreme case where the network link to the server is down, the client will be eventually blocked."

this does not reflect the actual implementation. the socket appender uses a queue internally, which uses the time-out-based offer method when adding events to the queue. so actually the socket appender is not expected to block. however it is expected to get slower (100 ms waits on offer) when the queue producer is faster than the consumer and the queue reaches its size limit.