Hi Azat, Thanks for your reply.Yes, i'm using the bufferevent ssl API. I will give the latest libevent a try.Sorry for can't providing a sample, but I can describe the scenario:After connect with Apple's APNS server, send data as fast as i can, and most of time Apns server don't reply with a response.however, under certain condition, the Apns server will send back a response, Âversion of libevent-2.0.22-stableÂcan't catch up the response sometimes. Hope this helps.--Anty Rao