Akka 发布了 2.1 的首个维护版本 2.1.1，该版本更新了文档，同时修复了以下 bug：

• release thread pool used by Netty’s ExecutionHandler more timely
• passive remote connections now work when using secure cookies
• do not silently swallow exceptions in ForkJoinPool executor anymore
• fix a bug in HashedWheelTimer which would schedule events incorrectly if delay is multiple of one wheel rotation (thanks Matthew Neeley)
• fix reporting of error condition when IOManager binds to a port
• make sure to set Thread.interrupt() flag when catching InterruptedException during tell()
• Netty does not close the connection anymore upon encountering a non-serializable or too large message
• PinnedDispatcher does not allow its thread to time out anymore, keeping the actor on the same thread (as opposed to only on its own thread)
• actually disallow sending `null` messages (was always forbidden by documentation and only worked on some special ActorRefs)
• StdoutLogger restores stdout-loglevel during system shutdown
• do not leak the default dispatcher anymore
• do not set SO_REUSEADDR for remoting on Windows (which implements this in a buggy way)
• properly log exceptions without a message in JulEventLogger (thanks Sam Halliday)

此外在集群模块上还包含如下改动：

• cluster metric-aware adaptive load balancing routers
• automatically load cluster extension when used, no need to declare in `akka.extensions` anymore
• fire DeathWatch only upon member DOWN, not already at UNREACHABLE
• allow configuration of minimum number of members before starting the cluster
• cluster singleton pattern
• detect failure even when no heartbeat was ever sent

详情请看官方发行说明。