• TL;DR
• Core changes
• Android support
• ChannelHandlerContext.attr(..) == Channel.attr(..)
• Channel.hasAttr(...)
• Easier and more precise buffer leak tracking
• PooledByteBufAllocator as the default allocator
• Globally unique channel ID
• EmbeddedChannel usability
• Ability to use Executor instead of ThreadFactory
• Class loader friendliness
• ByteBufAllocator.calculateNewCapacity()
• New codecs and handlers
• Other codec changes
• AsciiString
• TextHeaders
• MessageAggregator
• Better oversized message handling with HttpObjectAggregator
• ChunkedInput and ChunkedWriteHandler
• SnappyFramedEncoder and SnappyFramedDecoder