Netty 3 makes use of ExecutionHandler which gives the ability to configure the system by passing in an Executor. For example an OrderedMemoryAwareThreadPoolExecutor can be used which allows ability to configure things like corePoolSize, maxChannelMemorySize, maxTotalMemorySize etc.
In Netty 4, ExecutionHandler has been removed In New and noteworthy in 4.0 it is mentioned to use DefaultEventExecutor but as far as I can see, this does not have the same level of configuration flexibility as the removed ExecutionHandler.
The question is how do one configure EventExecutor in Netty 4 like ExecutionHandler in Netty 3?
In Netty 4 an event executor is assigned when a handler is added to the channel pipeline. For example:
https://netty.io/4.1/api/io/netty/channel/ChannelPipeline.html#addLast-io.netty.util.concurrent.EventExecutorGroup-java.lang.String-io.netty.channel.ChannelHandler-