netty can learn not only the network library also includes threading model, how to write java asynchronous interaction, custom cache model for the clever use of pool management, internal class of direct memory, good design patterns, as well as some rare network Thinking cross-platform bug processing communication.
Note:
Outer heap memory: GC heap susceptible to the influence due to the influence GC results lead to the memory address changes, memory leaks and difficulty in programming model asynchronous transmission network
1, the heap memory: fast, but limited capacity.
2, outside the reactor (OffHeapStore) Storage: is called BigMemory, only available in the Enterprise version of Ehcache, the principle is the use of nio DirectByteBuffers achieve, faster than disk storage to, and totally unaffected by GC, you can ensure a response time stability; however, the overhead on the direct buffer allocated heap buffer than large, and requires to be stored in the byte array embodiment, the object must be serialized during storage, the read operation is deserialized, it the speed ratio of about one order of magnitude slower heap memory.
(Note: direct buffer not affect the GC, but direct buffer belongs JAVA object on the heap and can be recovered GC, once it has been recovered, the JVM will release the direct buffer heap outer space.) "