Closing the channel returned by bind() and calling bind() again leaks native memory

[eblosug]

Each time bind() is called a new PooledByteBufAllocator is created in setBootstrapOptions().

I would expect that this allocator is released after the channel has been closed and the garbage collector has run. But the allocator still seems to be referenced. I assume that it is related to the allocator's PoolThreadLocalCache.

The PooledByteBufAllocator still keeps some arenas with chunks around, even if they are empty.