14158070bf
The API changes made so far turned out to increase the memory footprint
and consumption while our intention was actually decreasing them.
Memory consumption issue:
When there are many connections which does not exchange data frequently,
the old Netty 4 API spent a lot more memory than 3 because it always
allocates per-handler buffer for each connection unless otherwise
explicitly stated by a user. In a usual real world load, a client
doesn't always send requests without pausing, so the idea of having a
buffer whose life cycle if bound to the life cycle of a connection
didn't work as expected.
Memory footprint issue:
The old Netty 4 API decreased overall memory footprint by a great deal
in many cases. It was mainly because the old Netty 4 API did not
allocate a new buffer and event object for each read. Instead, it
created a new buffer for each handler in a pipeline. This works pretty
well as long as the number of handlers in a pipeline is only a few.
However, for a highly modular application with many handlers which
handles connections which lasts for relatively short period, it actually
makes the memory footprint issue much worse.
Changes:
All in all, this is about retaining all the good changes we made in 4 so
far such as better thread model and going back to the way how we dealt
with message events in 3.
To fix the memory consumption/footprint issue mentioned above, we made a
hard decision to break the backward compatibility again with the
following changes:
- Remove MessageBuf
- Merge Buf into ByteBuf
- Merge ChannelInboundByte/MessageHandler and ChannelStateHandler into ChannelInboundHandler
- Similar changes were made to the adapter classes
- Merge ChannelOutboundByte/MessageHandler and ChannelOperationHandler into ChannelOutboundHandler
- Similar changes were made to the adapter classes
- Introduce MessageList which is similar to `MessageEvent` in Netty 3
- Replace inboundBufferUpdated(ctx) with messageReceived(ctx, MessageList)
- Replace flush(ctx, promise) with write(ctx, MessageList, promise)
- Remove ByteToByteEncoder/Decoder/Codec
- Replaced by MessageToByteEncoder<ByteBuf>, ByteToMessageDecoder<ByteBuf>, and ByteMessageCodec<ByteBuf>
- Merge EmbeddedByteChannel and EmbeddedMessageChannel into EmbeddedChannel
- Add SimpleChannelInboundHandler which is sometimes more useful than
ChannelInboundHandlerAdapter
- Bring back Channel.isWritable() from Netty 3
- Add ChannelInboundHandler.channelWritabilityChanges() event
- Add RecvByteBufAllocator configuration property
- Similar to ReceiveBufferSizePredictor in Netty 3
- Some existing configuration properties such as
DatagramChannelConfig.receivePacketSize is gone now.
- Remove suspend/resumeIntermediaryDeallocation() in ByteBuf
This change would have been impossible without @normanmaurer's help. He
fixed, ported, and improved many parts of the changes.
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info
this module build will fail if any dependencies introduce osgi split package
http://wiki.osgi.org/wiki/Split_Packages
on failure, build log will show error message similar to the following:
[INFO] --- maven-bundle-plugin:2.3.7:bundle (default-bundle) @ netty-verify-osgi ---
[ERROR] Bundle io.netty:netty-verify-osgi:bundle:4.0.0.Beta1-SNAPSHOT : Split package io/netty/buffer
Use directive -split-package:=(merge-first|merge-last|error|first) on Export/Private Package instruction to get rid of this warning
Package found in [Jar:netty-buffer, Jar:netty-transport-udt]
Reference from /home/user1/.m2/repository/io/netty/netty-transport-udt/4.0.0.Beta1-SNAPSHOT/netty-transport-udt-4.0.0.Beta1-SNAPSHOT.jar
Classpath [Jar:., Jar:netty-buffer, Jar:netty-codec, Jar:netty-codec-http, Jar:netty-codec-socks, Jar:netty-common, Jar:netty-handler, Jar:netty-transport, Jar:netty-transport-rxtx, Jar:rxtx, Jar:netty-transport-sctp, Jar:netty-transport-udt, Jar:barchart-udt-bundle]
[ERROR] Error(s) found in bundle configuration