log4j.logger.org.apache.spark.network.netty.NettyBlockRpcServer=TRACE
NettyBlockRpcServer
NettyBlockRpcServer
is a RpcHandler
(i.e. a handler for sendRPC()
messages sent by TransportClient
s) that handles BlockTransferMessage
messages for NettyBlockTransferService.
NettyBlockRpcServer
uses OneForOneStreamManager as the internal StreamManager
.
Message | Behaviour |
---|---|
Obtaining local blocks and registering them with the internal OneForOneStreamManager. |
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Deserializes a block and stores it in BlockDataManager. |
Tip
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Enable TRACE logging level to see received messages in the logs.
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Tip
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Enable Add the following line to Refer to Logging. |
Creating NettyBlockRpcServer Instance
class NettyBlockRpcServer(
appId: String,
serializer: Serializer,
blockManager: BlockDataManager)
extends RpcHandler
When created, NettyBlockRpcServer
gets the application id (appId
) and a Serializer
and a BlockDataManager.
Note
|
NettyBlockRpcServer is created when NettyBlockTransferService is initialized.
|
NettyBlockRpcServer
merely creates the internal instance of OneForOneStreamManager.
Note
|
As a RpcHandler , NettyBlockRpcServer uses the OneForOneStreamManager for getStreamManager (which is a part of the RpcHandler contract).
|
Obtaining Local Blocks and Registering with Internal OneForOneStreamManager
— OpenBlocks
Message Handler
When OpenBlocks
arrives, NettyBlockRpcServer
requests block data (from BlockDataManager
) for every block id in the message. The block data is a collection of ManagedBuffer
for every block id in the incoming message.
Note
|
BlockDataManager is given when NettyBlockRpcServer is created.
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NettyBlockRpcServer
then registers a stream of ManagedBuffer
s (for the blocks) with the internal StreamManager
under streamId
.
Note
|
The internal StreamManager is OneForOneStreamManager and is created when NettyBlockRpcServer is created.
|
You should see the following TRACE message in the logs:
TRACE NettyBlockRpcServer: Registered streamId [streamId] with [size] buffers
In the end, NettyBlockRpcServer
responds with a StreamHandle
(with the streamId
and the number of blocks). The response is serialized as a ByteBuffer
.
Deserializing Block and Storing in BlockDataManager
— UploadBlock
Message Handler
When UploadBlock
arrives, NettyBlockRpcServer
deserializes the metadata
of the input message to get the StorageLevel and ClassTag
of the block being uploaded.
Note
|
metadata is serialized before NettyBlockTransferService sends a UploadBlock message (using the internal JavaSerializer ) that is given as serializer when NettyBlockRpcServer is created.
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NettyBlockRpcServer
creates a BlockId
for the block id and requests the BlockDataManager
to store the block.
Note
|
The BlockDataManager is passed in when NettyBlockRpcServer is created.
|
In the end, NettyBlockRpcServer
responds with a 0
-capacity ByteBuffer
.
Note
|
UploadBlock is sent when NettyBlockTransferService uploads a block.
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