NettyBlockTransferService is a storage:BlockTransferService.md that uses Netty for <
.NettyBlockTransferService, SparkEnv and BlockManager image::NettyBlockTransferService.png[align="center"]
== [[creating-instance]] Creating Instance
NettyBlockTransferService takes the following to be created:
- [[conf]] SparkConf.md[SparkConf]
- [[securityManager]] SecurityManager
- [[bindAddress]] Bind address
- [[hostName]] Host name
- [[_port]] Port number
- [[numCores]] Number of CPU cores
NettyBlockTransferService is created when SparkEnv is core:SparkEnv.md#create-NettyBlockTransferService[created] for the driver and executors (and core:SparkEnv.md#create-BlockManager[creates the BlockManager]).
== [[transportConf]][[transportContext]] TransportConf, TransportContext
NettyBlockTransferService creates a network:TransportConf.md for shuffle module (using network:SparkTransportConf.md#fromSparkConf[SparkTransportConf] utility) when <
NettyBlockTransferService uses the TransportConf for the following:
Create a network:TransportContext.md when requested to <
Create a storage:OneForOneBlockFetcher.md and a core:RetryingBlockFetcher.md[RetryingBlockFetcher] when requested to <
NettyBlockTransferService uses the TransportContext to create the <
== [[clientFactory]] TransportClientFactory
NettyBlockTransferService creates a network:TransportClientFactory.md when requested to <
NettyBlockTransferService uses the TransportClientFactory for the following:
NettyBlockTransferService requests the TransportClientFactory to network:TransportClientFactory.md#close[close] when requested to <
== [[server]] TransportServer
NettyBlockTransferService uses the TransportServer for the following:
NettyBlockTransferService requests the TransportServer to network:TransportServer.md#close[close] when requested to <
== [[port]] Port
NettyBlockTransferService simply requests the <
== [[shuffleMetrics]] Shuffle Metrics
shuffleMetrics is part of the storage:ShuffleClient.md#shuffleMetrics[ShuffleClient] abstraction.
== [[fetchBlocks]] Fetching Blocks
fetchBlocks( host: String, port: Int, execId: String, blockIds: Array[String], listener: BlockFetchingListener): Unit
When executed, fetchBlocks prints out the following TRACE message in the logs:
TRACE Fetch blocks from [host]:[port] (executor id [execId])
fetchBlocks then creates a
Depending on the maximum number of acceptable IO exceptions (such as connection timeouts) per request, if the number is greater than
0, fetchBlocks creates a core:RetryingBlockFetcher.md#creating-instance[RetryingBlockFetcher] and core:RetryingBlockFetcher.md#start[starts] it immediately.
RetryingBlockFetcher is created with the
RetryingBlockFetcher.BlockFetchStarter created earlier, the input
If however the number of retries is not greater than
0 (it could be
0 or less), the
RetryingBlockFetcher.BlockFetchStarter created earlier is started (with the input
In case of any
Exception, you should see the following ERROR message in the logs and the input
BlockFetchingListener gets notified (using
onBlockFetchFailure for every block id).
ERROR Exception while beginning fetchBlocks
fetchBlocks is part of storage:BlockTransferService.md#fetchBlocks[BlockTransferService] abstraction.
== [[appId]] Application Id
== [[close]] Closing NettyBlockTransferService
close is part of the storage:BlockTransferService.md#close[BlockTransferService] abstraction.
== [[init]] Initializing NettyBlockTransferService
init( blockDataManager: BlockDataManager): Unit
init creates a storage:NettyBlockRpcServer.md (for the SparkConf.md#getAppId[application id], a JavaSerializer and the given storage:BlockDataManager.md[BlockDataManager]) that is used to create a <
init creates the internal
clientFactory and a server.
CAUTION: FIXME What's the "a server"?
In the end, you should see the INFO message in the logs:
Server created on [hostName]:[port]
hostname is given when core:SparkEnv.md#NettyBlockTransferService[NettyBlockTransferService is created] and is controlled by spark-driver.md#spark_driver_host[
spark.driver.host Spark property] for the driver and differs per deployment environment for executors (as controlled by executor:CoarseGrainedExecutorBackend.md#main[
init is part of the storage:BlockTransferService.md#init[BlockTransferService] abstraction.
== [[uploadBlock]] Uploading Block
uploadBlock( hostname: String, port: Int, execId: String, blockId: BlockId, blockData: ManagedBuffer, level: StorageLevel, classTag: ClassTag[_]): Future[Unit]
Internally, uploadBlock creates a
TransportClient client to send a <
UploadBlock message is processed by storage:NettyBlockRpcServer.md[NettyBlockRpcServer].
UploadBlock message holds the <
blockId. It also holds the serialized bytes for block metadata with
classTag serialized (using the internal
JavaSerializer) as well as the serialized bytes for the input
blockData itself (this time however the serialization uses storage:BlockDataManager.md#ManagedBuffer[
UploadBlock message is further serialized before sending (using
CAUTION: FIXME Describe
blockId block was successfully uploaded, you should see the following TRACE message in the logs:
TRACE NettyBlockTransferService: Successfully uploaded block [blockId]
When an upload failed, you should see the following ERROR message in the logs:
ERROR Error while uploading block [blockId]
uploadBlock is part of the storage:BlockTransferService.md#uploadBlock[BlockTransferService] abstraction.
== [[UploadBlock]] UploadBlock Message
UploadBlock is a
BlockTransferMessage that describes a block being uploaded, i.e. send over the wire from a <
UploadBlock Attributes [cols="1,2",options="header",width="100%"] |=== | Attribute | Description |
appId | The application id (the block belongs to) |
execId | The executor id |
blockId | The block id |
metadata | |
blockData | The block data as an array of bytes |===
UploadBlock can calculate the encoded size and do encoding and decoding itself to or from a
== [[createServer]] createServer Internal Method
createServer( bootstraps: List[TransportServerBootstrap]): TransportServer
createServer is used when NettyBlockTransferService is requested to <
== [[logging]] Logging
ALL logging level for
org.apache.spark.network.netty.NettyBlockTransferService logger to see what happens inside.
Add the following line to
Refer to spark-logging.md[Logging].