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BlockManagerMasterEndpoint

= BlockManagerMasterEndpoint -- BlockManagerMaster RPC Endpoint :navtitle: BlockManagerMasterEndpoint

BlockManagerMasterEndpoint is a rpc:RpcEndpoint.md#ThreadSafeRpcEndpoint[ThreadSafeRpcEndpoint] for storage:BlockManagerMaster.md[BlockManagerMaster].

BlockManagerMasterEndpoint is registered under BlockManagerMaster name.

BlockManagerMasterEndpoint tracks status of the storage:BlockManager.md[BlockManagers] (on the executors) in a Spark application.

== [[creating-instance]] Creating Instance

BlockManagerMasterEndpoint takes the following to be created:

  • [[rpcEnv]] rpc:RpcEnv.md[]
  • [[isLocal]] Flag whether BlockManagerMasterEndpoint works in local or cluster mode
  • [[conf]] ROOT:SparkConf.md[]
  • [[listenerBus]] scheduler:LiveListenerBus.md[]

BlockManagerMasterEndpoint is created for the core:SparkEnv.md#create[SparkEnv] on the driver (to create a storage:BlockManagerMaster.md[] for a storage:BlockManager.md#master[BlockManager]).

When created, BlockManagerMasterEndpoint prints out the following INFO message to the logs:

[source,plaintext]

BlockManagerMasterEndpoint up

== [[messages]][[receiveAndReply]] Messages

As an rpc:RpcEndpoint.md[], BlockManagerMasterEndpoint handles RPC messages.

=== [[BlockManagerHeartbeat]] BlockManagerHeartbeat

[source, scala]

BlockManagerHeartbeat( blockManagerId: BlockManagerId)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[GetLocations]] GetLocations

[source, scala]

GetLocations( blockId: BlockId)


When received, BlockManagerMasterEndpoint replies with the <> of blockId.

Posted when BlockManagerMaster.md#getLocations-block[BlockManagerMaster requests the block locations of a single block].

=== [[GetLocationsAndStatus]] GetLocationsAndStatus

[source, scala]

GetLocationsAndStatus( blockId: BlockId)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[GetLocationsMultipleBlockIds]] GetLocationsMultipleBlockIds

[source, scala]

GetLocationsMultipleBlockIds( blockIds: Array[BlockId])


When received, BlockManagerMasterEndpoint replies with the <> for the given storage:BlockId.md[].

Posted when BlockManagerMaster.md#getLocations[BlockManagerMaster requests the block locations for multiple blocks].

=== [[GetPeers]] GetPeers

[source, scala]

GetPeers( blockManagerId: BlockManagerId)


When received, BlockManagerMasterEndpoint replies with the <> of blockManagerId.

Peers of a storage:BlockManager.md[BlockManager] are the other BlockManagers in a cluster (except the driver's BlockManager). Peers are used to know the available executors in a Spark application.

Posted when BlockManagerMaster.md#getPeers[BlockManagerMaster requests the peers of a BlockManager].

=== [[GetExecutorEndpointRef]] GetExecutorEndpointRef

[source, scala]

GetExecutorEndpointRef( executorId: String)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[GetMemoryStatus]] GetMemoryStatus

[source, scala]

GetMemoryStatus

When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[GetStorageStatus]] GetStorageStatus

[source, scala]

GetStorageStatus

When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[GetBlockStatus]] GetBlockStatus

[source, scala]

GetBlockStatus( blockId: BlockId, askSlaves: Boolean = true)


When received, BlockManagerMasterEndpoint is requested to <>.

Posted when...FIXME

=== [[GetMatchingBlockIds]] GetMatchingBlockIds

[source, scala]

GetMatchingBlockIds( filter: BlockId => Boolean, askSlaves: Boolean = true)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[HasCachedBlocks]] HasCachedBlocks

[source, scala]

HasCachedBlocks( executorId: String)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[RegisterBlockManager]] RegisterBlockManager

[source,scala]

RegisterBlockManager( blockManagerId: BlockManagerId, maxOnHeapMemSize: Long, maxOffHeapMemSize: Long, sender: RpcEndpointRef)


When received, BlockManagerMasterEndpoint is requested to <> (by the given storage:BlockManagerId.md[]).

Posted when BlockManagerMaster is requested to storage:BlockManagerMaster.md#registerBlockManager[register a BlockManager]

=== [[RemoveRdd]] RemoveRdd

[source, scala]

RemoveRdd( rddId: Int)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[RemoveShuffle]] RemoveShuffle

[source, scala]

RemoveShuffle( shuffleId: Int)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[RemoveBroadcast]] RemoveBroadcast

[source, scala]

RemoveBroadcast( broadcastId: Long, removeFromDriver: Boolean = true)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[RemoveBlock]] RemoveBlock

[source, scala]

RemoveBlock( blockId: BlockId)


When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[RemoveExecutor]] RemoveExecutor

[source, scala]

RemoveExecutor( execId: String)


When received, BlockManagerMasterEndpoint <execId is removed>> and the response true sent back.

Posted when BlockManagerMaster.md#removeExecutor[BlockManagerMaster removes an executor].

=== [[StopBlockManagerMaster]] StopBlockManagerMaster

[source, scala]

StopBlockManagerMaster

When received, BlockManagerMasterEndpoint...FIXME

Posted when...FIXME

=== [[UpdateBlockInfo]] UpdateBlockInfo

[source, scala]

UpdateBlockInfo( blockManagerId: BlockManagerId, blockId: BlockId, storageLevel: StorageLevel, memSize: Long, diskSize: Long)


When received, BlockManagerMasterEndpoint...FIXME

Posted when BlockManagerMaster is requested to storage:BlockManagerMaster.md#updateBlockInfo[handle a block status update (from BlockManager on an executor)].

== [[storageStatus]] storageStatus Internal Method

[source,scala]

storageStatus: Array[StorageStatus]

storageStatus...FIXME

storageStatus is used when BlockManagerMasterEndpoint is requested to handle <> message.

== [[getLocationsMultipleBlockIds]] getLocationsMultipleBlockIds Internal Method

[source,scala]

getLocationsMultipleBlockIds( blockIds: Array[BlockId]): IndexedSeq[Seq[BlockManagerId]]


getLocationsMultipleBlockIds...FIXME

getLocationsMultipleBlockIds is used when BlockManagerMasterEndpoint is requested to handle <> message.

== [[removeShuffle]] removeShuffle Internal Method

[source,scala]

removeShuffle( shuffleId: Int): Future[Seq[Boolean]]


removeShuffle...FIXME

removeShuffle is used when BlockManagerMasterEndpoint is requested to handle <> message.

== [[getPeers]] getPeers Internal Method

[source, scala]

getPeers( blockManagerId: BlockManagerId): Seq[BlockManagerId]


getPeers finds all the registered BlockManagers (using <> internal registry) and checks if the input blockManagerId is amongst them.

If the input blockManagerId is registered, getPeers returns all the registered BlockManagers but the one on the driver and blockManagerId.

Otherwise, getPeers returns no BlockManagers.

NOTE: Peers of a storage:BlockManager.md[BlockManager] are the other BlockManagers in a cluster (except the driver's BlockManager). Peers are used to know the available executors in a Spark application.

getPeers is used when BlockManagerMasterEndpoint is requested to handle <> message.

== [[register]] register Internal Method

[source, scala]

register( idWithoutTopologyInfo: BlockManagerId, maxOnHeapMemSize: Long, maxOffHeapMemSize: Long, slaveEndpoint: RpcEndpointRef): BlockManagerId


register registers a storage:BlockManager.md[] (based on the given storage:BlockManagerId.md[]) in the <> and <> registries and posts a SparkListenerBlockManagerAdded message (to the <>).

NOTE: The input maxMemSize is the storage:BlockManager.md#maxMemory[total available on-heap and off-heap memory for storage on a BlockManager].

NOTE: Registering a BlockManager can only happen once for an executor (identified by BlockManagerId.executorId in <> internal registry).

If another BlockManager has earlier been registered for the executor, you should see the following ERROR message in the logs:

[source,plaintext]

Got two different block manager registrations on same executor - will replace old one [oldId] with new one [id]

And then <>.

register prints out the following INFO message to the logs:

[source,plaintext]

Registering block manager [hostPort] with [bytes] RAM, [id]

The BlockManager is recorded in the internal registries:

  • <>
  • <>

In the end, register requests the <> to scheduler:LiveListenerBus.md#post[post] a ROOT:SparkListener.md#SparkListenerBlockManagerAdded[SparkListenerBlockManagerAdded] message.

register is used when BlockManagerMasterEndpoint is requested to handle <> message.

== [[removeExecutor]] removeExecutor Internal Method

[source, scala]

removeExecutor( execId: String): Unit


removeExecutor prints the following INFO message to the logs:

[source,plaintext]

Trying to remove executor [execId] from BlockManagerMaster.

If the execId executor is registered (in the internal <> internal registry), removeExecutor <BlockManager>>.

removeExecutor is used when BlockManagerMasterEndpoint is requested to handle <> or <> messages.

== [[removeBlockManager]] removeBlockManager Internal Method

[source, scala]

removeBlockManager( blockManagerId: BlockManagerId): Unit


removeBlockManager looks up blockManagerId and removes the executor it was working on from the internal registries:

  • <>
  • <>

It then goes over all the blocks for the BlockManager, and removes the executor for each block from blockLocations registry.

ROOT:SparkListener.md#SparkListenerBlockManagerRemoved[SparkListenerBlockManagerRemoved(System.currentTimeMillis(), blockManagerId)] is posted to ROOT:SparkContext.md#listenerBus[listenerBus].

You should then see the following INFO message in the logs:

[source,plaintext]

Removing block manager [blockManagerId]

removeBlockManager is used when BlockManagerMasterEndpoint is requested to <> (to handle <> or <> messages).

== [[getLocations]] getLocations Internal Method

[source, scala]

getLocations( blockId: BlockId): Seq[BlockManagerId]


getLocations looks up the given storage:BlockId.md[] in the blockLocations internal registry and returns the locations (as a collection of BlockManagerId) or an empty collection.

getLocations is used when BlockManagerMasterEndpoint is requested to handle <> and <> messages.

== [[logging]] Logging

Enable ALL logging level for org.apache.spark.storage.BlockManagerMasterEndpoint logger to see what happens inside.

Add the following line to conf/log4j.properties:

[source]

log4j.logger.org.apache.spark.storage.BlockManagerMasterEndpoint=ALL

Refer to ROOT:spark-logging.md[Logging].

== [[internal-properties]] Internal Properties

=== [[blockManagerIdByExecutor]] blockManagerIdByExecutor Lookup Table

[source,scala]

blockManagerIdByExecutor: Map[String, BlockManagerId]

Lookup table of storage:BlockManagerId.md[]s by executor ID

A new executor is added when BlockManagerMasterEndpoint is requested to handle a <> message (and <>).

An executor is removed when BlockManagerMasterEndpoint is requested to handle a <> and a <> messages (via <>)

Used when BlockManagerMasterEndpoint is requested to handle <> message, <>, <> and <>.

=== [[blockManagerInfo]] blockManagerInfo Lookup Table

[source,scala]

blockManagerIdByExecutor: Map[String, BlockManagerId]

Lookup table of storage:BlockManagerInfo.md[] by storage:BlockManagerId.md[]

A new BlockManagerInfo is added when BlockManagerMasterEndpoint is requested to handle a <> message (and <>).

A BlockManagerInfo is removed when BlockManagerMasterEndpoint is requested to <> (to handle <> and <> messages).

=== [[blockLocations]] blockLocations

[source,scala]

blockLocations: Map[BlockId, Set[BlockManagerId]]

Collection of storage:BlockId.md[] and their locations (as BlockManagerId).

Used in removeRdd to remove blocks for a RDD, removeBlockManager to remove blocks after a BlockManager gets removed, removeBlockFromWorkers, updateBlockInfo, and <>.


Last update: 2020-10-06