@InterfaceAudience.Public @InterfaceStability.Unstable public class ApplicationMaster extends Object
This class is meant to act as an example on how to write yarn-based application masters.
The ApplicationMaster is started on a container by the
ResourceManager's launcher. The first thing that the
ApplicationMaster needs to do is to connect and register itself
with the ResourceManager. The registration sets up information
within the ResourceManager regarding what host:port the
ApplicationMaster is listening on to provide any form of functionality to a
client as well as a tracking url that a client can use to keep track of
status/job history if needed. However, in the distributedshell, trackingurl
and appMasterHost:appMasterRpcPort are not supported.
The ApplicationMaster needs to send a heartbeat to the
ResourceManager at regular intervals to inform the
ResourceManager that it is up and alive. The
ApplicationMasterProtocol.allocate(org.apache.hadoop.yarn.api.protocolrecords.AllocateRequest) to the ResourceManager from the
ApplicationMaster acts as a heartbeat.
For the actual handling of the job, the ApplicationMaster has to
request the ResourceManager via AllocateRequest for the
required no. of containers using ResourceRequest with the necessary
resource specifications such as node location, computational
(memory/disk/cpu) resource requirements. The ResourceManager
responds with an AllocateResponse that informs the
ApplicationMaster of the set of newly allocated containers,
completed containers as well as current state of available resources.
For each allocated container, the ApplicationMaster can then set
up the necessary launch context via ContainerLaunchContext to specify
the allocated container id, local resources required by the executable, the
environment to be setup for the executable, commands to execute, etc. and
submit a StartContainerRequest to the ContainerManagementProtocol to
launch and execute the defined commands on the given allocated container.
The ApplicationMaster can monitor the launched container by
either querying the ResourceManager using
ApplicationMasterProtocol.allocate(org.apache.hadoop.yarn.api.protocolrecords.AllocateRequest) to get updates on completed containers or via
the ContainerManagementProtocol by querying for the status of the allocated
container's ContainerId.
After the job has been completed, the ApplicationMaster has to
send a FinishApplicationMasterRequest to the
ResourceManager to inform it that the
ApplicationMaster has been completed.
| 修飾子とタイプ | フィールドと説明 |
|---|---|
protected ApplicationAttemptId |
appAttemptID |
protected Set<ContainerId> |
launchedContainers |
protected AtomicInteger |
numAllocatedContainers |
protected AtomicInteger |
numRequestedContainers |
protected int |
numTotalContainers |
| コンストラクタと説明 |
|---|
ApplicationMaster() |
| 修飾子とタイプ | メソッドと説明 |
|---|---|
protected boolean |
finish() |
boolean |
init(String[] args)
Parse command line options
|
static void |
main(String[] args) |
void |
run()
Main run function for the application master
|
protected ApplicationAttemptId appAttemptID
protected int numTotalContainers
protected AtomicInteger numAllocatedContainers
protected AtomicInteger numRequestedContainers
protected final Set<ContainerId> launchedContainers
public ApplicationMaster()
public boolean init(String[] args) throws org.apache.commons.cli.ParseException, IOException
args - Command line argsorg.apache.commons.cli.ParseExceptionIOExceptionpublic void run() throws YarnException, IOException, InterruptedException
protected boolean finish()
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