There are several ways that you can tune the
performance of Apache Yarn, the resource management platform in Hadoop:
- Increase the number of resources available: By
increasing the amount of memory and CPU available to Yarn, you can improve
the performance of your applications. You can do this by increasing the
values of the yarn.nodemanager.resource.memory-mb and
yarn.nodemanager.resource.cpu-vcores
configuration parameters.
- Increase the number of NodeManagers: Adding
more NodeManagers to your cluster can improve the performance of Yarn by
allowing it to schedule tasks across more resources. You can do this by
installing additional NodeManagers on new machines and adding them to the
cluster.
- Enable preemption: By enabling preemption,
Yarn will be able to reclaim resources from applications that are using
them inefficiently and allocate them to other applications that need them.
You can enable preemption by setting the yarn.resourcemanager.scheduler.monitor.enable
configuration parameter to true.
- Use Yarn's resource types feature: Yarn's
resource types feature allows you to specify different types of resources,
such as GPUs or FPGAs, and allocate them to applications that need them.
This can improve the performance of resource-intensive applications by
ensuring that they have access to the resources they need.
- Enable short-circuit reads: Short-circuit
reads allow MapReduce tasks to read data directly from local disks, rather
than transferring it over the network. This can improve the performance of
MapReduce jobs that read large amounts of data by
Increase
the number of resources available with example
To increase the number of resources available to
Yarn, you can adjust the yarn.nodemanager.resource.memory-mb and yarn.nodemanager.resource.cpu-vcores
configuration parameters.
For example, to increase the amount of memory
available to Yarn to 8 GB and the number of CPU cores to 4, you can set the
following configuration parameters in the yarn-site.xml file:
<property>
<name>yarn.nodemanager.resource.memory-mb</name>
<value>8192</value>
</property>
<property>
<name>yarn.nodemanager.resource.cpu-vcores</name>
<value>4</value>
</property>
These values will apply to all NodeManagers in the
cluster. You will need to restart the NodeManagers for the changes to take
effect.
It's important to note that increasing the
resources available to Yarn can improve the performance of your applications, but
it can also increase the resource requirements of your cluster. You will need
to carefully evaluate the specific requirements and constraints of your
environment to determine the optimal values for these parameters.
Increase
the number of NodeManagers with example
To increase the number of NodeManagers in your Yarn
cluster, you will need to install additional NodeManagers on new machines and
add them to the cluster.
Here is an example of how you might do this:
- Install Hadoop on the new machines and
configure the hadoop-env.sh and yarn-env.sh
files to specify the necessary environment variables, such as the Java
home directory and the location of the Hadoop configuration files.
- Start the NodeManager daemon on the new
machines by running the yarn-daemon.sh script:
$ yarn-daemon.sh start
nodemanager
- Add the new NodeManagers to the yarn-site.xml
file on the ResourceManager machine, specifying the hostnames and ports of
the new NodeManagers:
<property>
<name>yarn.resourcemanager.nodes.include-path</name>
<value>/etc/hadoop/conf/nodes</value>
</property>
# In the nodes file:
node1
node2
node3
- Restart the ResourceManager and the
NodeManagers for the changes to take effect:
$ yarn-daemon.sh restart
resourcemanager
$ yarn-daemon.sh restart
nodemanager
This is just one example of how you can increase
the number of NodeManagers in a Yarn cluster. There are many other factors to
consider, such as network configuration, security, and resource allocation. You
will need to carefully evaluate the specific requirements and constraints of
your environment to determine the best approach.
Enable
preemption with example
To enable preemption in Yarn, you will need to set
the yarn.resourcemanager.scheduler.monitor.enable
configuration parameter to true.
Here is an example of how you might do this in the yarn-site.xml file:
<property>
<name>yarn.resourcemanager.scheduler.monitor.enable</name>
<value>true</value>
</property>
Once you have set this configuration parameter, you
will need to restart the ResourceManager and NodeManagers for the changes to
take effect:
$ yarn-daemon.sh restart
resourcemanager
$ yarn-daemon.sh restart
nodemanager
It's important to note that enabling preemption can
improve the performance of Yarn by allowing it to reclaim resources from
applications that are using them inefficiently and allocate them to other
applications that need them. However, it can also lead to increased resource
contention, since applications may be preempted to make way for other
applications. You will need to carefully evaluate the specific requirements and
constraints of your environment to determine whether enabling preemption is a
suitable solution.
Use
Yarn's resource types feature
Yarn's resource types feature allows you to specify
different types of resources, such as GPUs or FPGAs, and allocate them to
applications that need them. This can improve the performance of
resource-intensive applications by ensuring that they have access to the
resources they need.
To use Yarn's resource types feature, you will need
to do the following:
- Define the resource types in the yarn-site.xml
file on the ResourceManager machine. For example:
<property>
<name>yarn.resource-types</name>
<value>gpu,fpga</value>
</property>
- Configure the NodeManagers to expose the
resource types that they have available. For example:
<property>
<name>yarn.nodemanager.resource.gpu.enabled</name>
<value>true</value>
</property>
<property>
<name>yarn.nodemanager.resource.gpu.path</name>
<value>/usr/local/nvidia</value>
</property>
<property>
<name>yarn.nodemanager.resource.fpga.enabled</name>
<value>true</value>
</property>
<property>
<name>yarn.nodemanager.resource.fpga.path</name>
<value>/usr/local/altera</value>
</property>
- Update the application submission script to
request the specific resource types that the application requires. For
example:
# In the application submission
script:
--resources gpu=2,fpga=1
This will request 2 GPUs and 1 FPGA for the
application.
It's important to note that Yarn's resource types
feature is a powerful tool for improving the performance of resource-intensive
applications, but it can also add an additional layer of complexity to your
cluster. You will need to carefully evaluate the specific requirements and
constraints of your environment to determine whether it is a suitable solution.
Enable
short-circuit reads
Short-circuit reads allow MapReduce tasks to read
data directly from local disks, rather than transferring it over the network.
This can improve the performance of MapReduce jobs that read large amounts of
data by reducing the amount of data transfer required.
To enable short-circuit reads in Yarn, you will
need to do the following:
- Set the dfs.client.read.shortcircuit
configuration parameter to true in the hdfs-site.xml file
on the client machines. This will enable short-circuit reads for HDFS:
<property>
<name>dfs.client.read.shortcircuit</name>
<value>true</value>
</property>
- Set the yarn.nodemanager.disk-health-checker.enable
configuration parameter to false in the yarn-site.xml
file on the NodeManager machines. This will disable the disk health
checker, which is necessary for short-circuit reads to work:
<property>
<name>yarn.nodemanager.disk-health-checker.enable</name>
<value>false</value>
</property>
- Restart the NodeManagers for the changes to
take effect:
$ yarn-daemon.sh restart
nodemanager
It's important to note that enabling short-circuit
reads can improve the performance of MapReduce jobs that read large amounts of
data, but it can also increase the load on the local disks and may not be
suitable for all environments. You will need to carefully evaluate the specific
requirements and constraints of your environment to determine whether it is a
suitable solution.
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