Monitoring YARN NodeManager Status
Monitoring the status of YARN NodeManagers is crucial for maintaining the health and performance of your Hadoop cluster. There are several ways to check the status of YARN NodeManagers, which are outlined below.
Using the YARN Web UI
The YARN Web UI provides a graphical interface to monitor the status of YARN NodeManagers. To access the YARN Web UI, follow these steps:
- Open a web browser and navigate to the YARN ResourceManager web UI, typically available at
http://<resourcemanager-host>:8088
.
- In the YARN Web UI, click on the "Nodes" tab to view the list of YARN NodeManagers and their status.
The YARN Web UI displays information such as the NodeManager's host, state, health, available resources, and running containers.
Using the YARN CLI
You can also check the status of YARN NodeManagers using the YARN command-line interface (CLI). The following command displays the list of YARN NodeManagers and their status:
yarn node -list
This command will output a table with the following information for each NodeManager:
Column |
Description |
Node ID |
The unique identifier of the NodeManager |
Node State |
The current state of the NodeManager (e.g., RUNNING, UNHEALTHY) |
Node HTTP Address |
The HTTP address of the NodeManager |
Number of Running Containers |
The number of containers currently running on the NodeManager |
Node Manager Version |
The version of the YARN NodeManager |
Monitoring NodeManager Logs
The YARN NodeManager logs can provide valuable information about the status and health of the NodeManager. The logs are typically located in the $HADOOP_LOG_DIR
directory on the node. You can use the following command to view the NodeManager logs:
tail -n 100 $HADOOP_LOG_DIR/yarn- < user > -nodemanager- < hostname > .log
This command will display the last 100 lines of the NodeManager log file, which can help you identify any issues or errors related to the NodeManager.
By using the YARN Web UI, CLI, and log files, you can effectively monitor the status of YARN NodeManagers in your Hadoop cluster.