🚨 Troubleshooting YARN in 2025: Common Issues & Fixes

Apache YARN (Yet Another Resource Negotiator) remains a critical component for managing resources in Hadoop clusters. As systems scale, new challenges emerge. In this guide, we’ll explore the most common YARN issues in 2025 and practical solutions to keep your cluster running smoothly.

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1️⃣ ResourceManager Not Starting
Issue: The YARN ResourceManager fails to start due to configuration errors or state corruption.
Fix:

• Check ResourceManager logs for errors:
  cat /var/log/hadoop-yarn/yarn-yarn-resourcemanager.log | grep ERROR
• Verify the hostname in yarn-site.xml:
  grep yarn.resourcemanager.hostname /etc/hadoop/conf/yarn-site.xml
• Clear state corruption and restart:
  rm -rf /var/lib/hadoop-yarn/yarn-*.state
systemctl restart hadoop-yarn-resourcemanager

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2️⃣ NodeManager Crashing or Not Registering
Issue: NodeManager does not appear in the ResourceManager UI or crashes frequently.
Fix:

• Check NodeManager logs:
  cat /var/log/hadoop-yarn/yarn-yarn-nodemanager.log | grep ERROR
• Ensure sufficient memory and CPU allocation:
  grep -E 'yarn.nodemanager.resource.memory-mb|yarn.nodemanager.resource.cpu-vcores' /etc/hadoop/conf/yarn-site.xml
• Restart NodeManager:
  systemctl restart hadoop-yarn-nodemanager

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3️⃣ Applications Stuck in ACCEPTED State
Issue: Jobs remain in the "ACCEPTED" state indefinitely without progressing.
Fix:

• Check cluster resource availability:
  yarn node -list
• Verify queue capacities:
  yarn queue -status <queue_name>
• Restart ResourceManager if required:
  systemctl restart hadoop-yarn-resourcemanager

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4️⃣ High Container Allocation Delays
Issue: Jobs take longer to start due to slow container allocation.
Fix:

• Check pending resource requests:
  yarn application -list -appStates RUNNING
• Verify scheduler settings:
  grep -E 'yarn.scheduler.maximum-allocation-mb|yarn.scheduler.maximum-allocation-vcores' /etc/hadoop/conf/yarn-site.xml
• Ensure NodeManagers have available resources:
  yarn node -list | grep RUNNING

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5️⃣ ApplicationMaster Failures
Issue: Jobs fail due to ApplicationMaster crashes.
Fix:

• Check ApplicationMaster logs for errors:
  yarn logs -applicationId <application_id>
• Increase retry limits if necessary:
  grep yarn.resourcemanager.am.max-attempts /etc/hadoop/conf/yarn-site.xml
• Restart the job if needed:
  yarn application -kill <application_id>

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By following these troubleshooting steps, you can quickly diagnose and resolve common YARN issues in 2025, ensuring smooth cluster operations .For more details refer cloudera CDP documentations https://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/YARN.html