Troubleshooting methods for Zookeeper on CentOS

Troubleshooting Guide for ZooKeeper under CentOS System

This article provides a step-by-step guide to help you effectively troubleshoot ZooKeeper faults on CentOS systems.

1. Verify the status of the ZooKeeper service

First, check the status of the ZooKeeper service using the following command:

 sudo systemctl status zookeeper

If the service is not running, start with the following command:

 sudo systemctl start zookeeper

To make it power on and start:

 sudo systemctl enable zookeeper

2. Analyze ZooKeeper logs

Check the ZooKeeper log file (usually located in /var/log/zookeeper/zookeeper.out ) for troubleshooting clues.

3. Check the configuration file zoo.cfg

Carefully check the zoo.cfg file to ensure that all parameters (server address, data directory, client port, etc.) are configured correctly.

4. Check the firewall settings

Confirm that the firewall does not block the port used by ZooKeeper (default port 2181). You can temporarily close the firewall using the following command (production environment is not recommended):

 sudo systemctl stop firewalld.service

Alternatively, permanently shut down the firewall ( a more secure firewall policy is strongly recommended in production environments, such as allowing specific IP addresses to access port 2181 ):

 sudo systemctl stop firewalld
sudo systemctl disable firewalld

5. Verify Java environment

Make sure Java environment variables are set correctly. You can edit the /etc/profile file, add the following and execute source /etc/profile to make the configuration take effect:

 export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk # Please replace it with your Java installation path export CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export ZOOKEEPER_HOME=/etc/apache/zookeeper # Please replace it with your ZooKeeper installation path export PATH=$ZOOKEEPER_HOME/bin:$PATH

6. Use four-character command to monitor the cluster

ZooKeeper provides a set of four-word commands (such as stat , ruok , mntr ) for monitoring cluster status and debugging problems.

7. Test network connection between nodes

Use the ping or telnet command to test network connectivity between all nodes in the ZooKeeper cluster.

8. Monitor resource usage

Check the node's CPU, memory, and disk usage to identify potential resource bottlenecks.

9. Handle FAQs

• Node downtime: Check the abnormal situation before the node downtime, confirm whether the server resources are sufficient, and check the node disk I/O performance.
• Network problem: Check the network connection between servers to ensure that the ZooKeeper nodes can communicate with each other.
• Frequent Leader Switching: Check the performance and network status of the Leader node to see if there is any failure in Follower synchronization in the log.

If the problem persists, please refer to the official ZooKeeper documentation or seek community support. Remember to operate your firewall settings carefully in production environments and prioritize safer alternatives.

The above is the detailed content of Troubleshooting methods for Zookeeper on CentOS. For more information, please follow other related articles on the PHP Chinese website!