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[SOLVED] How can you stop an unstoppable zombie job on Jenkins without restarting the server? - jenkins

[SOLVED] How to Terminate an Unstoppable Zombie Job in Jenkins Without Restarting the Server

In this chapter, we will look at simple ways to handle an unstoppable zombie job in Jenkins. Zombie jobs can stay stuck for a long time. They take up system resources and mess up our CI/CD pipeline. We will show you different ways to find and stop these stubborn jobs without restarting our Jenkins server. By using these methods, we can take back control of our Jenkins environment. This will help us have smoother operations in the future.

Solutions Discussed in This Chapter:

  • Part 1 - Identify the Zombie Job Using the Jenkins UI
  • Part 2 - Kill the Zombie Job via the Jenkins Script Console
  • Part 3 - Use the Jenkins CLI to Terminate the Job
  • Part 4 - Force Stop the Job by Modifying the Build Process
  • Part 5 - Investigate and Resolve Underlying Issues
  • Part 6 - Prevent Future Zombie Jobs from Occurring

If we want to learn more about Jenkins, we can check our guides on how to trigger Jenkins builds and how to call Jenkins builds. By using these tips, we can manage our Jenkins jobs better. This will help us keep a healthy CI/CD pipeline.

Part 1 - Identify the Zombie Job Using the Jenkins UI

To find a zombie job in Jenkins, we can go to the Jenkins dashboard and do these steps:

  1. Access the Dashboard: First, open your Jenkins and log in.
  2. Check the Build History: Look at the build history for your jobs on the main dashboard. Zombie jobs usually show as builds that are stuck or running forever.
  3. View Job Details: Click on the job name to see more details. Check the build status. If it says “in progress” for too long, it might be a zombie job.
  4. Monitor Executors: Go to Manage Jenkins > Manage Nodes and Clouds. Here, we can see the status of each executor. If one executor is busy with a job that does not respond, it could mean a zombie job is there.
  5. Inspect Logs: Click on the specific build number. Then go to the “Log” section to find any errors or messages that show the job is not moving forward.

Identifying the zombie job using the Jenkins UI is important to fix the problem. For more help, we can use the Jenkins Script Console or Jenkins CLI to have more control over jobs that are stuck.

Part 2 - Kill the Zombie Job via the Jenkins Script Console

To stop a zombie job in Jenkins using the Script Console, we can follow some simple steps.

  1. Access the Script Console:

    • Go to http://<your-jenkins-url>/script.

  2. Identify the Job:

    • Find the job name and build number that we want to stop. We can see this information in the Jenkins UI.

  3. Execute the Script:

    • We can use this Groovy script to kill the job:
    def jobName = '<your-job-name>'
def buildNumber = <your-build-number>

def job = Jenkins.instance.getItem(jobName)
def build = job.getBuildByNumber(buildNumber)

if (build) {
    build.doStop()
    println "Successfully stopped the job: ${jobName}, Build Number: ${buildNumber}"
} else {
    println "Build not found."
}

  4. Run the Script:

    • Just paste the script into the Script Console and click on “Run”. This will stop the job we picked without needing to restart the server.

This way is good to stop stuck or zombie jobs in Jenkins. For more help with Jenkins, we can check out how to trigger Jenkins builds or look at Jenkins CLI options to manage jobs.

Part 3 - Use the Jenkins CLI to Terminate the Job

We can stop a zombie job on Jenkins with the Jenkins CLI. Here are the steps to do it:

  1. Access the Jenkins CLI: First, we need the Jenkins CLI jar file. We can download it from our Jenkins server at http://<your-jenkins-url>/jnlpJars/jenkins-cli.jar.

  2. Connect to Your Jenkins Server: Next, we use this command to connect to our Jenkins server. We replace <username> and <api-token> with our Jenkins details.

    java -jar jenkins-cli.jar -s http://<your-jenkins-url> -auth <username>:<api-token> list-jobs

  3. Identify the Job: We run this command to list all jobs. This helps us find the job we want to stop.

    java -jar jenkins-cli.jar -s http://<your-jenkins-url> -auth <username>:<api-token> list-jobs

  4. Terminate the Job: After we find the job name and the build number, we use this command to stop the job:

    java -jar jenkins-cli.jar -s http://<your-jenkins-url> -auth <username>:<api-token> stop-build <job-name> <build-number>

    For example:

    java -jar jenkins-cli.jar -s http://localhost:8080 -auth admin:myapitoken stop-build my-job 12

  5. Verify Job Status: After we stop the job, we can check the job status. We can look at the build logs or run this command:

    java -jar jenkins-cli.jar -s http://<your-jenkins-url> -auth <username>:<api-token> get-job <job-name>

For more details on commands and how to use them, we can look at the Jenkins CLI documentation. If we have problems, we can check this link how to authenticate Jenkins CI to handle our credentials correctly.

Part 4 - Force Stop the Job by Modifying the Build Process

To force stop a zombie job on Jenkins by changing the build process, we can use several methods. It depends on what kind of job we have. Here are the steps:

  1. Access Job Configuration:

    • We go to the Jenkins dashboard. Then we select the job that has a problem. After that, we click on “Configure”.

  2. Modify Build Steps:

    • We can change the build step to add a fail command. For example, if we use a shell command, we can add:

      exit 1

    • This command makes the job fail right away. This helps us regain control.

  3. Use Timeout Plugin:

    • If we have the Timeout plugin, we can set a timeout for the job. In the “Build Environment” section, we enable “Abort the build if it’s stuck”.
    • We need to set a good timeout duration in the configuration.

  4. Abort via Job DSL:

    • If we are using Job DSL, we can add an abort condition in our job scripts:

      if (/* condition to check if job is zombie */) {
    currentBuild.result = 'ABORTED'
}

  5. Environment Variable Override:

    • If long-running processes freeze, we can change environment variables to force a stop. For example, we can set a variable that the script checks. If it is true, the script exits:

      export FORCE_STOP=true

  6. Immediate Kill Command:

    • If we can access the Jenkins server directly, we find the process ID (PID) of the job. We can use this command to find the PID:

      ps aux | grep jenkins

    • Then we can kill the specific process with:

      kill -9 <PID>

We should monitor our Jenkins jobs after doing these steps. It helps to check if they work as we expect. Also, we should look for underlying issues that can make jobs unresponsive.

Part 5 - Investigate and Resolve Underlying Issues

To stop a zombie job on Jenkins, we need to look into the problems that make jobs hang or not respond. Here are some steps to help us find and fix these issues:

  1. Check the Job Configuration:

    • We should review the job’s settings. Look for any mistakes that could cause the job to wait forever or hang. Make sure all paths, parameters, and scripts are correct.

  2. Review Console Output:

    • We can check the console output of the zombie job. This helps us find any errors or logs that show where the job got stuck. Look for errors or warnings that happen a lot. They can give us clues about the issue.

  3. Identify System Resource Utilization:

    • We need to monitor system resources like CPU, memory, and disk I/O while the job runs. This helps us see if the server is too busy. We can use tools like top, htop, or vmstat on our Jenkins server to check resource usage.

  4. Examine External Dependencies:

    • We should find out if the job uses any external services or resources, like databases or APIs, that may be slow or not working. We need to look into any connection problems or timeouts that could make the job hang.

  5. Check for Deadlocks:

    • If our job runs many things at once, we must check for deadlocks. We can look at log files or use tools to find any deadlocks happening during the job.

  6. Review Plugins:

    • Some Jenkins plugins may cause problems. We should check if any plugins are old or not compatible. These can interfere with how the job runs. We need to update or turn off any plugins that cause issues.

  7. Log Analysis:

    • We should check Jenkins logs in the $JENKINS_HOME/logs folder for any errors or warnings about the job or Jenkins itself. This can help us find problems with Jenkins.

  8. Run Jobs in Isolation:

    • If we can, we should run the job on a different Jenkins instance or in a controlled space. This can help us see if the problem is with the job itself or with the Jenkins setup.

  9. Consult Community and Documentation:

    • We can look at Jenkins community forums or documentation. Others may have faced similar problems. There might already be solutions or workarounds.

By carefully checking these areas, we can find out why the zombie job happens in Jenkins. Then we can take steps to fix the problems. For more details on managing Jenkins jobs, we can check how to trigger Jenkins build.

Part 6 - Prevent Future Zombie Jobs from Occurring

To stop zombie jobs from happening in Jenkins, we can use some simple practices and settings.

  1. Set Build Timeouts: We should set time limits for each job. This helps to stop any job that takes too long. It will not turn into a zombie job.

    • Go to job settings and add the Build Timeout option.
    • Pick a good timeout, like 10 minutes.

  2. Use the Lockable Resources Plugin: This plugin helps us manage builds at the same time. By locking resources, we can stop problems that make zombie jobs.

    • Install the Lockable Resources plugin from the Jenkins plugin manager.
    • Set up resources in Jenkins UI and link them to jobs.

  3. Regular Maintenance: We should check and clean up old builds and jobs now and then. We can automate this with the Discard Old Builds feature in job settings.

    • Set jobs to delete builds older than a certain number of days or keep just a few builds.

  4. Monitor Job Execution: We can use Jenkins monitoring tools or plugins like the Monitoring Plugin to watch job times and resource use. This helps us find jobs that often fail or get stuck.

  5. Handle Dependencies Properly: We need to make sure our jobs do not rely on other jobs that fail or get stuck. Using the Jenkins Pipeline feature helps us manage dependencies and flow of builds better.

  6. Check for Resource Exhaustion: We must ensure our Jenkins server has enough resources like CPU and memory for the jobs. We should keep an eye on the server’s resource use and upgrade if needed.

  7. Use Post-Build Actions: We can set up actions after a job finishes. This helps clean up resources. We should delete temporary files or stop processes that might cause future jobs to hang.

By doing these things, we can greatly lower the chances of zombie jobs in Jenkins. For more tips on managing Jenkins jobs well, we can read about how to trigger Jenkins builds and handle build failures.

Frequently Asked Questions

1. What is a zombie job in Jenkins?

A zombie job in Jenkins is a build or job that gets stuck and cannot be stopped easily. These jobs can lock resources and slow down the Jenkins server. If we want to learn how to stop a zombie job without restarting the server, we can check our guide.

2. How can I identify a zombie job in Jenkins?

We can find a zombie job in Jenkins by looking at the Jenkins UI. We should look for jobs that say ‘Building’ for too long without doing anything. For more steps on finding these jobs, we can see our part on identifying zombie jobs in Jenkins.

3. What is the Jenkins Script Console, and how is it used to stop jobs?

The Jenkins Script Console is a tool for admins to run Groovy scripts on the Jenkins server. We can use it to stop a zombie job by writing a script to end the running process. For more information, we can read our guide on killing zombie jobs using the Jenkins Script Console.

4. Can I terminate a Jenkins job using the CLI?

Yes, we can stop a Jenkins job using the Jenkins CLI (Command Line Interface). The CLI gives us commands to manage Jenkins jobs. This includes stopping jobs that do not respond. For instructions on how to use the Jenkins CLI to stop jobs, we can check our section on this method.

5. How can I prevent zombie jobs from occurring in Jenkins?

To stop zombie jobs in Jenkins, we should regularly check job settings and how resources are used. Setting timeouts and looking at build scripts can help reduce unresponsive jobs. For a detailed way to prevent zombie jobs, we can see our section on fixing issues in Jenkins.

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