[JENKINS-39968] git checkouts are not pipeline-parallel safe

We have a specific workflow that enables us to discover that bug. However, it could and will probably happen to other people soon.

When running scm checkouts in parallels in a Jenkins file, the changes discovered are discovered for every git checkout that runs at the same time.

In our example, we run checkouts with 8 threads in parallel (background: https://roidelapluie.be/blog/2016/11/18/gitslave-jenkins/ ).

One change is displayed in 8 different repositories, the 8 repositories that are checked out at the same time.

The next checkouts do not contains the changes, so I guess it is kind of a global variable that is reset after the checkout.

lock('checkout') {

    def checkouts = [:]

    def threads = 8


    stage('Super Repo') {

checkout([$class: 'GitSCM',

branches: [[name: branch]],

doGenerateSubmoduleConfigurations: false,

extensions: [[$class: 'CleanCheckout'], [$class: 'ScmName', name: 'super']],

submoduleCfg: [],

userRemoteConfigs: [[url: "${gitBaseUrl}/${superRepo}"]]])

def repos = readFile('.gitslave')

def reposLines = repos.readLines()

for (i = 0; i < threads; i++){

    checkouts["Thread ${i}"] = []

}

def idx = 0

for (line in reposLines) {

    def repoInfo = line.split(' ')

    def repoUrl = repoInfo[0]

    def repoPath = repoInfo[1]

    def curatedRepoUrl = repoUrl.substring(4, repoUrl.length()-1)

    def curatedRepoPath = repoPath.substring(1, repoPath.length()-1)

    echo("Thread ${idx%threads}")

    checkouts["Thread ${idx%threads}"] << [path: curatedRepoPath, url: "${gitBaseUrl}/${curatedRepoUrl}"]

    idx++

}

    }

    stage('GitSlave Repos') {

def doCheckouts = [:]

for (i = 0; i < threads; i++){

    def j = i

    doCheckouts["Thread ${j}"] = {

for (co in checkouts["Thread ${j}"]) {

    retry(3) {

checkout([$class: 'GitSCM',

branches: [[name: branch]],

doGenerateSubmoduleConfigurations: false,

extensions: [[$class: 'RelativeTargetDirectory', relativeTargetDir: co.path], [$class: 'CleanCheckout'], [$class: 'ScmName', name: co.path]],

submoduleCfg: [],

userRemoteConfigs: [[url: co.url]]])

    }

}

    }

}

parallel doCheckouts

    }

---
Originally reported by roidelapluie, imported from: git checkouts are not pipeline-parallel safe

• status: Open
  
• priority: Major
  
• component(s): git-plugin, workflow-scm-step-plugin
  
• resolution: Unresolved
  
• votes: 5
  
• watchers: 10
  
• imported: 2025-12-02
  

Raw content of original issue

We have a specific workflow that enables us to discover that bug. However, it could and will probably happen to other people soon.


When running scm checkouts in parallels in a Jenkins file, the changes discovered are discovered for every git checkout that runs at the same time.


In our example, we run checkouts with 8 threads in parallel (background: https://roidelapluie.be/blog/2016/11/18/gitslave-jenkins/ ).


One change is displayed in 8 different repositories, the 8 repositories that are checked out at the same time.


The next checkouts do not contains the changes, so I guess it is kind of a global variable that is reset after the checkout.




lock('checkout') {

    def checkouts = [:]

    def threads = 8


    stage('Super Repo') {

        checkout([$class: 'GitSCM',

                branches: [[name: branch]],

                doGenerateSubmoduleConfigurations: false,

                extensions: [[$class: 'CleanCheckout'], [$class: 'ScmName', name: 'super']],

                submoduleCfg: [],

                userRemoteConfigs: [[url: "${gitBaseUrl}/${superRepo}"]]])

        def repos = readFile('.gitslave')

        def reposLines = repos.readLines()

        for (i = 0; i < threads; i++){

            checkouts["Thread ${i}"] = []

        }

        def idx = 0

        for (line in reposLines) {

            def repoInfo = line.split(' ')

            def repoUrl = repoInfo[0]

            def repoPath = repoInfo[1]

            def curatedRepoUrl = repoUrl.substring(4, repoUrl.length()-1)

            def curatedRepoPath = repoPath.substring(1, repoPath.length()-1)

            echo("Thread ${idx%threads}")

            checkouts["Thread ${idx%threads}"] << [path: curatedRepoPath, url: "${gitBaseUrl}/${curatedRepoUrl}"]

            idx++

        }

    }

    stage('GitSlave Repos') {

        def doCheckouts = [:]

        for (i = 0; i < threads; i++){

            def j = i

            doCheckouts["Thread ${j}"] = {

                for (co in checkouts["Thread ${j}"]) {

                    retry(3) {

                        checkout([$class: 'GitSCM',

                                branches: [[name: branch]],

                                doGenerateSubmoduleConfigurations: false,

                                extensions: [[$class: 'RelativeTargetDirectory', relativeTargetDir: co.path], [$class: 'CleanCheckout'], [$class: 'ScmName', name: co.path]],

                                submoduleCfg: [],

                                userRemoteConfigs: [[url: co.url]]])

                    }

                }

            }

        }

        parallel doCheckouts

    }

2 attachments

- [parallelcheckout.png](https://issues.jenkins.io/secure/attachment/34959/parallelcheckout.png)
> 
- [parallelcheckout2.png](https://issues.jenkins.io/secure/attachment/34958/parallelcheckout2.png)
>