Suspend-Job

Suspend-Job: Temporarily Stop Workflow Jobs

Welcome back to Wahmans PowerShell Blog! Today we are diving into the Suspend-Job cmdlet, a useful command for managing background jobs in PowerShell workflows. According to the official Microsoft documentation, Suspend-Job is used to temporarily stop workflow jobs. Unlike Stop-Job, which terminates a job, Suspend-Job allows you to pause a running workflow job and resume it later using Resume-Job.

When and Why Would You Use Suspend-Job?

You might want to suspend a job to conserve system resources, troubleshoot certain workflow steps, or to delay execution until certain other tasks are complete. This is particularly useful in long-running workflows where conditional scheduling or manual intervention is needed.

Let’s dive into some practical examples from beginner to advanced usage:

Example 1: Suspending a Basic Workflow Job

Let’s create a basic workflow and suspend it after it starts.

workflow Test-Workflow {
    Write-Output "Starting Workflow"
    Start-Sleep -Seconds 30
    Write-Output "Ending Workflow"
}

# Start the workflow job
$job = Test-Workflow -AsJob

# Suspend the job after a few seconds
Start-Sleep -Seconds 5
Suspend-Job -Id $job.Id

This will pause the job mid-way through the Start-Sleep call.

Example 2: Suspending a Job by Name

If you know the name of the job, you can also suspend it using the Name parameter:

Suspend-Job -Name 'Test-Workflow'

This approach can be more readable and easier to manage in scripts where job names are predefined.

Example 3: Automatically Suspend Long-Running Workflows

Want to automatically pause workflows that run past a certain time? Use logic to check job run time and suspend if needed.

$jobs = Get-Job | Where-Object { $_.Command -eq 'Test-Workflow' -and $_.State -eq 'Running' }
foreach ($job in $jobs) {
    if ($job.PSBeginTime -and ((Get-Date) - $job.PSBeginTime).TotalSeconds -gt 10) {
        Suspend-Job -Id $job.Id
        Write-Output "Suspended job with ID $($job.Id) due to long runtime"
    }
}

This ensures your workflows don’t consume unlimited resources.

Example 4: Advanced — Suspend Workflow Based on External Condition

Let’s say we only want to allow a workflow to proceed if a certain service is running. If the service isn’t running, suspend the job:

workflow Monitor-Service {
    Write-Output "Checking Service Status"
    Start-Sleep -Seconds 5
    Write-Output "Service Status Checked"
}

$job = Monitor-Service -AsJob
Start-Sleep -Seconds 2

$service = Get-Service -Name 'Spooler'
if ($service.Status -ne 'Running') {
    Suspend-Job -Id $job.Id
    Write-Output "Suspended job because Print Spooler service is not running."
}

This adds another level of dynamic control over your job execution.

Conclusion

Suspend-Job can be a valuable tool when working with long-running or conditional workflows in PowerShell. It allows for greater control, flexibility, and responsiveness in your scripts and job management. Remember, this cmdlet works with workflow jobs only, so plan accordingly when designing your automation processes.

Happy scripting, and I will see you in the next post!