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Dkron v4.0.9 Release - Enhanced Scheduling and Control

· 4 min read
The Dkron Team

We're pleased to announce the upcoming release of Dkron v4.0.9! This release brings several powerful new features and important fixes that enhance job scheduling control, resource management, and system reliability.

What's New in Dkron v4.0.9?​

Schedule Jobs with Precise Start Times​

One of the most requested features is now here! The new starts_at field allows you to schedule jobs to begin execution at a specific date and time. This is perfect for one-time events, maintenance windows, or any scenario where you need precise control over when a job becomes active.

{
  "name": "maintenance-job",
  "schedule": "@daily",
  "starts_at": "2025-12-20T02:00:00Z",
  "executor": "shell",
  "executor_config": {
    "command": "maintenance.sh"
  }
}

The UI has been updated to support this new field, making it easy to configure start times directly from the dashboard.

Pause and Resume Job Submissions​

Gain better control during maintenance windows or system updates with the new API endpoints to pause and unpause job submissions. When paused, no new jobs will be accepted, but existing scheduled jobs continue to run normally.

# Pause new job submissions
curl -X POST http://dkron-server:8080/v1/pause

# Resume job submissions
curl -X POST http://dkron-server:8080/v1/unpause

Memory Limits for Shell Executor Jobs​

Prevent runaway processes from consuming all system resources! You can now set memory limits for shell executor jobs using the new memory_limit configuration option. This helps ensure system stability and predictable resource usage.

{
  "executor": "shell",
  "executor_config": {
    "command": "data-processing.sh",
    "memory_limit": "512m"
  }
}

Enhanced Metrics and Monitoring​

Job execution metrics are now tracked using the go-metrics package, providing better insights into your job performance. Monitor execution times, success rates, and system health with greater precision.

Improved Concurrency Handling​

The "forbid" concurrency policy now correctly survives node restarts. Previously, jobs with concurrency set to "forbid" could incorrectly block after a node restart. This fix ensures your concurrency policies work reliably across the entire cluster lifecycle.

Bug Fixes and Improvements​

Critical Fixes​

  • Fixed nil pointer panic during startup: Resolved issues with Raft-dependent methods being called before initialization was complete
  • Fixed Docker startup with custom address pools: Dkron now works properly with custom Docker network configurations
  • Fixed mutex copy in processor plugin interface: Improved thread safety in plugin communications
  • Fixed dependent_jobs preservation: Job updates now correctly preserve existing dependent_jobs values

Developer Experience​

  • Mailpit integration: Replaced the unmaintained MailHog with actively maintained Mailpit for email testing
  • Documentation search: The documentation site now includes full-text search functionality
  • Architecture diagrams: Added comprehensive diagrams documenting the job execution flow
  • UI improvements: Job IDs are now visible on small screens for better mobile experience

Upgrading to v4.0.9​

Dkron v4.0.9 is designed to be a straightforward upgrade from v4.0.8. As always, we recommend:

  1. Backing up your data store before upgrading
  2. Testing the upgrade in a non-production environment first
  3. Following a rolling upgrade pattern for production clusters

What's Next?​

We continue to invest in making Dkron the most reliable and feature-rich distributed job scheduler. Future releases will focus on:

  • Enhanced observability with OpenTelemetry integration improvements
  • Advanced job dependencies and workflows
  • Performance optimizations for large-scale deployments

Get Dkron v4.0.9​

Community and Support​

Join our growing community:

Thank you to all our contributors who made this release possible, especially @NAlexandrov for the starts_at feature and @indeedhat for the dependent_jobs fix!

Happy scheduling!

The Dkron Team