jupyterlab_kernel_terminal_workspace_culler_extension

Automatically cull idle kernels, terminals, and workspaces after configurable timeout periods. Helps manage system resources by cleaning up unused resources that accumulate during long JupyterLab usage.

Features

• Idle kernel culling - Shut down kernels idle beyond timeout (checks execution_state and last_activity)
• Idle terminal culling - Close terminals with no WebSocket activity beyond timeout
• Workspace culling - Remove stale JupyterLab workspaces (auto-0, auto-k, etc.) based on last modified time
• Configurable timeouts - All timeouts adjustable via JupyterLab Settings
• Notifications - Optional toast notifications when resources are culled (requires jupyterlab-notifications)
• Server-side detection - Uses tornado PeriodicCallback for accurate activity tracking

Default Settings

| Setting | Default | Description | | ----------------- | ------------------ | --------------------------------------------------- | | Kernel timeout | 60 min (1 hour) | Idle kernels culled after this period | | Terminal timeout | 60 min (1 hour) | Inactive terminals culled after this period | | Disconnected only | enabled | Only cull terminals with no open browser tab | | Workspace culling | enabled | Cull stale workspaces (default workspace protected) | | Workspace timeout | 10080 min (7 days) | Stale workspaces culled after this period | | Check interval | 5 min | How often the culler checks for idle resources | | Notifications | enabled | Show notification when resources are culled |

How Idle Detection Works

Kernels: Checked for execution_state (busy kernels are never culled) and last_activity timestamp. A kernel is idle when it's not executing and hasn't had activity beyond the timeout.

Terminals: By default, only terminals with no active browser tab are culled (controlled by "Only Cull Disconnected Terminals" setting). When a terminal tab is open, it maintains a WebSocket connection and won't be culled regardless of idle time. Once the tab is closed, the terminal becomes eligible for culling after the idle timeout.

Workspaces: Based on the workspace file's last_modified timestamp. JupyterLab creates auto-named workspaces (auto-0, auto-k, etc.) when you open multiple windows. The default workspace is never culled.

Note: Terminal culling sends SIGHUP to the terminal process. Processes started with nohup will survive culling.

Installation

Requires JupyterLab 4.0.0 or higher.

pip install jupyterlab-kernel-terminal-workspace-culler-extension

Configuration

Open JupyterLab Settings (Settings -> Settings Editor) and search for "Resource Culler" to adjust timeouts and enable/disable culling for each resource type.

Logs

Culling actions are logged at INFO level with [Culler] prefix:

[Culler] CULLING KERNEL abc123 - idle 65.2 minutes (threshold: 60)
[Culler] Kernel abc123 culled successfully
[Culler] CULLING TERMINAL 1 - idle 62.1 minutes (threshold: 60)
[Culler] Terminal 1 culled successfully

Run JupyterLab with --log-level=INFO to see culling activity.

FAQ

Q: My long-running calculation was killed. How do I prevent this?

Two options:

1. Increase timeout: Go to Settings -> Settings Editor -> Resource Culler and increase the kernel/terminal timeout
2. Use a terminal multiplexer: Run calculations inside screen or tmux - these survive terminal culling

# Using screen
screen -S mysession
python long_calculation.py
# Detach with Ctrl+A, D

# Using tmux
tmux new -s mysession
python long_calculation.py
# Detach with Ctrl+B, D

Q: Will closing my browser tab kill my running process?

For terminals: By default, terminals are only culled when the browser tab is closed (disconnected). After closing the tab, the terminal will be culled once the idle timeout expires. Foreground processes receive SIGHUP. Use nohup, screen, or tmux for processes that must survive.

For kernels: The kernel continues running. Activity is tracked server-side, so a busy kernel won't be culled even if the browser is closed.

Q: What happens to processes started with nohup?

They survive terminal culling. nohup makes processes ignore SIGHUP, which is the signal sent when a terminal closes.

Q: How do I disable culling entirely?

Go to Settings -> Settings Editor -> Resource Culler and uncheck "Enable Kernel Culling" and "Enable Terminal Culling".

Q: Can I see when resources were culled?

Yes. Run JupyterLab with --log-level=INFO to see [Culler] log messages. If you have jupyterlab-notifications installed, you'll also see toast notifications.

CLI

The extension includes a command-line tool for listing and culling resources from the terminal.

# Show help
jupyterlab_kernel_terminal_workspace_culler

# List all resources and their idle times
jupyterlab_kernel_terminal_workspace_culler list

# List as JSON
jupyterlab_kernel_terminal_workspace_culler list --json

# Show what would be culled (dry run)
jupyterlab_kernel_terminal_workspace_culler cull --dry-run

# Cull idle resources
jupyterlab_kernel_terminal_workspace_culler cull

# Custom timeouts
jupyterlab_kernel_terminal_workspace_culler cull --kernel-timeout 30 --terminal-timeout 120

The CLI auto-discovers running Jupyter servers. You can also set environment variables:

• JUPYTER_SERVER_URL - server URL (e.g., http://localhost:8888/)
• JUPYTER_TOKEN - authentication token

Uninstall

pip uninstall jupyterlab-kernel-terminal-workspace-culler-extension