jupyterlab-kernel-terminal-workspace-culler-extension 1.0.3

Jupyterlab extension to kill unused kernels, terminals and workspaces. User can configure the idle time (minutes) after which the resource will be released automatically. This helps with the locked memory, insane number of terminals opened etc.

jupyterlab_kernel_terminal_workspace_culler_extension

Automatically cull idle kernels, terminals, and sessions after configurable timeout periods. Helps manage system resources by cleaning up unused sessions 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
• Session culling - Remove stale sessions based on associated kernel activity
• 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
Session timeout	10080 min (7 days)	Idle sessions 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: Based on WebSocket activity. If the browser tab is closed, activity stops being recorded even if the terminal process is running. For long-running jobs, use nohup, screen, or tmux.

Sessions: Based on the associated kernel's last_activity.

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: The terminal will be culled after the timeout since WebSocket activity stops when the browser closes. 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.

Uninstall

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