Using tmux for Long-Running Computations
========================================

Introduction
------------

Scientific computations often run for hours or days.

Closing an SSH connection normally terminates the running process.

The recommended solution is to execute computations inside a tmux
session.

A tmux session continues running even after disconnecting from the
server.

Creating a Session
------------------

Create a new session:

.. code-block:: bash

   tmux new -s computation

The session name should describe the project or experiment.

Examples:

.. code-block:: text

   computation
   affine_rack
   classification
   homology
   experiment_01

Running a Computation
---------------------

After entering the session, start the computation:

.. code-block:: bash

   ~/gap-4.15.1/gap -m 120000m ~/PROJECTS/computation.g

The process continues running inside the tmux session.

Detaching from the Session
--------------------------

To leave the session without terminating the computation:

Press:

.. code-block:: text

   Ctrl+b d

The computation continues running in the background.

Listing Sessions
----------------

Show all sessions:

.. code-block:: bash

   tmux ls

Example output:

.. code-block:: text

   computation: 1 windows
   experiment_01: 1 windows

Reattaching to a Session
------------------------

Reconnect to a running session:

.. code-block:: bash

   tmux attach -t computation

This is the most frequently used command.

It allows monitoring the progress of long computations after logging
back into the server.

Monitoring a Running Computation
--------------------------------

After attaching, inspect:

* Program output.
* Log messages.
* Error messages.
* Progress indicators.

The computation continues exactly where it was left.

Terminating a Session
---------------------

When the computation has finished and the session is no longer needed:

.. code-block:: bash

   tmux kill-session -t computation

Use this command to clean up unused sessions and free resources.

Recommended Workflow
--------------------

A typical workflow is:

1. Connect to the server.
2. Create a tmux session.
3. Launch the computation.
4. Detach from the session.
5. Disconnect from the server.
6. Reconnect later.
7. Attach to the session.
8. Inspect the results.
9. Terminate the session when finished.

Example
-------

Create a session:

.. code-block:: bash

   tmux new -s affine_rack

Run GAP:

.. code-block:: bash

   ~/gap-4.15.1/gap -m 120000m ~/AFFINERACK/main.g

Detach:

.. code-block:: text

   Ctrl+b d

Reconnect later:

.. code-block:: bash

   tmux attach -t affine_rack

Terminate when finished:

.. code-block:: bash

   tmux kill-session -t affine_rack