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Restart the BEC server

Overview

Restart the BEC service stack either from a terminal on the BEC host or directly from an active BEC IPython client.

Prerequisites

  • No scan or other critical acquisition is currently running.
  • You know which machine runs the BEC services.
  • If you restart from a terminal, you can log in to that machine and activate the correct Python environment.
  • If you restart from the client, you already have a working BEC IPython client session.

Restart only when BEC is idle

Restarting the server interrupts the running services and briefly disconnects clients. Do not restart BEC while scans, device motions, or file writing are still active.

1. Choose the restart method

Use this path when you already have an active BEC client session and do not want to open a second terminal on the BEC host.

From the BEC prompt, run:

%server_restart

Use this path when you want to restart BEC directly on the machine that runs the services. It is the only option if the server is not responding or it is not running yet.

If BEC runs on a remote VM or server, open a shell on that machine first:

ssh <user>@<bec-vm-host>

cd to the directory where the BEC services are installed. The exact path depends on your setup:

cd /sls/<xname>/config/bec/<deployment_name>

Activate the Python environment that provides the BEC commands.

source ./bec_venv/bin/activate

ssh personal_u@x99sa-bec-001.psi.ch

cd to the directory where the BEC services are installed. The exact path depends on your setup:

cd /sls/x99sa/config/bec/production

Activate the Python environment that provides the BEC commands.

source ./bec_venv/bin/activate

Then restart the BEC services:

bec-server restart

This stops the running services and starts them again with the currently installed code and configuration.

If you want to inspect the stack after the restart, you can attach to the running services:

bec-server attach

2. Wait for the services to come back

After the restart command, give the services a moment to come back up.

If you restarted from the IPython client, the client may briefly lose its connection while the services restart. Wait for the connection to recover, or reopen the client if needed.

3. Verify that BEC is ready again

Once the restart is complete, confirm that the server and client are usable again with a small check from the BEC prompt:

dev.show_all()

You can also verify that your intended change was picked up, for example by checking that a new scan, device configuration, or plugin behavior is now available.

Congratulations!

You can now restart the BEC server either from the host terminal with bec-server restart or from the BEC IPython client with %server_restart.

Common pitfalls

  • Restarting while an acquisition is still running.
  • Running bec-server restart on the wrong machine.
  • Forgetting to activate the Python environment before calling bec-server.
  • Expecting the IPython client to stay responsive during the short restart window.