If you wish to run interactively but are constrained by the limits on the CPUs, CPU Time or memory, you may run a small interactive job requesting the resources you want.

By doing that, you will get a dedicated allocation of CPUs and memory to run your application interactively. There are several ways to do this, depending on your use case:

Using srun directly

If you have a single script or a command you wish to run interactively, one way to do this through the batch system is with a direct call to srun from within session in the login node. It would feel as if you were running locally, but it is instead using a job with dedicated resources:

$ cat myscript.sh 
#!/bin/bash
echo "This is my super script"
echo "Doing some heavy work on $HOSTNAME..."
$ ./myscript.sh 
This is my super script
Doing some heavy work on at1-11...
$ srun ./myscript.sh 
This is my super script
Doing some heavy work on at1-105...

In that example the submitted job would have run using the default settings (default qos, with just 1 cpu and default memory). You can of course pass additional options to srun to customise the resources allocated to this interactive job. For example, to run with 4 cpus, 12 GB with a limit of 6 hours:

$ srun -c 4 --mem=12G -t 06:00:00 ./myscript.sh

Check man srun for a complete list of options.

Persistent interactive job with ecinteractive

However, you may want to To facilitate that task, we are providing the ecinteractive tool. Its main features are the following:

Only one interactive job is allowed at a time
Your job keeps on running after you exit the interactive shell, so you can reattach to it any time or open multiple interactive shells within the same job.
You may open a basic graphical desktop for X11 applications.
You may open a Jupyter Lab instance and connect to it through your browser.
By default it will submit to AA, but you can choose what complex (platform) to use.
You can run ecinteractive from any Atos HPCF complex, Red Hat Linux VDI. You may also copy the script to your end user device and use it from there. It should work from Linux, Mac, or WSL under windows, and requires the Teleport tsh client to be installed.

$ ecinteractive -h
Usage :  /usr/local/bin/ecinteractive [options] [--]

    -d|desktop     Submits a vnc job (default is interactive ssh job)
    -j|jupyter     Submits a jupyter job (default is interactive ssh job)

    More Options:
    -h|help        Display this message
    -v|version     Display script version
    -p|platform    Platform (default aa. Choices: aa, ab, ac, ad)
    -u|user        ECMWF User (default user)
    -A|account     Project account
    -c|cpus        Number of CPUs (default 2)
    -m|memory      Requested Memory (default 8G)
    -s|tmpdirsize  Requested TMPDIR size (default 3 GB)
    -t|time        Wall clock limit (default 06:00:00)
    -k|kill        Cancel any running interactive job
    -q|query       Check running job
    -o|output      Output file for the interactive job (default /dev/null)
    -x             set -x

Creating an interactive job

You can get an interactive shell running on an allocated node within the Atos HCPF with just calling ecinteractive. By default it will just use the default settings which are:

Cpus	2
Memory	8 GB
Time	6 hours
TMPDIR size	3 GB

If you need more resources, you may use the ecinteractive options when creating the job. For example, to get a shell with 4 cpus and 16 GB or memory for 12 hours:

[user@aa6-100 ~]$ ecinteractive -c4 -m 16G -t 12:00:00
Submitted batch job 10225018
Waiting 5 seconds for the job to be ready...
Using interactive job:
CLUSTER JOBID       STATE       EXEC_HOST  TIME_LIMIT  TIME_LEFT MAX_CPUS MIN_MEMORY TRES_PER_NODE
aa      10225018    RUNNING     aa6-104      12:00:00   11:59:55        4        16G     ssdtmp:3G

To cancel the job:
        /usr/local/bin/ecinteractive -k

Last login: Mon Dec 13 09:39:09 2021
[ECMWF-INFO-z_ecmwf_local.sh] /usr/bin/bash INTERACTIVE on aa6-104 at 20211213_093914.794, PID: 1736962, JOBID: 10225018
[ECMWF-INFO-z_ecmwf_local.sh] $SCRATCH=/ec/res4/scratch/user
[ECMWF-INFO-z_ecmwf_local.sh] $PERM=/ec/res4/perm/user
[ECMWF-INFO-z_ecmwf_local.sh] $HPCPERM=/ec/res4/hpcperm/user
[ECMWF-INFO-z_ecmwf_local.sh] $TMPDIR=/etc/ecmwf/ssd/ssd1/tmpdirs/user.10225018
[ECMWF-INFO-z_ecmwf_local.sh] $SCRATCHDIR=/ec/res4/scratchdir/user/8/10225018
[ECMWF-INFO-z_ecmwf_local.sh] $_EC_ORIG_TMPDIR=N/A
[ECMWF-INFO-z_ecmwf_local.sh] $_EC_ORIG_SCRATCHDIR=N/A
[ECMWF-INFO-z_ecmwf_local.sh] Job 10225018 time left:   11:59:54
[user@aa6-104 ~]$

If you log out, the job continues to run until explicietly cancelled or reaching the time limit.

Reattaching to an existing interactive job

Once you have an interactive job running, you may reattach to it, or open several shells within that job calling ecinteractive again.

If you have a job already running, ecinteractive will always attach you to that one regardless of the resources options you pass. If you wish to run a job with different settings, you will have to cancel it first

[user@aa6-100 ~]$ ecinteractive 
Using interactive job:
CLUSTER JOBID       STATE       EXEC_HOST  TIME_LIMIT  TIME_LEFT MAX_CPUS MIN_MEMORY TRES_PER_NODE
aa      10225018    RUNNING     aa6-104      12:00:00   11:57:56        4        16G     ssdtmp:3G

WARNING: Your existing job 10225018 may have a different setup than requested. Cancel the existing job and rerun if you with to run with different setup

To cancel the job:
        /usr/local/bin/ecinteractive -k

Last login: Mon Dec 13 09:39:14 2021 from aa6-100.bullx
[ECMWF-INFO-z_ecmwf_local.sh] /usr/bin/bash INTERACTIVE on aa6-104 at 20211213_094114.197, PID: 1742608, JOBID: 10225018
[ECMWF-INFO-z_ecmwf_local.sh] $SCRATCH=/ec/res4/scratch/user
[ECMWF-INFO-z_ecmwf_local.sh] $PERM=/ec/res4/perm/user
[ECMWF-INFO-z_ecmwf_local.sh] $HPCPERM=/ec/res4/hpcperm/user
[ECMWF-INFO-z_ecmwf_local.sh] $TMPDIR=/etc/ecmwf/ssd/ssd1/tmpdirs/user.10225018
[ECMWF-INFO-z_ecmwf_local.sh] $SCRATCHDIR=/ec/res4/scratchdir/user/8/10225018
[ECMWF-INFO-z_ecmwf_local.sh] $_EC_ORIG_TMPDIR=N/A
[ECMWF-INFO-z_ecmwf_local.sh] $_EC_ORIG_SCRATCHDIR=N/A
[ECMWF-INFO-z_ecmwf_local.sh] Job 10225018 time left:   11:57:54
[user@aa6-104 ~]$

Checking the status of a running interactive job

You may query ecinteractive for existing interactive jobs, and you can do so from within or outside the job. It may be useful to see how much time is left

[user@aa6-100 ~]$ ecinteractive -q
CLUSTER JOBID       STATE       EXEC_HOST  TIME_LIMIT  TIME_LEFT MAX_CPUS MIN_MEMORY TRES_PER_NODE
aa      10225018    RUNNING     aa6-104      12:00:00   11:55:40        4        16G     ssdtmp:3G

Killing/Cancelling a running interactive job

Logging out of your interactive shells spawn through ecinteractive will not cancel the job. If you have finished working with it, you should cancel it with:

[user@aa6-100 ~]$ ecinteractive -k
cancelling job 10225018...
CLUSTER JOBID       STATE       EXEC_HOST  TIME_LIMIT  TIME_LEFT MAX_CPUS MIN_MEMORY TRES_PER_NODE
aa      10225018    RUNNING     aa6-104      12:00:00   11:55:34        4        16G     ssdtmp:3G
Cancel job_id=10225018 name=user-ecinteractive partition=inter [y/n]? y
Connection to aa-login closed.

Opening graphical applications within your interactive job

if you need to run graphical applications, you can do so through the standard x11 forwarding.

If running it from an Atos HPCF login node, make sure you have connected there with ssh -X and that you have a working X11 server on your end user device (i.e. XQuartz on MAC, MobaXterm, Xming or similar on Windows)
If running it from the Red Hat Linux VDI, it should work out of the box
If running it from your end user device, make sure you have a working X11 server on your end user device (i.e. XQuartz on MAC, MobaXterm, Xming or similar on Windows)

Alternatively, you may use ecinteractive to open a basic window manager running on the allocated interactive node, which will open a VNC client on your end to connect to the running desktop in the allocated node:

[user@aa6-100 ~]$ ecinteractive -d
Submitted batch job 10225277
Waiting 5 seconds for the job to be ready...
Using interactive job:
CLUSTER JOBID       STATE       EXEC_HOST  TIME_LIMIT  TIME_LEFT MAX_CPUS MIN_MEMORY TRES_PER_NODE
aa      10225277    RUNNING     aa6-104       6:00:00    5:59:55        2         8G     ssdtmp:3G

To cancel the job:
        /usr/local/bin/ecinteractive -k

Attaching to vnc session...
To manually re-attach:
        vncviewer -passwd ~/.vnc/passwd aa6-104:9598

Opening a Jupyter Lab instance

You can also use ecinteractive to open up a Jupyter Lab instance very easily:

[user@aa6-100 ~]$ ./ecinteractive -j
Using interactive job:
CLUSTER JOBID       STATE       EXEC_HOST  TIME_LIMIT  TIME_LEFT MAX_CPUS MIN_MEMORY TRES_PER_NODE
aa      10225277    RUNNING     aa6-104       6:00:00    5:58:07        2         8G     ssdtmp:3G

To cancel the job:
        ./ecinteractive -k

Attaching to Jupyterlab session...
To manually re-attach go to http://aa6-104.ecmwf.int:33698/?token=b1624da17308654986b1fd66ef82b9274401ea8982f3b747