Interactive Tasks

Submit interactive tasks

An interactive task is a special queue task. In this mode, users can log in to a computing node directly, and all operations are performed on this node. This function is mainly convenient for users to debug the program on the server so that they can see the output of the program in real time.

You need to use the salloc command to allocate the resources needed for interactive tasks. Its syntax is:

$ salloc [Apply for resources]

You may specify the requested resource in the form of options, which are basically the same as those in the SLURM script. For example, you can apply for resources in the following ways:

user_name@Control:~$ salloc -N 1 --cpus-per-task=4 -t 5:00 -p CPU-Compute
salloc: Granted job allocation 411
user_name@Control:~$

After successful execution, SLURM will give you a new shell. Note that the node where the user is located is still the master node at this time. You need to manually switch to the compute node using the slink command:

user_name@Control:~$ salloc -N 1 --cpus-per-task=4 -t 5:00 -p CPU-Compute
salloc: Granted job allocation 2294
salloc: Waiting for resource configuration
salloc: Nodes Compute2030005001 are ready for job
use_name@Control:~slink
user_name@Compute2030005001:~$

As shown above, after executing salloc, SLURM automatically allocates the job number and informs which node is available. After successfully obtaining resources and login via the ssh, you get a new shell (Line 5). At this time, the user can directly switch to the target node comput1 to perform the computing task.

After the interactive calculation is completed, use exit to exit the node, and then execute exit to exit the shell allocated by SLURM to end this interactive task. SLURM will inform you that the resources of the interactive task have been released.

user_name@Compute2030005001:~$ exit                 # This step is to exit CPU-compute-1
exit
Connection to compute2030005003 closed.
user_name@Control:~$ exit
exit
salloc: Relinquishing job allocation 2294 # Resources are also released when exiting
user_name@Control:~$

Then, you will return to the Control node.

user_name@Control:~$ ssh Compute2030005001
Access denied: user user_name(uid=xxx) has no active jobs on this node.
Connection closed by Compute2030005001 port 22