Testing With Graphics
If you need to use graphics while testing your code on a Niagara compute node, e.g. when using a debugger such as DDT or DDD, you have the following options.
Use the debugjob command
You can use the
debugjob command, which automatically provides X-forwarding support.
$ ssh niagara.scinet.utoronto.ca -X USER@nia-login07:~$ debugjob debugjob: Requesting 1 nodes for 60 minutes xalloc: Granted job allocation 189857 xalloc: Waiting for resource configuration xalloc: Nodes nia0030 are ready for job [USER@nia1265 ~]$
Use the regular queue
debugjob is not suitable for your case due to the limitations either on time or resources (see Testing, then you must follow these steps. You will need two terminals in order to achieve this:
- In the 1st terminal:
- ssh to
niagara.scinet.utoronto.caand issue your
- wait until your resources are allocated and you are assigned the nodes
- take note of the node where you are logged to, ie. the head node, let's say
$ ssh niagara.scinet.utoronto.ca USER@nia-login07:~$ salloc --nodes 5 --time=2:00:00 .salloc: Granted job allocation 141862 .salloc: Waiting for resource configuration .salloc: Nodes nia1265 are ready for job [USER@nia1265 ~]$
- ssh to
- In the second terminal:
- ssh into
niagara.scinet.utoronto.canow using the
-Xflag in the ssh command.
- After that,
ssh -X niaWXYZ, ie. you will ssh carrying on the '-X' flag into the head node of the job.
- In the
niaWXYZyou should be able to use graphics and should be redirected by X-forwarding to your local terminal.
ssh niagara.scinet.utoronto.ca -X USER@nia-login07:~$ ssh -X nia1265 [USER@nia1265 ~]$ xclock ## just an example to test the graphics, a clock should pop up, close it to exit [USER@nia1265 ~]$ module load ddt ## load corresponding modules, eg. for DDT [USER@nia1265 ~]$ ddt ## launch DDT, the GUI should appear in your screen
- ssh into
- If you are using SSH from a Windows machine, you need to have an X-server, a good option is to use MobaXterm, that already brings an X-server included. See the [[ Windows SSH entry for other options.
- If you are in Mac OS, substitute -X by -Y
- Instead of using two terminals, you could just use
screento request the resources and then detach the session and ssh into the head node directly.