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Comsol+Matlab on Linux cluster: "No user name and password could be obtained"

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A problem I had and its solution, for the record. (Just seeing as nobody reported these error messages yet.)


Just tried running Comsol+Matlab on a cluster, using what seemed to work before:

$ \comsol server -tmpdir $TMPDIR < /dev/null > test2016apr01.log &

But Matlab said: "No user name and password could be obtained" after I entered "mphstart()".

So it turned out that Comsol server collapsed, and the log file said:

Username: Username: Username: Username: Username: Username: Username: Username: Username: Username: Made_X_attempts_at_obtaining_user_name._Giving_up#10


The way around this that I found was to first run Comsol server as follows:

$ \comsol mphserver -tmpdir $TMPDIR

It will then ask for a username and password. Luckily, it remembers these for the next time it runs, because it's not possible to connect to the above (at least with the way our cluster is set up, and probably others). So, shutting it down and running as follows, now works:

$ \comsol server -tmpdir $TMPDIR < /dev/null > test2016apr01.log &

$ matlab

Now, the right directory needs to be added to Matlab's PATH. For me this is /usr/local/comsol/5.1/mli but for others it's likely to be different. There is probably a way to permanently store this somehow, but I haven't found it yet. Post if you have a way (this is on Linux; it's easy on Windows).

Now this works:

>> mphstart()


2 Replies Last Post 20.07.2016, 07:32 GMT-4
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist

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Posted: 8 years ago 01.04.2016, 22:44 GMT-4
Question: Is it correct that you need a separate MATLAB license for each node on the cluster that you are using ? Also, in distributed parallel mode, there is not a MATLAB equivalent of a floating network license such as in COMSOL. There is a parallel version of MATLAB, but it only works with shared-memory parallel. Are these statements correct ? Shed some light please.

Thanks
Question: Is it correct that you need a separate MATLAB license for each node on the cluster that you are using ? Also, in distributed parallel mode, there is not a MATLAB equivalent of a floating network license such as in COMSOL. There is a parallel version of MATLAB, but it only works with shared-memory parallel. Are these statements correct ? Shed some light please. Thanks

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Posted: 8 years ago 20.07.2016, 07:32 GMT-4
(Somehow I didn't get notified of your reply, and only saw it now.) That isn't a worry, because I don't know the answers to any of those questions.

Distributed makes good sense for Matlab, because a good fraction of everyday use cases are embarrassingly parallel. But I guess I haven't ran into anything requiring that sort of scale with Matlab so far...
(Somehow I didn't get notified of your reply, and only saw it now.) That isn't a worry, because I don't know the answers to any of those questions. Distributed makes good sense for Matlab, because a good fraction of everyday use cases are embarrassingly parallel. But I guess I haven't ran into anything requiring that sort of scale with Matlab so far...

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