All posts by paramagnetic

Music for Monday

I watched MASH (the film, not the TV series) over the weekend, and it reminded me of the TV show, and its haunting theme. There appears to be some debate over the lyrics and their meanings (which there always will be for all songs, I think) but I think they’re clear enough, even if I personally disagree.

However, perhaps having a Music post focussed on a song about suicide (whether going through with it or not) is not the best idea…

So instead we’ll have some bagpipe music!

I will always love a good set of Pipes & Drums. Some of my favourite memories as a child was going to see the Edinburgh Military Tattoo (although I’ve got less keen of late, as less and less of the Pipes & Drums are actually the focus…)

Bagpipes are, ultimately, a war instrument. They were designed to scare the living Hell out of the opponents while you were still a ways away… because a demoralised opponent won’t fight as hard. But bagpipes can break 122dB… that is about as loud as a jet engine at takeoff…

…they’re still amazing, though.

Apocryphal or Not…

…we certainly appear to live in “interesting times”.

More’s the pity.

I can’t really say “I woke up to”, since I’m 8-hours ahead and watched the numbers roll in on the BBC (which while a little slower compared to some of the news sites – and on several occasions updated, only to revert a couple of minutes later, remains one of the best places for UK Election updates) but I don’t think this was the plan.

If I was a betting man – I’m not – I’d be thinking about putting some money down on exact when a leadership challenge is mounted. For now, I’ll say within the next two weeks.

Music for Monday

So, here we are again.

Another week, another Music for Monday. And various other things that have happened as well. I promised myself that I would not discuss politics or current events on this blog, lest I find that it be all I comment on. Nevertheless, I find myself half-amazed at the willful blindness and stupidity of those who should know better, and half enraged at that same blindness and stupidity.

But that is all I shall say on the matter. There may yet be a time in the future where I find myself going back on my promise to myself, re: politics and current events, but that day is not today.

I discovered Disturbed more or less by accident not all that long ago. Then I realised that they (or, rather, David Draiman) wrote some of the music for a film my friends dragged me to years ago.

I find I have been reading poetry of late…

…which, of course, most of those who know me fairly well find my patience for poetry to be… how shall I put this? Minimal.

Yes, minimal works quite well. I can appreciate it, I just rarely have time for it.

But Rudyard Kipling has, once more, drawn my attention.

Normally, for an author that old (thus whose books are well, well out of Copyright) I would direct any reader to Project Gutenberg but while they have many of his books, they appear to lack any significant collections of his poetry.

Thus, I am forced to provide a link to Kindle, however there are many options, ranging from astonishingly well priced (49p) into a price territory that makes me wonder if the publisher has actually looked at competing works.

ORCA & OpenMPI: File Descriptor Limits

I’ve just been tinkering around with an interesting issue: ORCA, the computational chemistry program I’ve been using because I can’t afford Gaussian, crashes during geometry optimisation of a (moderately) complex molecule because of OpenMPI.

OpenMPI is complaining about running out of file descriptors. Eh? Seriously? OK…

Turns out that Ubuntu 16.04 (even the server version) sets the open file limit at what is frankly a little on the low side – 1024 open files. That sounds like a lot, until you think that when running something via MPI it can be crunching across¬†a lot of temporary files and so on… and it suddenly doesn’t seem so many. Interestingly, I never had this problem before because I was running Ubuntu 14.04 previously which (from what the internet says) had a limit of 4096. I checked with the latest release (14.04.5) which had a limit of 1024, so I’ll assume for now that the 4096 limit was in an older release…

I’ll be honest, since this is the first time I’ve encountered this issue, I’ve never actually checked previously…

Anyway, there appear to be two fixes that work, one on a per-user basis, one on a system-wide basis. Pick your poison.

The user-level fix is super easy, add the following to your .bashrc:

if [ $USER = "paramagnetic" ]; then
ulimit -n [pick-a-big-number, eg; 32768]
fi

Can also be added to /etc/profile

At the system level, it’s a little more difficult, but still totally doable. Edit /etc/security/limits.conf

* soft nofile 32768
* hard nofile 32768
root soft nofile32768
root hard nofile 32768

Then add:

session required pam_limits.so

To /etc/pam.d/common-sessions and /etc/pam.d/common-sessions-noninteractive

And reboot in all cases. If you have another form of system management software running, it might overrule you, which is annoying, but outside of the scope of this post.