January 10th, 2017 | Categories: HPC, parallel programming, RSE, Scientific Software, University of Sheffield | Tags:

I work at The University of Sheffield where I am one of the leaders of the new Research Software Engineering function. One of the things that my group does is help people make use of Sheffield’s High Performance Computing cluster, Iceberg.

Iceberg is a heterogenous system with around 3440 CPU cores and a sprinkling of GPUs. It’s been in use for several years and has been upgraded a few times over that period. It’s a very traditional HPC system that makes use of Linux and a variant of  Sun Grid Engine as the scheduler and had served us well.


A while ago, the sysadmin pointed me to a goldmine of a resource — Iceberg’s accounting log. This 15 Gigabyte file contains information on every job submitted since July 2009. That’s more than 7 years of the HPC usage of 3249 users — over 46 million individual jobs.

The file format is very straightforward. There’s one line per job and each line consists of a set of colon separated fields.  The first few fields look like something like this:


The username is field 4 and the number of slots used by the job is field 35. On our system, slots correspond to CPU cores. If you want to run a 16 core job, you ask for 16 slots.

With one line of awk, we can determine the maximum number of slots ever requested by each user.

gawk -F: '$35>=slots[$4] {slots[$4]=$35};END{for(n in slots){print n, slots[n]}}' accounting > ./users_max_slots.csv

As a quick check, I grepped the output file for my username and saw that the maximum number of cores I’d ever requested was 20. I ran a 32 core MPI ‘Hello World’ job, reran the line of awk and confirmed that my new maximum was 32 cores.

There are several ways I could have filtered the number of users but I was having awk lessons from David Jones so let’s create a new file containing the users who have only ever requested 1 slot.

gawk -F: '$35>=slots[$4] {slots[$4]=$35};END{for(n in slots){if(slots[n]==1){print n, slots[n]}}}' accounting > users_where_max_is_one_slot.csv

Running wc on these files allows us to determine how many users are in each group

wc users_max_slots.csv 

3250  6498 32706 users_max_slots.csv

One of those users turned out to be a blank line so 3249 usernames have been used on Iceberg over the last 7 years.

wc users_where_max_is_one_slot.csv 
2393  4786 23837 users_where_max_is_one_slot.csv

That is, 2393 of our 3249 users (just over 73%) over the last 7 years have only ever run 1 slot, and therefore 1 core, jobs.

High Performance?

So 73% of all users have only ever submitted single core jobs. This does not necessarily mean that they have not been making use of parallelism. For example, they might have been running job arrays – hundreds or thousands of single core jobs performing parameter sweeps or monte carlo simulations.

Maybe they were running parallel codes but only asked the scheduler for one core. In the early days this would have led to oversubscribed nodes, possibly up to 16 jobs, each trying to run 16 cores.These days, our sysadmin does some voodoo to ensure that jobs can only use the number of cores that have been requested, no matter how many threads their code is spawning. Either way, making this mistake is not great for performance.

Whatever is going on, this figure of 73% is surprising to me!

Thanks to David Jones for the awk lessons although if I’ve made a mistake, it’s all my fault!

Update (11th Jan 2017)

UCL’s Ian Kirker took a look at the usage of their general purpose cluster and found that 71.8% of their users have only ever run 1 core jobs. https://twitter.com/ikirker/status/819133966292807680



December 31st, 2016 | Categories: Android | Tags:

A personal Android history

My first Android phone was the HTC Hero which I wrote about all the way back in 2009. It was very different to anything I’d had before and I liked it a lot. I even compared it to 1980s supercomputers in an article that subsequently got slashdotted. Android has changed a lot since then and I’ve kept up with most of the changes although I quickly switched to Samsung after the Hero. I started off with the Galaxy S1 but upgraded to the Galaxy S2 relatively quickly when the S1 died.  The S2 was a nice phone. I remember I liked that one a lot.

I then switched to the Galaxy Note series of phones and was regularly mocked by my friends for owning such a HUGE phone; If I had a pound for every time someone referenced a particular Trigger Happy TV sketch I’d be a rich man!  The large screen was perfect for keeping me entertained on the regular train commute between Sheffield and Manchester that I endured at the time. The Note 1 gave way to the Note 2 followed by the  Note 3 — I upgraded fairly regularly back then.

Things are different now

For the first time since starting out with Android, I didn’t feel compelled to upgrade when the next version of my phone came out. The Note 4 passed me by and the next time I noticed a phone in the series was when my boss got the ill-fated Note 7.

Perhaps I’m just getting old but the truth is that my phone usage has stabilised around a few core applications — none of which require anything too fancy. Although I use my phone heavily, I don’t do anything that pushes its capabilities. Reading (Kindle, Guardian, Browser), Video (iPlayer, Netflix, YouTube), Audio (Music, DoggCatcher, Audible) and social media (Gmail and Twitter) are probably my most used apps. Other than that, it’s predominantly utility-type stuff such as Calendar, Camera, Maps, Coursera, Calculator and so on.  A slew of things I fire up occasionally such as Fitbit and Shazam and that’s pretty much it.

In the early days of Android, I used to play a lot of games but no longer do so. This is primarily due to a lack of time but also because most mobile games simply aren’t fun anymore. The industry switch to the Fremium model has changed game dynamics in a way that I don’t find palatable.

The Note 3 wasn’t just good enough for my usage pattern, it was better than I needed it to be! I’m perfectly happy with the HD screen resolution of my 32inch TV so having the same resolution on a 5(ish) inch phone feels like decadent luxury. There’s an awesome stylus I never use, more CPU horse power than I need and a ton of sensors that I don’t have time to play with.

I don’t need to upgrade my phone anymore

As a Research Software Engineer I find that whatever computer I have is not quite good enough. I could always do with more cores, a faster clock speed, better GPU or more memory (No burning desire for dongles or a touch bar though!).  Phones are different. They got good enough for me years ago.

Breaking out of the phone upgrade treadmill is great: I can reduce my contract down to almost nothing and put the money saved from handset upgrades to something more important like financial independence.

So, when I lost my Note 3 and found myself back in the mobile phone market earlier this year, I was gutted!

My Big Android Mistake – The Samsung Galaxy S5 Neo

The logic went like this:

  • The Note 3 was good enough but I never used the stylus and modern galaxy note phones cost a fortune. They also explode!
  • All I need to do is find a phone that matches the Note 3 performance.
  • I can probably do that by getting a mid range phone these days — saving me money.
  • I’ll stick to Samsung since they’ve served me well so far.

I reminded myself of the Note 3 benchmarks and discovered that the S5 Neo had slightly better performance. This review told me that the S5 Neo had an AnTuTu Benchmark result of 37,854. When I ran this on my trusty Note 3, the score was 35,637.

The reviews for the S5 neo were reasonably good, it was several hundred pounds cheaper than flagships such as the Note 7 or the Galaxy edge and performance was on-par with my Note 3. So I got it.

Big Mistake! Huge!

Without a shadow of a doubt, the S5 Neo was the worst phone I’ve ever owned and I’ve been around! I’ve had Windows Mobile phones you understand…not the modern Windows Phone that no one uses but Ye-Olde Windows Mobile that was around when the iPhone was a twinkle in Steve Job’s eye.

It did this thing where I’d turn it on and before I could finish typing my 4 digit pin, it would switch itself off again. Bear in mind that I am not slow at doing this! It would do this randomly so that at the point where I hit peak rage, someone would come over to see why I’m so upset only for it to work perfectly when I showed them.

Everything lagged like nothing I’ve ever seen before. Messages about checking the back cover popped up randomly, apps crashed all the time; it was a frustrating experience! When I mentioned these problems at work, one of the PhD students said ‘S5 Neo? Oh yeah, my mom has that….Worst. Phone. Ever.’

A geek friend suggested that I flash the phone with cyanogenmod but there wasn’t an s5 Neo version. Woes!

Oddly, it seems to be very much a Marmite phone. Some people love it while others have had the same experience as me. This forum shows the love/hate divide quite nicely.

An attempt at destruction

A few days ago, the S5 Neo managed to push all my buttons and, having lost my temper with it, I threw it hard onto the floor….something I’ve never done with a mobile phone before. Unfortunately, I was in the living room and the phone bounced off the carpet and back into my hand. My attempt at its destruction was futile!

The ‘check battery cover’ message popped up.

Damn thing was taunting me!


The OnePlus 3T – A New Hope

Having a mobile phone that drives you to acts of rage against the machine is ridiculous so I vowed to get rid of it that day. First step — find a new phone. A better phone. Ideally, one that didn’t break the bank.

I saw a review of the OnePlus 3T that looked great! A search through various forums and twitter suggested that this was a good, alternative choice. I couldn’t see a downside so I took the plunge. It cost around £450 pounds upfront and unlocked from 02 but they also gave me £55 for scrap value of the S5 Neo.

Just over a week later, I can report that I am very happy so far. This appears to be the Android phone I’ve been looking for!

Review articles and benchmarks coming in the new year.

December 12th, 2016 | Categories: Open Data Science, RSE, Scientific Software | Tags:

I was in Stockholm last week to give an invited talk at the Workshop on Nordic Big Biomedical Data for Action. I was representing the Software Sustainability Institute and delivered the latest version of my talk Is Your Research Software Correct? screen-shot-2016-12-11-at-12-47-14

It was a great event which introduced me to some nice initiatives going on waaaay up north. Initiatives such as Code Refinery who’s aims align well with those of the UK’s software sustainability Institute. Code refinery was introduced by Radovan Bast — Slide deck at http://cicero.xyz/v2/remark/github/coderefinery/talk-intro/niasc-2016/talk.md/#1


Other talks included the introduction of a scalable, parallel version of BLAST, Big Data Processing for Genomics and Delivering Bioinformatics Software as Virtual Machine images. I also got chance to geek out with some High Performance Computing and Bioinformatics people over interesting Swedish food.

Slides from most of the talks are available at http://www.nordicehealth.se/2016/12/04/workshop-on-nordic-big-biomedical-data-for-action/

October 13th, 2016 | Categories: math software, R, RSE, Scientific Software, University of Sheffield | Tags:

I was recently invited to give a talk at the Sheffield R Users Group and decided to give a brief overview of how R relates to other technologies. Subjects included Mathematica’s integration of R, Intel’s compilers, Math Kernel Library and how they can make R faster and a range of Microsoft technologies including R Tools for Visual Studio, Microsoft R Open and the MRAN for reproducibility. I also touched upon the NAG Library, Maple’s code generation for R, GPUs and Spark.

Did I miss anything? If you were to give a similar talk, what might you have included?

September 22nd, 2016 | Categories: RSE | Tags:

“It gives me great pleasure to welcome you all to the first ever Research Software Engineering conference” 

Rob Haines‘ opening line was met by thunderous applause from 202 people representing 14 different countries with a delegation that included funders, industry, academic researchers and, of course, research software engineers. The hairs on the back of my neck stood up as it dawned on me that this was a historic moment and that I was there when it happened. I wasn’t the only one


I felt like I’d come home and that these people were my tribe…and what a tribe!


Microsoft loves Linux

The conference was a mixture of talks, workshops and networking opportunities with the opening plenary given by Matthew Johnson of Microsoft Research. Microsoft was the gold sponsor for the event and the swag bag included one of these

we're not in Kansas anymore

I reflect on the fact that I’m currently using my Macbook Pro as a Windows 10 machine to access the linux subsystem — we’re not in Kansas anymore!

Microsoft is a keen supporter of the RSE movement although the job title they use is ‘Research Software Development Engineer’, a title they’ve used for several years now. An RSE (or RSDE) does much more software development than a typical researcher and more research than a typical software engineer.

The choice of job role is important since it defines how you are assessed for things such as promotion. This is an issue that some of us are working to address within academia because many RSEs are currently assessed using the same criteria as researchers.


Docker…we need more Docker

The conference included several practical workshops on all sorts of interesting topics but the most popular, by far, was the Docker workshop. It was so oversubscribed that access to the room had to be strictly controlled! Even I wasn’t allowed in and I was on the organising committee!

Fortunately, the materials are freely available on github – https://github.com/mfernandes61/RSE_Docker_course/wiki 


What a diff’rence a fellowship makes

I attended a discussion workshop called ‘The Role of the Research Software Engineer’ and gave a caffeine fueled lighting talk about the impact my EPSRC RSE fellowship has had within the University of Sheffield over its first six months. Slides are at https://mikecroucher.github.io/fellowship_difference/ but you might not get much from them since I like to talk over a set of images for things like this.

The EPSRC RSE Fellowship is the first of its kind and I believe that its had a huge impact on how the role of RSE is perceived by academic institutions. There were only 7 awards, however, so there is still so much more to be done.

Since members of the audience included representatives from various funding bodies, I wanted to help convince them that RSE fellowships are great value for money and they should consider launching their own.

Workshop materials

Here is a list of links to some of the workshop materials. If you know of one I’ve missed, please let me know.


For more information about what happened on the day see the following links

September 5th, 2016 | Categories: Open Data Science, RSE, Science, Scientific Software, tutorials, University of Sheffield | Tags:

One of the great things about being a Research Software Engineer is the diversity of work you can get involved with. I specialise in smaller interventions which means that I can be working with physicists on Monday, engineers on Tuesday, geneticists on Wednesday….you get the idea.

Last month, I got to work with some Ecologists along with Anna Krystalli. We undertook the arduous journey from Sheffield down to Exeter to deliver talks and workshops at a post-conference symposium on reproducibility in science, organised by Malika Ihle and Isabel Winney, at the International Symposium on Behavioural Ecology.

I gave my talk, Is your research software correct?, and also delivered a workshop on using projects and version control using R and RStudio in the Code Cafe style. For the full write up of the day, see the excellent blog post by Anna over at the Mozilla Science Lab blog.

Updates : More resources

August 24th, 2016 | Categories: programming, RSE | Tags:

I sometimes give a talk called Is Your Research Software correct (github repo, slide deck) where I attempt to give a (hopefully) entertaining overview of some of the basic issues in modern research software practice and what can be done to make the world a little better.

One section of this talk is a look at some case studies where software errors caused problems in research. Ideally, I try to concentrate on simple errors that led to profound scientific screw-ups. I want the audience to think ‘Damn! *I* could have made that mistake in my code‘.

Curating this talk has turned me into an interested collector of such stories. This is not an exercise in naming and shaming (after all, the odds are that its only a matter of time before I, or one of my collaborators, makes it into the list — why set myself up for a beating?). Instead, it is an exercise in observing the problems that other people have had and using them to enhance our own working practices.

Thus begins a new recurring WalkingRandomly feature.

Excel corrupts genetics data

Today’s entry comes courtesy of a recent paper by Mark Ziemann, Yotam Eren and Assam El-OstaEmail – ‘Gene name errors are widespread in the scientific literature‘ where they demonstrate that the supplementary data files for hundreds of papers in genetics have been corrupted by Microsoft Excel which has helpfully turned gene symbols into dates and floating point numbers.

The paper gives advice to reviewers on how to spot this particular error and the authors have also published the code used for the analysis. I’ve not run it myself so can only attest to its existence, not it’s accuracy.

I’ve not dealt with genetic data directly myself so ask you — what would you have used instead of Excel? (my gut tells me R or Python but I have no details to offer).

Do you have a story to contribute?

If you are interested in contributing a story where a software glitch caused problems in research, please contact me to discuss details.

Update (31st August 2016)

One of the authors of the paper, Mark Ziemann, has written a follow up of the Excel work on his blog: http://genomespot.blogspot.co.uk/2016/08/my-personal-thoughts-on-gene-name-errors.html

August 11th, 2016 | Categories: programming, python | Tags:

This is my rant on import *. There are many like it, but this one is mine.

I tend to work with scientists so I’ll use something from mathematics as my example.  What is the result of executing the following line of Python code?

result = sqrt(-1)

Of course, you have no idea if you don’t know which module sqrt came from. Let’s look at a few possibilities. Perhaps you’ll get an exception:

In [1]: import math
In [2]: math.sqrt(-1)
ValueError Traceback (most recent call last)
in ()
----> 1 math.sqrt(-1)

ValueError: math domain error

Or maybe you’ll just get a warning and a nan

In [3]: import numpy
In [4]: numpy.sqrt(-1)
/Users/walkingrandomly/anaconda/bin/ipython:1: RuntimeWarning: invalid value encountered in sqrt
#!/bin/bash /Users/walkingrandomly/anaconda/bin/python.app
Out[4]: nan

You might get an answer but the datatype of your answer could be all sorts of strange and wonderful stuff.

In [5]: import cmath
In [6]: cmath.sqrt(-1)
Out[6]: 1j
In [7]: type(cmath.sqrt(-1))
Out[7]: complex

In [8]: import scipy
In [9]: scipy.sqrt(-1)
Out[9]: 1j
In [10]: type(scipy.sqrt(-1))
Out[10]: numpy.complex128

In [11]: import sympy
In [12]: sympy.sqrt(-1)
Out[12]: I
In [13]: type(sympy.sqrt(-1))
Out[13]: sympy.core.numbers.ImaginaryUnit

Even the humble square root function behaves very differently when imported from different modules! There are probably other sqrt functions, with yet more behaviours that I’ve missed.

Sometimes, they seem to behave in very similar ways:-

In [16]: math.sqrt(2)
Out[16]: 1.4142135623730951

In [17]: numpy.sqrt(2)
Out[17]: 1.4142135623730951

In [18]: scipy.sqrt(2)
Out[18]: 1.4142135623730951

Let’s invent some trivial code.

from scipy import sqrt

x = float(input('enter a number\n'))
y = sqrt(x)

# important things happen after here. Complex numbers are fine!

I can input -1 just fine. Then, someone comes along and decides that they need a function from math in the ‘important bit’. They use import *

from scipy import sqrt
from math import *

x = float(input('enter a number\n'))
y = sqrt(x)

# important things happen after here. Complex numbers are fine!

They test using inputs like 2 and 4 and everything works (we don’t have automated tests — we suck!). Of course it breaks for -1 now though. This is easy to diagnose when you’ve got a few lines of code but it causes a lot of grief when there’s hundreds…or, horror of horrors, if the ‘from math import *’ was done somewhere in the middle of the source file!

I’m sometimes accused of being obsessive and maybe I’m labouring the point a little but I see this stuff, in various guises, all the time!

So, yeah, don’t use import *.

August 5th, 2016 | Categories: Linux, tutorials, Windows | Tags:

Like many people, I was excited to learn about the new Linux subsystem in Windows announced by Microsoft earlier this year (See Bash on Windows: The scripting game just changed).

Along with others, I’ve been playing with it on the Windows Insider builds but now that the Windows Anniversary Update has been released, everyone can get in on the action.

Activating the Linux Subsystem in Windows

Once you’ve updated to the Anniversary Update of Windows, here’s what you need to do.

Open settings


In settings, click on Update and Security


In Update and Security, click on For developers in the left hand pane. Then click on Developer mode.


Take note of the Use developer features warning and click Yes if you are happy. Developer mode gives you greater power, and with great power comes great responsibility.


Reboot the machine (may not be necessary here but it’s what I did).

Search for Features and click on Turn Windows features on or off


Tick Windows Subsystem for Linux (Beta) and click OK

Screen Shot 2016-08-05 at 15.30.08

When it’s finished churning, reboot the machine.

Launch cmd.exe

Screen Shot 2016-08-05 at 15.36.14

Type bash, press enter and follow the instructions

Screen Shot 2016-08-05 at 15.37.58

The linux subsystem will be downloaded from the windows store and you’ll be asked to create a Unix username and password.

Try something linux-y

The short version of what’s available is ‘Every userland tool that’s available for Ubuntu’ with the caveat that anything requiring a GUI won’t work.

This isn’t emulation, it isn’t cygwin, it’s something else entirely. It’s very cool!

The gcc compiler isn’t installed by default so let’s fix that:

sudo apt-get install gcc

Using your favourite terminal based editor (I used vi), enter the following ‘Hello World’ code in C and call it hello.c.

/* Hello World program */


int main()
    printf("Hello World from C\n");

Compile using gcc

gcc hello.c -o hello

Run the executable

Hello World from C

Now, transfer the executable to a modern Ubuntu machine (I just emailed it to myself) and run it there.

That’s right – you just wrote and compiled a C-program on a Windows machine and ran it on a Linux machine.

Now install cowsay — because you can:

sudo apt-get install cowsay
cowsay 'Hello from Windows'
< Hello from Windows >
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Update 1:

I was challenged by @linuxlizard to do a follow up tutorial that showed how to install the scientific Python stack — Numpy, SciPy etc.

It’s all there :)

sudo apt-get install python-scipy

Screen Shot 2016-08-05 at 16.42.30

Update 2

TensorFlow on LinuxOnWindows is also easy: http://www.hanselman.com/blog/PlayingWithTensorFlowOnWindows.aspx

July 27th, 2016 | Categories: RSE | Tags:

This post is also published over at the Software Sustainability Institute.

William Stein, lead developer of the computer algebra system, Sage, and its cloud-based spin-off, SageMathCloud, recently announced that he was quitting academia to go and form a company. In his talk, William says ‘I can’t figure out how to create Sage in academia. The money isn’t there. The mathematical community doesn’t care enough. The only option left is for me to build a company.’

His talk is below and slides are at http://wstein.org/talks/2016-06-sage-bp/bp.pdf


“Every great open source math library is built on the ashes of someone’s academic career.”

William’s departure is not unique. Here’s a tweet from Wes Mckinney, creator of pandas, one of the essential data science tools for Python.

Contact us

We are looking for similar stories; good research software people who felt that they had to leave academia because there wasn’t enough support, recognition or funding. Equally, we want to hear from you if you think academia is a rewarding environment for software development. Either way, please contact us at rse-study@software.ac.uk