All posts by Tim Anderson

linux, professional, tech, visual studio, web authoring

.NET P/Invoke on Azure App Service for Linux

I have an online bridge game in development (yes, still!) and it is written in ASP.NET Core with C#. One of the things that interests bridge players is called double-dummy analysis; this is where you look at what would be the best play in a game if you knew where all the cards were, whereas when actually playing bridge you only see your own cards and, during play, another hand called Dummy, so half the cards are hidden.

Double-dummy analysis is a solved problem and bridge programmers benefit from an open source library called DDS (Double Dummy Solver) written primarily by Bo Hagland and Soren Hein. This is a C++ DLL that can also be compiled for Linux and MacOS.

I wanted to integrate DDS into the bridge game in order to give players information at the end of a game including whether they were in the optimum contract and whether they beat the optimum score. I started by doing a new C# wrapper for DDS though borrowing from the work here. My version is 64-bit and wraps a few more functions. I compiled the native DLL for Windows and Linux using OpenMP for concurrency, which considerably improves performance (Boost is another option but I did not find much difference).

Note: the usual caveats about P/Invoke apply here. During one of my tests I actually crashed the container running the app. The ASP.NET developers do a lot of work to make the platform reliable, and doing P/Invoke may introduce instability.

I added my wrapper into the ASP.NET application and it worked fine on my development machine. I deployed it to App Service and the P/Invoke calls did not work. Fixing this required a bit of a deep dive into Azure App Service for Linux.

I am deploying the native code .so library into the same directory as the compiled .NET code for the rest of the application. The error I got was:

Cannot open shared object file: No such file or directory

I raised the topic on Stack Overflow.

One of the things that puzzled me was that the unit tests, which include the P/Invoke code, ran OK in Azure Pipelines, which I use for deployment. But not when deployed.

The first point is that you get the “No such file” error not only when the file itself is not present (it was) but also when a dependency is missing. So step one is to SSH into the container running the ASP.NET app, which you can do with the Development Tools in the Azure portal. Note that with Azure App Service for Linux the app always runs in a container.

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This gives you root permissions in the container though not to the host operating system. Navigate to the directory with the troublesome library and type:

ldd libdds.so

(or the name of your library). This will tell you if any dependencies are missing or other issues. I noticed two things. One is that it was missing the dependency libgomp.so.1 which is the OpenMP library. Second, ldd reported that my library required at least GLIBC 2.29 where the available version was 2.28.

How could I fix the GLIBC version? This is determined by the version of Linux and you can use

ldd – version

to check the version you have. In my case it said I had Debian with GLIBC 2.28:

image

I did some more research. If you really want to know about Azure App Service for Linux, there are a few key documents.

The basics here: Operating system functionality – Azure App Service | Microsoft Learn

The FAQ here: App Service on Linux FAQ | Microsoft Learn

Here you will learn details like why you cannot use a file-based database like SQLite in Azure App Service for Linux:

“The file system of your application is a mounted network share. This enables scale out scenarios where your code needs to be executed across multiple hosts. Unfortunately this blocks the use of file-based database providers like SQLite since it’s not possible to acquire exclusive locks on the database file.”

But I digress. To go deeper still, check this post by Jim Cheshire:

Things You Should Know: Web Apps and Linux – Microsoft Tech Community

which has lots of critical information, like why a custom container on App Service must respond to ping.

So after reading through all this and greatly improving my understanding of how App Service for Linux works, I got to the heart of my problem. When you deploy a .NET Core application to App Service for Linux, it will by default use a container from the Microsoft Artifact Registry that matches the version of .NET you are using. If you check this page you will see that the current version for ASP.NET Core 6.0 is tagged mcr.microsoft.com/dotnet/aspnet:6.0

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If you examine this container you will find that it runs Debian Buster which uses GLIBC 2.28. It is a matter of slight concern since Debian Buster is shown on the Debian releases wiki as having an approximate end of life August 2022, though the LTS project extends that to June 2024.

Still, now I knew how to fix my problem. Either use a custom container image, or upgrade to .NET 7, or recompile libdds.so to run on Debian Buster.

I decided that the easiest short-term solution was to recompile. I downloaded Buster and recompiled the library.

What about libgomp.so.1? This was kind-of fixable by using SSH to run:

apt-get update

apt-get install libgomp1

This is not great though since Azure could replace the container at any time, and always if you do something like scale the plan up or down, to change the specification of the VM. I tried copying the buster version of libgomp.so.1 to the application directory. It works, but I also needed to add a linker option to enable DDS to use a library in the same directory:

 -Wl,-rpath='${ORIGIN}'

as explained here.

I think a better solution is to move to deploying a custom container to App Service, which is an option:

image

Care is needed though as there is a bit of special sauce in the official container images if you want features like SSH in the portal to work properly. It also means revisiting my deployment scripts, so the above hack was an easier and quicker workaround for me.

azure, microsoft, software development, tech

Microsoft to remove Azure “Basic” IP number and load balancer in favour of pricier options

Microsoft is removing some features from Azure which were called “Basic,” in favour of alternatives which have more features but are also more expensive.

A load balancer is a network component which balances traffic to virtual machines. The Basic load balancer is free but has a few limitations, such as no compatibility with availability zones, support for only 300 instances, no SLA (Service Level Agreement), and no support for NAT Gateway. Microsoft has emailed customers saying:

On 30 September 2025, Azure Basic Load Balancer will be retired. You can continue to use your existing Basic Load Balancers until then, but you’ll no longer be able to deploy new ones after 31 March 2025.

The Standard load balancer routes to availability zones, supports up to 5000 instances, is secure by default, and has a 99.9% SLA, but it costs $0.025 per hour, or around $18 per month, for up to 5 rules.

A Basic public IP number costs  $0.0036 per hour or about $2.60 per month. It is a perfectly good IP number but does not support zone resiliency. A standard public IP number costs $0.005 per hour or about $3.60 per month, and does support zone resiliency. A similar email has been sent to users, with the same dates.

Although these extra charges will not make much of a ripple in enterprise accounts, they can be noticeable, for example if you are an individual developing an application and trying to keep within a strict budget.

book reviews, books, reviews, tech, Uncategorized

Reimagining Collaboration by Phil Simon

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This is a book about collaboration in the new era of Zoom, Teams, Slack and other such tools – not that they are completely new, but the pandemic and enforced remote working caused a huge boom in usage and some permanent changes in the way people work together. Author Phil Simon is a US specialist in business communications, and associated with the Agile methodology of software development – quite appropriate for this book, since collaboration is at the heart of Agile.

There are a few themes here. Simon believes that organisations need strong collaboration in order to thrive, and personally I think that is spot on. He spends some time distinguishing between collaboration and other related but different things like communication (a pre-requisite but insufficient on its own), or co-operation which can be a passive relationship; people can co-operate without actually collaborating.

Despite all the this, the main topic of the part 1 of this book, I am not sure that Simon ever nails what collaboration really is, at least not in this book. He has a go at it and there are many examples given of what it is not, but it remains, in my mind, a bit elusive. I did like his metric of organizational health: “The ability to rally around a common vision, execute effectively, and create a culture of innovation.”

Simon does show a good understanding of the human factor in productivity. He talks about managers versus makers, and how managers feel the need to communicate often with many people, while makers need to reduce distraction and focus on a task; I am not sure if he had software development in mind but this is a good description of what developers need.

Part 2 then gets to the heart of the book: better collaboration through technology. The key concept Simon uses is what he calls a “collaboration hub,” meaning any of a number of tools which form a central internet-connected space where users can interact with one another. This includes what the author calls the big three, Slack, Teams and Zoom, as well as other applications such as Expensify or Canva.  

The author is a user of Slack and of Google Docs and while he shows a commendable neutrality in the sense that he considers other tools such as Teams equally effective, adding that “It’s fair to call the similarities around today’s internal collaboration hubs remarkable,” his greater depth of knowledge of the tools he mainly uses does show. There is really much more about Slack than about Teams, and that is something to be aware of. Teams users can still benefit from the book but less so than Slack users.

There is a big theme here though which is that the author considers email, especially internal email, a blocker to collaboration. He gives reasons, including that inboxes tend to die when an individual leaves the company; that email is gaffe-prone since a careless email, or a careless reply-all, cannot be unsent; and that emailing attachments like spreadsheets leads to multiple forks of the same data. In fact, toward the end of the book Simon remarks that “Effective, long-term collaboration cannot take place via email. Period.” He also recommends ditching internal email completely.

While I have some sympathy with this view, I think it is overdone. I reminded myself that one of the most successful collaborative projects of all time, the Linux kernel, is based on email lists. 

Still, Simon is quite correct, a collaboration tool with channels for team members has lots of advantages over email, gathering all the communications in one spam-free place and making search much easier.

Part three of the book is called “moving from theory to practice” and contains lots of discussion about how organizations can move towards using collaboration hubs and what can go wrong. Then part four peeks into the future and envisages smarter collaboration hubs which use AI to book meetings for us, automatically transcribes meetings and sends automatic alerts to Slack channels.

There is plenty of wisdom though I could have done with more on practical questions about how to get the most from Slack or Teams. How many channels or Teams should you have? When should you have a video conference versus a message chat? Should we have our collaboration hubs always open or sign out sometimes? Who should be able to create a channel, or should anyone? And what more advanced or intricate features of the products are worthwhile?

I enjoyed Simon’s willingness to be blunt at times, as well as some amusing reflections like “In my consulting days, I often saw project managers call meetings essentially because they were bored.”

Towards the end of the book we also get this: “Just because the discussion or task takes place in a hub doesn’t mean that it’s truly collaborative.” I agree. What then is the magic that enables an organization to be collaborative? In the end it is corporate culture rather than tools that matter most. I think the author recognizes that, but after reading the book, I am still not clear about the best way to get to the collaborative culture to which we should aspire.

Thanks to Netgalley for an electronic review copy of this title

professional, software development, tech

Web page memory usage: how much is too much?

I have a web application that loads names into a picklist and the question came up: how many names would be too much for the web page to handle? What about 5,000 names, for example?

Modern web browsers have a memory snapshot built in. Just press F12 and there it is. So I fired up my application with over 5,000 names loaded into an array and displayed in a scrolling div. 2.5 MB.

Then I visited Facebook. Logged in, the page reported over 78 MB.

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Google’s clean-looking home page? Not logged in, 11.2 MB.

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Twitter? Logged in, 83 MB.

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This was enough for me to stop worrying about the memory impact of 5,000 names in my web application. With our casual acceptance of multi-MB web pages it is easy to forget that the complete works of Shakespeare in plain text is 5.5 MB and compresses to less than half of that.

Just because you can do something, does not mean you should. Smaller is better and faster, and software bloat of various kinds is responsible for many performance issues.

There are trade-offs though both in time and in performance. Maybe it is better to load just a few names, and retrieve more from the server when needed. It is easy to test such things. Nevertheless, I found it useful to get some perspective on the memory usage of modern web sites.

tech

Windows Subsystem for Linux 2 will not start: a possible fix

I find that Windows Subsystem for Linux (WSL) sometimes fails to start after rebooting Windows 11. Once it is up and running it is fine.

Symptoms are that WSL fails to open and the wsl command hangs. VS Code, if set to open in WSL, fails to open the folder.

Rather than rebooting, you can also try the steps here. It is a matter of finding the process id for LxssManager:

tasklist /svc /fi “imagename eq svchost.exe”

then using End Process Tree in the Task Manager Details view for that process ID to terminate it. It will then restart automatically or you can use the wsl command as usual.

apple, microsoft, professional, tech, Uncategorized, windows

Using an M1 Mac after a lifetime of mainly Windows

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So I got an M1 MacBook Pro back in April and it is time for a quick brain dump on my experience. I am not travelling as much as I did pre-lockdown, so although I got the Mac as a replacement for an ancient Windows laptop it gets used at home too. My usual desktop PC is a few years old but a decent spec gaming PC withCore i7-7700 3.6 GHz, 16GB RAM and Nvidia RTX 2060 GPU. I have been happy with it; but I do find myself thinking “why not just use the MacBook” when needing to fire up a computer, a subconscious preference that bears examination. Most of my work is writing, web browsing and coding.

I do not particularly prefer the macOS UI to that of Windows. It is more consistent because Apple managed iOS vs macOS sensibly whereas Microsoft made a hash of Windows desktop vs Windows CE vs Windows Phone vs Windows 8 and has now settled on a thing called WinUI but scratch the surface of Windows and you still find UI that has not changed for decades.

I digress though. I do not mind the Windows UI, I am used to it. What I do mind though is annoyances like the always-broken Windows search, and the way certain actions cause lengthy pauses that make me wonder what my PC is doing. In my case, sorting a large directory in Windows Explorer takes an age. Another little issue is that creating a new folder works fine, but renaming it causes a long pause. There also seem to be some focus issues. I create a new folder, I rename it and press Enter. Eventually it renames, but half the time the focus mysteriously switches to a different folder.

I realise that these problems do not occur with a new install of Windows and that I could pop out and buy a Surface laptop and it would be fine. For a bit. Windows, it seems to me, still suffers from the cruft problem beautifully described by Verity Stob 20 years ago. I do not think Macs are completely immune (I had a Mac Mini where I upgraded the OS once too often and it crawled) but does seem to me more resistant.

There is another thing that I like about the MacBook. You close the lid and it sleeps. You open the lid minutes, hours or days later, and it wakes. This has never worked well for me on Windows, though it is meant to do the same. I can believe that it is hard to implement, but when it works it is a huge benefit.

There is also the unwanted advertising that has crept into the Windows UI especially since Windows 11. Working on the MacBook I do notice its absence; I can better focus on what I want to do.

From a developer perspective, the performance of the M1 Pro is a delight. I work mostly in Visual Studio Code on both platforms; even on Windows I have come to prefer VS Code for most types of work. There is also the fact that Unix-like operating systems have won in server and web applications, so there is less friction there.

Launchpad: reminiscent of the Windows 8 Start screen?

Microsoft came up with a great application launcher in the Windows 95 Start menu – and improved it until it reached its peak in Windows 7. I also like the Windows 8 full-screen version. Windows 10 and 11 are not so good though. You get inadvertent web searches, as well as the problem of apps that you search for not appearing for strange reasons. The Mac Launchpad, which reminds me of the Windows 8 full-screen Start menu, seems to work well. You type what you want and all the matches appear.

What do I miss when not using Windows? It is mainly a matter of working out new ways to do certain tasks. I do miss Hyper-V and WSL (Windows Subsystem for Linux) though I have had success with UTM for running both Windows and Ubuntu on the Mac. The integration of WSL with the desktop OS is great though. Microsoft Office still works best on Windows though not to the extent of a few years back. There is no Paint or Notepad, and favourites like Notepad++ do not run natively, but Preview works for cropping images and alternatives to Windows utilities exist.

Sometimes you are pushed towards the command line which is not a bad thing. No WinSCP for example, so use scp instead, and do some helper scripts for common tasks. You end up saving time. (I realise you can script WinSCP as well). And no need for Putty; just type ssh or script the command line you need.

I do expect though to use Windows less in future, and for me that is a big change.

apple, book reviews, books, professional, tech

Book review: After Steve by Tripp Mickle

This is billed as a book about a company, but is more accurately described as about two people, Tim Cook and Jony Ive, respectively CEO and former Chief Design Officer at Apple, one of the world’s biggest and most profitable companies. The author Tripp Mickle is a reporter at the Wall Street Journal where he covered Apple for four years.

Mickle has a thesis: that under Cook Apple’s profitability has flourished but its design-led innovation has faltered, damaged in 2011 when co-founder Steve Jobs died at the age of 56. “It’s unclear if design will ever regain its position as the dominant voice over product direction,” he writes. In his epilogue, Mickle says that “Cook’s aloofness and unknowability made him an imperfect partner for an artist who wanted to bring empathy to every product.” The author mentions several times that Cook “seldom went to the design studio to see Ive’s team work.”

The book has amazing detail and represents the outcome of interviews with “more than two hundred current and former Apple employees” supplemented by further interviews with their family members, friends, suppliers of Apple, competitors, and government officials. There is lots of dialogue in the accounts of key incidents, drawn either from recordings or “reconstructed based on the recollections of people familiar with the events described.” As you read, you feel immersed in the company. It is a great achievement, particularly (as the author also notes) considering that “at Apple, current and former employees adhere to a strict code of silence.” There is a thick section of notes and references.

After Steve then is essential reading for Apple watchers. That said, I have a couple of reservations. At 512pp this is a lengthy work and for me, too long. It is occasionally repetitive, the writing is professional but at times pedestrian. Further, if your interest is in Apple the company rather than Cook and Ive, it is overly focused on those two people.

This last point is perhaps why Mickle misses the impact of Apple Silicon, the series of ARM-based processors which began with the A series and took over from Intel as the technology in Mac computers from November 2020 with the launch of the M1. Recently Apple has announced the M2 with claimed performance improvements of up to 18% for the CPU and 35% for the GPU, compared to the M1.

Apple Silicon matters because it dramatically improves over x86 in its power/performance ratio, making the company’s laptops and iPads a delight compared to their competition. It may not be design-based, and it builds on ARM and the work of others, but it is a huge advance and gives the company’s hardware an edge over its Windows and Android competition that is hard to counter. Johny Srouji, in charge of Apple Silicon? Not mentioned by Mickle.

I would have preferred the book to be shorter (though researchers may be glad of its detail). What of its central thesis? Mickle makes the point that Apple Watch has a disappointing lack of focus, which I agree with, and that projects like the Apple electric car appear to have faltered. The Beats acquisition had a mixed outcome, and this was a puzzle to me too. Apple did not need Beats, its culture was alien, and my sense is that Apple Music would have flourished equally well without it.

I do think though that since Jobs Apple has developed something with iPhone-level impact and that is Apple Silicon and the M series in particular. I also think that Mickle misses something of the big picture. Buying a smartphone or computer? There is the Android jungle, or the Windows jungle, or Apple. For many it is hardly a choice; and the fact that this is more than ever true more than a decade after the passing of Jobs is huge credit to those involved and makes the accusation “how Apple became a trillion-dollar company and lost its soul” ring just a bit hollow.

music, reviews

Abba 10 CD box set 2022

Does anyone still buy CDs? There are a few reasons: they sound great when well mastered, you can rip them and not be dependent on an internet connection to listen to them, they can have nice packaging and booklets, and if you are a little bit obsessive about sound quality you can play the exact version you want to play instead of whatever the streaming service decides to send you.

I love Abba, who could not? and since I don’t have many of their albums I bought the new 10 CD box. I am not quite sure what the proper name for the set is, on the box it just says Abba CD Album Box Set. It ties in with the current Abba avatar-based show.

image

A few observations. The music is great, Abba never made a bad album in my opinion. You get all the studio albums plus a Tracks CD of singles like Fernando and Gimme! Gimme! Gimme! a Man after Midnight. So far so good; and the set is reasonable value considering the number of albums. The latest, Voyage from November 2021, is included.

Now for a few gripes. Abba’s albums in general are not superlative in sound quality but some releases have been better than others. If you want the full dynamic range you have to seek out the earliest CD releases, and this box is no different. The sound is not crushed to death but it still falls short for no good reason other than needless pursuit of “loudness”. There is also a bit too much bass boost on some of the tracks, not least Gimme! Gimme! Gimme! where the percussion sounds a little distorted. It is fine on the early CD box Thank you for the Music.

Second, why is it that an Abba fan like this one can do a better job fixing problems in the source tapes, than the professionals can manage? These are little details like a click in Money Money Money at the 0.33 mark and a slight glitch in Dancing Queen at around 2.06-2.11.

Third, why is this set so short, omitting any bonus tracks other than the singles on Tracks, and that CD is just 38 minutes long? My hunch is that the label made the CDs short enough that they would also fit on the vinyl box, which is all rather topsy-turvy in my opinion.

Fourth, the CDs are packaged in simple card sleeves reproducing the LPs, which means tiny type on things like the rear of Arrival, and you don’t get the lyrics which were on the inner sleeves of the original albums.

Overall then I’m disappointed. Nevertheless, Thank you for the music.

software development, tech

Installing Ubuntu 22.04 on Apple M1 with UTM

I  started with Arch Linux for Linux development  on  M1, which works, but succumbed to Ubuntu just because it is so widely used and therefore easier to find help. It is also supported by VS Code for remote development, as I am aiming for something similar to a WSL setup on Windows and using VS Code on the host side. I had problems installing 22.04 though;  the install completed but trying to boot resulted in:

EFI stub: booting Linux Kernel

EFI stub: Using DTB from configuration table

EFI stub: Exiting boot services

and there it would stay.

The fix I found was to update QEMU:

sudo port selfupdate

sudo port install qemu

after which Ubuntu started without issue (no need to reinstall).

Following this I was able to install and use the Remote – SSH extension in VS Code which worked first time.

Small points to note:

  • I accepted the option in Ubuntu to install the OpenSSH server during installation
  • In UTM I changed the networking for the VM to Emulated VLAN rather than Shared Network, in order to use port forwarding. I forwarded both the SSH port 22 and also the HTTP port 80, to different ports on the Mac, so that I can test web applications running on Ubuntu.

Thanks also to Liz Rice for her post here.

tech, Uncategorized, xbox

Fixing an Xbox controller broken by Elden Ring

I have been enjoying Elden Ring on the Xbox but not so much when my controller broke. I recall the same thing happening with Dark Souls. Maybe it’s the way I play, but the problem is that the right bumper is used for a quick attack, which I use constantly. The bumpers seem to be less robust than the triggers, so after a while it breaks.

Fortunately the current Xbox controllers (I have a Carbon Black) are easy to fix. The hardest part is getting the textured panels off the controller handles; like so many modern electronics cases, these are a press fit and have to be levered off while trying not to break or scratch them. Then you undo two screws each side using a Torx T8 security screwdriver and another screw under the label in the battery compartment. Then you can carefully remove first a central rear panel and next the rear bumpers.

This revealed the problem: a small plastic tab had broken.

Gluing the tab back probably would not last long; but fortunately compatible bumper parts are available for a few pounds on eBay. I bought two (one for next time) and everything is fine.