HumanTalks October 2015

Note: For this post, I'll try to write in english. I'm now working in an english-speaking company and I'm already writing emails in english to give feedback on the HumanTalks sessions. I'm not used to write such lengthy posts in english, though. Hopefully I'll get better at it the more I do it.

This HumanTalks session took place at UrbanLinkers, a Parisian recruiting company. The room was packed and we had just enough seats for everybody.


IBM Bluemix

The first talk was by Alain Airbon, which was very nervous. He said so right at the beginning of his talk, but it was quite obvious. He talked about Bluemix, which is the PaaS developed by IBM. He showed us how the Bluemix dashboard UI was working, but it felt a lot like a commercial presentation, and we did not learn anything we could have learned in 10 minutes in the dashboard ourselves.

I did not really understood what Bluemix was actually doing. He spent very little time explaining what a PaaS was (he compared it to IaaS, explaining the differences, but even for IaaS, I would have loved to have an explanation). I think Amazon is to IaaS what Heroku is to PaaS, but I'm not even sure.

It was clear that Alain was very nervous, and wanted the audience to like his talk on stage, but it did feel too shallow, and too commercial. And developers have a very low tolerance to bullshit. An advice I could give to first-time speakers would be to talk about something they really like and are passionate about, so the audience can feel how they feel about it. A personal feedback on how he used Bluemix to deploy one of its own projects would have worked better I think.

Still, I liked the way he introduced Bluemix: "Bluemix is simply Cloudfoundry, repainted to the IBM colors. We might not be better than the alternatives, but at least we follow standards and use an open-source project". This was honest and straight to the point.

I hope this first talk will not discourage him from trying again another time, we're still open to hosting him again and can give some advice on public speaking.

How to fail at code review

The second talk was by Michel Domenjoud, from Octo Technology. He was giving the same talk two days after at the Agile Tour Lille. Michel shared with us some stories about code review, and specifically peer review.

Michel is convinced that regular code review inside a team will lead to better, more maintainable and more stable code in production. He announces numbers as high as a ROI of 4 to 1. For one hour spent on code review, we can save up to four hours of debugging. Almost 65% of bugs can be found before shipping, thanks to the reviews.

How to fail at code review

Michel then shared 3 personal stories with us. First, he told us about that time when he worked for 10 days on a feature that was originally estimated to 3 days. In the end he did a lot of refactoring, touched hundred of classes and thousands of LOC. Once done, he asked a colleague for a review. 30 minutes later, one of them came back to him with a few issues spotted, mostly variable naming and a few typos. So they pushed to production.

Two weeks later, a bug popped in. After two days investigating, it was obvious that the bug came from this new feature, so they had to start debugging live.

Here is what they did wrong. First, they rushed the whole thing. On average, you cannot review more than 300LOC/hour, so take your time and do it with a fresh mind, not late at night. If the feature involves a lot of changes, it's expected that the review also take some time. Also, Michel should not have waited 10 days before submitting his work for a review, he should have asked feedback earlier.

But also, it seems that the reviewer did not know what to look for in the code review. He found typos and naming issues, but he did not really looked inside the logic and the behavior. No-one told him what to look for.

In the second story, Michel told us about Bob who came to him one day at the coffee machine. Bob was upset, he was saying that Martin code was really ugly, that he was still doing hard-coded SQL queries. Bob said he spent the last hour fixing the issues of Martin.

That was a perfect recipe for failing at code review as well. Bob never spoke to Martin directly, he just complained to Michel. Instead they should have talked together. Then, Bob should never have corrected the issues himself. The author should fix its own errors, otherwise he will never learn. And finally this whole story of hard coded SQL queries had never been written anywhere, so you cannot blame people for not following it.

The last story was about Kent and Beckie (pun intended that were arguing loudly about snake_case vs camelCase, shouting in the open-space. In the end, Kent left saying "you're a shitty coder, Beckie!".

This is really the worse that could happen. Kent was criticizing people, not their code. When in doubt, always refer to the principles of the Egoless Programming. Your code is not an extension of yourself. It can be judged, improved or deleted, this has nothing to do with you.

Also, it was not the right time to argue about snake_case or camelCase. Refrain from starting a framework war or any kind of trolling when doing a code review. This is not the time nor the place. Find compromises, write it down and follow it.

I really liked this talk. Michel gave real-life examples that we can all understand. Coding involves much more human contact that we could initially imagine. The code of a project belongs to the community building it, not to the one person that wrote it. Anyone can write code. Writing maintainable, understandable, shareable code is harder. The only way to do it properly is to talk to your colleagues, and code together.

Memory techniques

This talk, I gave it myself. I've written a summary of it on my blog.

How to hack your electricity meter

C├ędric Finance told us about how he hacked its electricity meter at home with a Raspberry Pi. He did not actually really hacked it, he simply plugged the Raspberry Pi to the public part of the meter and read the data sent by it.

He did it because he realized that we never really know how much electricity we're using. When we leave the water tap open, it's obvious how much water we're wasting, and we can almost see money flowing down the sink. For electricity, we never really know until we receive our bill.

Getting back to the technical side of things. The meter sends data as a stream of keys/values. The data is not self explanatory but fortunately the spec is available and it can easily be parsed. He realized that it gave him a much more accurate set of information than what was printed on its bill.

As soon as he got the data, he pushed it to Thingspeak, a SaaS service to push streamed data and generate graphs. With that he quickly saw that its water heater was malfunctioning. It was supposed to only work on off-peak hours, but was actually always working. Knowing that, he fixed it.

He then dropped Thingspeak to build a custom dashboard to capture data with a higher frequency. He let it run for more than a year and was then able to compare usage from one year to the next.

At first he did it just for fun, but he soon realized that he could better understand its electricity consumption and make some improvements to it. Now he went ever further, with humidity and heat sensors in his home and graphs for all that.


Once again, a nice series of talks. And once again, my favorites are the personal sharing of experience.

Next month will be a special event as we'll be celebrating the HumanTalks Paris birthday, in a bigger room than usual. Hope to see you there.

Tags : #humantalks

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