jacques_chester

9 ms·

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by jacques_chester 3y ago
Bent Flyvbjerg calls (2) the "sublime". He points out that disastrous megaprojects get authorized because folks with the money and authority simply ignore the haters. https://en.wikipedia.org/wiki/Bent_Flyvbje
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by jacques_chester 3y ago
Not at Chainguard but I've watched their growth. I think this comes down to audience. To a lot of engineers it's just like ... "OK, that's nice. What else?" But for security teams in large enterprises, Chainguard is
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by jacques_chester 3y ago
Chainguard is proof that modern CI/CD is still a luxury product for most of the industry. They have a fantastic amount of automation behind image production, including some tools they rolled themselves (like apko). Disclosure: I am fri
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by jacques_chester 3y ago
The example of performance is interesting because as you say, there are often multiple jostling distributions under the surface (GC is one, but another doozy is CPU frequency scaling). One possible way out is to look for measurements that c
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by jacques_chester 3y ago
I have enjoyed a different experience of software development: the team breaks down stories into units of roughly equal complexity. Bugs get fixed first and do not contribute to velocity. Over a medium time frame I've seen this approac
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by jacques_chester 3y ago
Time between events is an approach Montgomery (8th EMEA) discusses in 7.3.5. The application there is for dealing with very low error/defect rates. I am not familiar with Wheeler's approach.
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by jacques_chester 3y ago
Oh, I hadn't noticed that emphasis. I guess I'm still stuck with the logarithm trick. I also just checked Montgomery and he reports that another simple transform is y^0.25 -- ie, square root of square root. I haven't tried it
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by jacques_chester 3y ago
Could you elaborate? I would love to learn more.
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by jacques_chester 3y ago
> If there is a fix-small-bugs month for example, or a fix-this-client's-bugs push, or a fix-the-bugs-in-the-new-feature campaign. The statistical properties of all these are not identical. For sure -- but these are surely specia
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by jacques_chester 3y ago
This is one of my favorite introductions to this topic area, especially since it gets away from the dominance of manufacturing applications for SPC.
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by jacques_chester 3y ago
> Software development is not a stable process. This causes confusion in my experience. "Stable" doesn't mean what it does in casual usage. It means that you have a mean and variance that are not varying over time (and t
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by jacques_chester 3y ago
The book I have my eye on is Nonparametric Statistical Process Control [1] by Chakraborti and Graham. In the past I've also tried the trick of taking the logarithm of values to convert a power distribution into a more normal-ish dist
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by jacques_chester 3y ago
This looks really good! I'll give it a read and perhaps add it to the reading list in the repo.
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by jacques_chester 3y ago
> Just a quick question though if I may - why/when would I want a n>1 group to average instead of treating them all independently as in XmR? Two reasons come to mind. First, for whatever reason, it might not be economical to me
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by jacques_chester 3y ago
Yes, in XmR the mR is the moving range -- ie the range between consecutive individual measurements, not the range of a single sample of multiple measurements. I can't think of a reference for the different charts off the top of my head
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by jacques_chester 3y ago
I think the SPC tests for detecting process shift would be EWMA and Cusum. The code has EWMA support, but it relies on a function to work and so is tied directly to PostgreSQL.
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by jacques_chester 3y ago
The XmR is in some ways the best beginner's plot because it's so immediately tied to the data. The other Shewhart charts work with samples , which is enough indirection to cause some mild confusion on first encounter (for me at l
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by jacques_chester 3y ago
I might add that if you're wondering about how the SPC tools work, read the comments in the SQL. I deliberately set out to write comments that would be helpful both to experienced SPC folks and to curious beginners. Unfortunately the
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by jacques_chester 3y ago
Oh hey, this is me. The background is that I've thought about applying SPC to software behavior for a long time[0]. While I was at Shopify I began to think about using it for detecting regressions in the YJIT benchmark suite[1]. My fir
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by jacques_chester 3y ago
For those wondering why an interview with Maxime is interesting: Maxime coinvented the Basic Block Versioning approach to JITs[0] during her studies. It's the basis for YJIT, which has landed big speedups for the C Ruby implementation
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by jacques_chester 3y ago
Thank you for the clarification. I am glad you disclosed and disappointed your friends didn't.
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by jacques_chester 3y ago
That someone has the skills for a job is distinct from whether they are able to uphold a simple moral principle like "don't cheat".
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by jacques_chester 3y ago
ChatGPT gushes apologies if you contradict its answers, that would probably be a reliable tell for now.
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by jacques_chester 3y ago
I agree that this is the likely long term outcome. But for now folks want to think that everyone needs to have memorized every individual screw, nail, nut and bolt in the edifice of computer science.
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by jacques_chester 3y ago
So, assuming they didn't know and approve, you cheated.
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by jacques_chester 3y ago
> I also am in favor of "open book" interviews. I recall reading an interviewing.io blog post[0] in which the dominant considerations interviewers weighed were (my interpretation): (1) Did they solve the problem optimally? (2
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by jacques_chester 3y ago
I cross-reference with the Leetcode editorial and some staring hard at code.
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by jacques_chester 3y ago
I've been grinding Leetcode lately and I've discovered that AI can oftentimes give a better explanation of a solution than Leetcode does. I can also followup questions without scanning through forum posts in hope someone was as co
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by jacques_chester 3y ago
Even neater. DuckDB has an implicit "SELECT *" if you just give it "FROM tablename", which fits your example.
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by jacques_chester 3y ago
> This is valid SQL. > SELECT 1; Something like Oracle's "dual" table would handle this corner case. Or just selecting a value from itself: FROM 1 SELECT 1; or FROM ::integer SELECT 1; Or whatha

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