This is basically terrifying. A catalog of race conditions and reliability horrors around the POSIX filesystem abstraction in Linux — it’s a wonder anything works. ‘Where’s this documented? Oh, in some mailing list post 6-8 years ago (which makes it 12-14 years from today). The fs devs whose posts I’ve read are quite polite compared to LKML’s reputation, and they generously spend a lot of time responding to basic questions, but it’s hard for outsiders to troll [sic] through a decade and a half of mailing list postings to figure out which ones are still valid and which ones have been obsoleted! I don’t mean to pick on filesystem devs. In their OSDI 2014 talk, the authors of the paper we’re discussing noted that when they reported bugs they’d found, developers would often respond “POSIX doesn’t let filesystems do that”, without being able to point to any specific POSIX documentation to support their statement. If you’ve followed Kyle Kingsbury’s Jepsen work, this may sound familiar, except devs respond with “filesystems don’t do that” instead of “networks don’t do that”.I think this is understandable, given how much misinformation is out there. Not being a filesystem dev myself, I’d be a bit surprised if I don’t have at least one bug in this post.’
Interesting performance-related tweak going into Lucene — based on the Bkd-Tree I think: https://users.cs.duke.edu/~pankaj/publications/papers/bkd-sstd.pdf . Being used for all numeric index types, not just multidimensional ones?
Cutting and pasting from Facebook for posterity… there are some really solid tips in here. ‘Some people plan their lives out and then there are people like me who randomly do things and suddenly, in retrospect, it looks like a grand plan has come together. In reality it’s more like my subconscious pulls in useful info and pokes me to go learn things as required. If you live/work in Ireland, the following “grand plan” might be useful. This year has apparently been “figure out how to retire” year. It started late last year with finally organising all my private Irish pensions (2 from employers, 1 personal). In the process I learned the following: * Many Irish pension plans allow you to start drawing down from them at age 50. There are downsides to this, but if you have several of them it allows you more room to avoid stock market downturns when you purchase annuities. * You can get 25% of each pension as a tax-free lump sum. I also learned a few property things. The key thing is that if you have a buy-to-let property you should *not* pay off its mortgage early. You can deduct 75% of the interest you pay against the taxes you’d owe for rental income. That means the interest you pay will essentially be close to or even under the rate of inflation. A residential mortgage might have a lower interest rate nominally, but the effective interest rate is higher. The Irish state pension is changing. If you are 68 after 2020 the rules have changed – and they’re now much simpler. Work for 10 years and you get the minimum state pension (1/3 of a full pension). Work for 20, you get 2/3 of of a state pension. Work for 30, you get a full pension. But you can’t collect it till you’re 68 and remember that Irish employers can apparently force you to “retire” at 65 (ageism is legal). So you need to bridge those 3 years (or hope they change the law to stop employers from doing that). When I “retired” I kept a part time job for a number of reasons, but one was because I suspected I needed more PRSI credits for a pension. And it turns out this was correct. Part-time work counts as long as you make more than €38/week. And self-employment counts as long as you make more than €5,000/year. You can also make voluntary PRSI contributions (around €500/year but very situation dependent). If you’ve worked in Europe or the US or Canada or a few other countries, you can get credits for social welfare payments in those countries. But if you have enough here and you have enough for some pension in the other country, you can draw a pension from both. Lastly most people I’ve talked to about retirement this year have used the analogy of legs on a stool. Every source of post-retirement income is a leg on the stool – the more legs, the more secure your retirement. There are lots of options for legs: * Rental income. This is a little wobbly as legs go at least for me. But if you have more than one rental property – and better yet some commercial rental property – this leg firms up a bit. Still, it’s a bit more work than most. * Savings. This isn’t very tax-efficient, but it can help fill in blank spots some legs have (like rental income or age restrictions) or maximise another legs value (weathering downturns for stock-based legs). And in retirement you can even build savings up. Sell a house, the private pension lump sum, etc. But remember you’re retired, go have fun. Savings won’t do you much good when you’re dead. * Stocks. I’ve cashed all mine in, but some friends have been more restrained in cashing in stocks they might have gotten from employers. This is a volatile leg, but it can pay off rather well if you know what you’re doing. But be honest with yourself. I know I absolutely don’t know what I’m doing on this so stayed away. * Government pension. This is generally a reliable source of income in retirement. It’s usually not a lot, but it does tend to last from retirement to death and it shows up every month. You apply once and then it just shows up each month. If you’ve worked in multiple countries, you can hedge some bets by taking a pension in each country you qualify from. You did pay into them after all. * Private pension. This can also give you a solid source of income but you need to pay into it. And paying in during your 20s and 30s really pays off later. But you need to make your investments less risky as you get into your late 50s – so make sure to start looking at them then. And you need to provide yourself some flexibility for starting to draw it down in order to survive market drops. The crash in 2007 didn’t fully recover until 2012 – that’s 5 years. * Your home. Pay off your mortgage and your home can be a leg. Not having to pay rent/mortgage is a large expense removed and makes the other legs more effective. You can also “sell down” or look into things like reverse mortgages, but the former can take time and has costs while the latter usually seems to have a lot of fine print you should read up on. * Part-time work. I know a number of people who took part-time jobs when they retired. If you can find something that doesn’t take a huge amount of time that you’d enjoy doing and that people will pay you for, fantastic! Do that. And it gets you out of the house and keeping active. For friends who are geeks and in my age cohort, I note that it will be 2037 around the time we hit 65. If you know why that matters, ka-ching!’ Another particularly useful page about the state pension: “Six things every woman needs to know about the State pension”, Irish Times, Dec 1 2015, https://www.irishtimes.com/business/personal-finance/six-things-every-woman-needs-to-know-about-the-state-pension-1.2448981 , which links to this page to get your state pension contribution record: http://www.welfare.ie/en/pages/secure/ RequestSIContributionRecord.aspx
As Glynn Moody noted, if UK police, intelligence agencies, HMRC and others call all legally hack phones and computers, that also means that digital evidence can be easily and invisibly planted. This will undermine future court cases in the UK, which seems like a significant own goal…
3 months ago when we, at nanit.com, came to evaluate which Docker orchestration framework to use, we gave ECS the first priority. We were already familiar with AWS services, and since we already had our whole infrastructure there, it was the default choice. After testing the service for a while we had the feeling it was not mature enough and missing some key features we needed (more on that later), so we went to test another orchestration framework: Kubernetes. We were glad to discover that Kubernetes is far more comprehensive and had almost all the features we required. For us, Kubernetes won ECS on ECS’s home court, which is AWS.
Links for 2015-12-14
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