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eschaton posted:bug me if you have any questions, I missed helping out in the Core Data labs at WWDC this year thanks i'll probably have tons of questions soon, i am struggling a bit with the key value observer system, i have a table view i want to update when there's a new object of a certain type in the object store, but i'm not really sure how to do that, i can watch objects just fine i think but this for some reason eludes me
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# ? Sep 25, 2014 09:03 |
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# ? May 16, 2024 17:30 |
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I'm sad rim is dying now I'll never get to go to a technology conference and see a keynote by a Canadian dual ceo, attend a presentation on using REST in android (lol), and get $1,000 in free electronics again course crapple is dying too so maybe next years WWDC lmbo
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# ? Sep 25, 2014 09:50 |
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tef posted:See also XSA-108 tef posted:It's not bash related, it's just a high impact vuln coming out soon: I don't have any details beyond a) it's happening, and b) good luck with AWS this weekend tef is this going to make my life a living hell next week? Blinkz0rz fucked around with this message at 12:19 on Sep 25, 2014 |
# ? Sep 25, 2014 11:58 |
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i need tips about good algorithm and linear algebra books for laymen, i have no background in maths and my book "Data structures and algorithms in C++" is a bit obtuse for me sometimes , are there any good books or sites i can read up on?
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# ? Sep 25, 2014 12:12 |
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Blinkz0rz posted:tef is this going to make my life a living hell next week? Part of that stuff is related to this: http://www.itnews.com.au/News/396180,amazon-forced-to-reboot-ec2-to-patch-xen-bug.aspx quote:Amazon Web Services has started urgently rebooting Elastic Compute Cloud (EC2) instances in all its regions, after an unknown bug was discovered in the open-source Xen virtualisation platform used by the company. The people who never expected netsplits, or were fine with single points of failures (and punted on quick-recovery options) will have a real great time starting around 2AM EST tomorrow (11PM PST tonight), up until early next week, as their infrastructure gradually gets shut down and restarted by force. Now I'm guessing that vuln will be pretty drat serious, so people who then operate their own Xen stuff but are not big enough to be part of the XSA-108 pre-release are gonna have an even better time starting Oct 1.
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# ? Sep 25, 2014 12:52 |
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ugh
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# ? Sep 25, 2014 13:18 |
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tbh that won't be terrible for us. it just means i have to finally patch those last few windows boxes that are affected by the plug and play cleanup bug
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# ? Sep 25, 2014 13:21 |
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MononcQc posted:The people who never expected netsplits, or were fine with single points of failures (and punted on quick-recovery options) will have a real great time starting around 2AM EST tomorrow (11PM PST tonight), up until early next week, as their infrastructure gradually gets shut down and restarted by force. remember when a major early Bitcoin exchange was run on an EC2 instance? and evaporated when the instance was rebooted because they never sprang for storage, taking all its customers' Bitcoins with it? good times
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# ? Sep 25, 2014 18:36 |
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master of the sea posted:thanks i'll probably have tons of questions soon, i am struggling a bit with the key value observer system, i have a table view i want to update when there's a new object of a certain type in the object store, but i'm not really sure how to do that, i can watch objects just fine i think but this for some reason eludes me do you want to know when some other process adds an instance of a particular entity to your store? or some other thread/queue in the same process? for the former, you'll have to do a periodic query, there's no way around it (unless you implement some sort of IPC yourself) for the latter, there's a notification you can observe that the managed object context will post when it saves, you can get the IDs of the affected objects from that and ask the IDs for the entities of the objects they represent to see if their object is an instance of the kind of entity you need to deal with
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# ? Sep 25, 2014 18:41 |
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master of the sea posted:i need tips about good algorithm and linear algebra books for laymen, i have no background in maths and my book "Data structures and algorithms in C++" is a bit obtuse for me sometimes , are there any good books or sites i can read up on?
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# ? Sep 25, 2014 18:42 |
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eschaton posted:do you want to know when some other process adds an instance of a particular entity to your store? or some other thread/queue in the same process? yeah i just figured out how to make my app do this with NSNotificationCenter, man this framework is really easy to work with, all i need is time to read the docs and it just slides into place, very cool. i am about to spend 99 of my earth dollars on enrollment in the ios dev program now, except when i click buy now i get redirected to the "updating apple store" page timb, fire everyone
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# ? Sep 25, 2014 22:47 |
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The Leck posted:not a book, but i found this coursera course pretty helpful in walking through some basic algorithm and data structure stuff that i definitely didn't get in school. https://www.coursera.org/course/algo thanks, gonna check it out
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# ? Sep 25, 2014 22:47 |
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I like gilbert strang's linear algebra book
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# ? Sep 25, 2014 23:01 |
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Symbolic Butt posted:I like gilbert strang's linear algebra book that was a pretty good book
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# ? Sep 25, 2014 23:02 |
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Axler's Linear Algebra Done Right takes a v geometric approach which a) helps a lot with intuition and b) generalises well to infinite dimensional spaces, which is something that ppl who learn LA in terms of matrices have trouble with
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# ? Sep 25, 2014 23:18 |
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linear algebra owns bones
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# ? Sep 25, 2014 23:21 |
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what's a good primer to make sure i have all the prereqs in place for linear algebra?
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# ? Sep 25, 2014 23:24 |
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master of the sea posted:what's a good primer to make sure i have all the prereqs in place for linear algebra? to learn linear algebra all you really need to know is regular algebra
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# ? Sep 25, 2014 23:27 |
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master of the sea posted:what's a good primer to make sure i have all the prereqs in place for linear algebra? basic algebra is all u need. add subtract divide multiply. that's all u need for "matrix algebra" if u want legit linear algebra u will want to study up on stuff like basic set theory (injectivity, surjectivity, functions, set membership, set builder notation, set operations), basic proofs (induction, contradictions etc) "linear algebra done right" is more the latter, some of strang's stuff is more the former, u get more of the former w/ golub and van loan but if u wanna understand why matrix algorithms work u need to understand linear algebra fairly deeply
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# ? Sep 25, 2014 23:28 |
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master of the sea posted:what's a good primer to make sure i have all the prereqs in place for linear algebra? I've written a bunch of words about it before that I can't find via my phone, but it's structure is uniquely suited to self study and it covers everything from number lines through to multivariable calculus e: it's also way more than you need just for LA, but if you're having trouble with intro to LA then there's probably other parts of yr maths ed that need shoring up too
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# ? Sep 25, 2014 23:30 |
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coffeetable posted:Stroud's Engineering Mathematics yeah i remembered that book cover from earlier in the thread! thanks man, gonna put it on my list, i really need to touch up math, i haven't been doing any for a long long time
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# ? Sep 25, 2014 23:45 |
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Malcolm XML posted:basic algebra is all u need. add subtract divide multiply. that's all u need for "matrix algebra" axler is an elementary text, it has no prerequisites. don't waste any time reviewing baby algebra, it will only hinder you because you'll be using algebra rules that either don't apply to arbitrary finite dimensional vector space, or that you haven't proved yet. everything you need to know is in there. golub and van loan is a great book also but is not an algebra book
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# ? Sep 26, 2014 00:40 |
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i used this book in college and I liked it. theoretical text tho, not really good for engineering imo Linear Algebra (Friedberg et al)
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# ? Sep 26, 2014 00:57 |
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i still have that one. good books called "topic"
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# ? Sep 26, 2014 01:38 |
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MononcQc posted:Part of that stuff is related to this: http://www.itnews.com.au/News/396180,amazon-forced-to-reboot-ec2-to-patch-xen-bug.aspx why would amazon not just move the guests to a different host before rebooting the host?
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# ? Sep 26, 2014 01:59 |
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Shaggar posted:why would amazon not just move the guests to a different host before rebooting the host?
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# ? Sep 26, 2014 03:25 |
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im seriously asking
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# ? Sep 26, 2014 03:26 |
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because reboots are far easier and much less likely to fail, most of the HA stuff is handled at the application level than treating the os as black box option a) copy state across, magically reforward network connections in flight to new machine, hope you don't mind some mild downtime as you do this or option b) copy state across, run checkpointing at disk/netowork level, firing in the same network and disk i/o across two machines, lagging it out to gently caress as you hope both of them keep in sync or option c) if you wanted HA on amazon why are you running things on one instance
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# ? Sep 26, 2014 03:29 |
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essentially, if you stop and copy across *magically*, you will lose in flight connections, and it's much easier to just reboot after patching the host machine, than to do this, and will take longer than a reboot of the instances. the other option of running an instance in parallel and checkpointing everything that goes in and out of the instance as a black box will introduce a heck of latency as you wait for confirmation on everything before switching over, and requires a lot of network consensus to do so really it's because rebooting is quicker, simpler, works, and doing robustness at the application layer is simpler, easier, and works.
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# ? Sep 26, 2014 03:31 |
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works fine in VMware and VMware sucks.
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# ? Sep 26, 2014 03:32 |
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or if you like, you don't pay amazon enough to care
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# ? Sep 26, 2014 03:32 |
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a cloud based service where you need to be concerned w/ the host is a not very good cloud based service
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# ? Sep 26, 2014 03:34 |
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Shaggar posted:a service where you need to be concerned is a not very good service
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# ? Sep 26, 2014 03:40 |
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Shaggar posted:works fine in VMware and VMware sucks. heh so, you're telling me, you can switch over to a new host, by pausing the process, snapshoting cpu state + ram, and copy this lump across all memory across the network, all with less latency than rebooting, meanwhile storing all transient connections upstream while this happens, then restarting the process and replaying all incoming traffic. in a faster time than rebooting? or, that amazon will use twice as much instance capacity to checkpoint all instances, slowing them to a crawl to keep them in sync while this happens. yep, sounds realistic. Shaggar posted:a cloud based service where you need to be concerned w/ the host is a not very good cloud based service i'd personally rather deal with a reboot than unknown amounts of latency and crap performance. i can do HA already by having multiple instances. which you should be doing anyway, because, hey, databases fall over, machines crash, software fails, latency happens, and there isn't a magic wand to do the right thing because *the application atop the instance* determines the best thing to do. here's a nickle kid, go write yourself a better distributed system.
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# ? Sep 26, 2014 03:43 |
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i want a computer in which i need never be concerned if it crashes regardless of what i run atop of it.
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# ? Sep 26, 2014 03:44 |
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tef posted:heh it worked fine in VMware five years ago. have a spare host machine that doesn't have anyone on it. transition one host's vms to it. reboot the host. transition the next host's vms to that one, etc the only reason to do it this way is that they probably can't do it that way fast enough before the vuln goes public. obvi it isn't as fast to do it the seamless way but then again you don't have to kill everyone's instances.
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# ? Sep 26, 2014 09:25 |
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you should have app level HA for anything you care about tho, it's true.
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# ? Sep 26, 2014 09:25 |
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ShimaTetsuo posted:axler is an elementary text, it has no prerequisites. don't waste any time reviewing baby algebra, it will only hinder you because you'll be using algebra rules that either don't apply to arbitrary finite dimensional vector space, or that you haven't proved yet. everything you need to know is in there. no u rly need to review babby algebra because the majority of errors people do is basic stuff related to that. lots of linear algebra is related to baby algebra anyway so make sure u know that numerical linear algebra is usually what programmers consider linear algebra so g&vl is probs gonna come up
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# ? Sep 26, 2014 09:49 |
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azure handles this via upgrade domains and i think amazon has Availability Zones so lol @ you if you dont deal with this correctly
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# ? Sep 26, 2014 09:51 |
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# ? May 16, 2024 17:30 |
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Malcolm XML posted:azure handles this via upgrade domains and i think amazon has Availability Zones so lol @ you if you dont deal with this correctly like azure will email u in advance saying "yo if u dont have 2 upgrade domains u r a moron hth"
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# ? Sep 26, 2014 09:52 |