terrible programmers: my god, it's full of chars

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > YOSPOS > terrible programmers: my god, it's full of chars

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master of the sea: Apr 16, 2003; *skweeeeeee*

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

# ? Sep 25, 2014 09:03

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# ? May 16, 2024 06:33

Luigi Thirty: Apr 30, 2006; Emergency confection port.

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

# ? Sep 25, 2014 09:50

Blinkz0rz: May 27, 2001; MY CONTEMPT FOR MY OWN EMPLOYEES IS ONLY MATCHED BY MY LOVE FOR TOM BRADY'S SWEATY MAGA BALLS

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

master of the sea: Apr 16, 2003; *skweeeeeee*

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?

# ? Sep 25, 2014 12:12

MononcQc: May 29, 2007

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.

[...]

However, an AWS customer who declined to be named said the reboot was not simply maintenance and was instead due to an unspecified bug in the Xen platform, XSA-108, which will not be revealed until October 1 United States time.

[...]

Rightscale engineer Thorsten von Eicken said the reboots would take place over the next few days, starting September 27 Australian time and ending on October 1.

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.

# ? Sep 25, 2014 12:52

Blinkz0rz: May 27, 2001; MY CONTEMPT FOR MY OWN EMPLOYEES IS ONLY MATCHED BY MY LOVE FOR TOM BRADY'S SWEATY MAGA BALLS

ugh

# ? Sep 25, 2014 13:18

Blinkz0rz: May 27, 2001; MY CONTEMPT FOR MY OWN EMPLOYEES IS ONLY MATCHED BY MY LOVE FOR TOM BRADY'S SWEATY MAGA BALLS

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

# ? Sep 25, 2014 13:21

eschaton: Mar 7, 2007; Don't you just hate when you wind up in a store with people who are in a socioeconomic class that is pretty obviously about two levels lower than your own?

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

# ? Sep 25, 2014 18:36

eschaton: Mar 7, 2007; Don't you just hate when you wind up in a store with people who are in a socioeconomic class that is pretty obviously about two levels lower than your own?

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

# ? Sep 25, 2014 18:41

The Leck: Feb 27, 2001

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?

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

# ? Sep 25, 2014 18:42

master of the sea: Apr 16, 2003; *skweeeeeee*

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?

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

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

# ? Sep 25, 2014 22:47

master of the sea: Apr 16, 2003; *skweeeeeee*

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

# ? Sep 25, 2014 22:47

Symbolic Butt: Mar 22, 2009; (_!_); Buglord

I like gilbert strang's linear algebra book

# ? Sep 25, 2014 23:01

rotor: Jun 11, 2001; classic case of pineapple derangement syndrome

Symbolic Butt posted:

I like gilbert strang's linear algebra book

that was a pretty good book

# ? Sep 25, 2014 23:02

coffeetable: Feb 5, 2006; TELL ME AGAIN HOW GREAT BRITAIN WOULD BE IF IT WAS RULED BY THE MERCILESS JACKBOOT OF PRINCE CHARLES

YES I DO TALK TO PLANTS ACTUALLY

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

# ? Sep 25, 2014 23:18

Bloody: Mar 3, 2013

linear algebra owns bones

# ? Sep 25, 2014 23:21

master of the sea: Apr 16, 2003; *skweeeeeee*

what's a good primer to make sure i have all the prereqs in place for linear algebra?

# ? Sep 25, 2014 23:24

rotor: Jun 11, 2001; classic case of pineapple derangement syndrome

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

# ? Sep 25, 2014 23:27

Malcolm XML: Aug 8, 2009; I always knew it would end like ｔｈｉｓ．

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

# ? Sep 25, 2014 23:28

coffeetable: Feb 5, 2006; TELL ME AGAIN HOW GREAT BRITAIN WOULD BE IF IT WAS RULED BY THE MERCILESS JACKBOOT OF PRINCE CHARLES

YES I DO TALK TO PLANTS ACTUALLY

master of the sea posted:

what's a good primer to make sure i have all the prereqs in place for linear algebra?

Stroud's Engineering Mathematics

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

# ? Sep 25, 2014 23:30

master of the sea: Apr 16, 2003; *skweeeeeee*

coffeetable posted:

Stroud's Engineering Mathematics

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

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

# ? Sep 25, 2014 23:45

ShimaTetsuo: Sep 9, 2001; Maximus Quietus

Malcolm XML posted:

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

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

# ? Sep 26, 2014 00:40

compuserved: Mar 20, 2006; Nap Ghost

i used this book in college and I liked it. theoretical text tho, not really good for engineering imo

Linear Algebra (Friedberg et al)

# ? Sep 26, 2014 00:57

Brain Candy: May 18, 2006

i still have that one. good books called "topic" :allears:

# ? Sep 26, 2014 01:38

Shaggar: Apr 26, 2006

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

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.

why would amazon not just move the guests to a different host before rebooting the host?

# ? Sep 26, 2014 01:59

tef: May 30, 2004; -> some l-system crap ->

Shaggar posted:

why would amazon not just move the guests to a different host before rebooting the host?

# ? Sep 26, 2014 03:25

Shaggar: Apr 26, 2006

im seriously asking

# ? Sep 26, 2014 03:26

tef: May 30, 2004; -> some l-system crap ->

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 :v:

# ? Sep 26, 2014 03:29

tef: May 30, 2004; -> some l-system crap ->

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.

# ? Sep 26, 2014 03:31

Shaggar: Apr 26, 2006

works fine in VMware and VMware sucks.

# ? Sep 26, 2014 03:32

tef: May 30, 2004; -> some l-system crap ->

or if you like, you don't pay amazon enough to care

# ? Sep 26, 2014 03:32

Shaggar: Apr 26, 2006

a cloud based service where you need to be concerned w/ the host is a not very good cloud based service

# ? Sep 26, 2014 03:34

JewKiller 3000: Nov 28, 2006; by Lowtax

Shaggar posted:

a service where you need to be concerned is a not very good service

# ? Sep 26, 2014 03:40

tef: May 30, 2004; -> some l-system crap ->

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. :yayclod:

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.

# ? Sep 26, 2014 03:43

tef: May 30, 2004; -> some l-system crap ->

i want a computer in which i need never be concerned if it crashes regardless of what i run atop of it.

# ? Sep 26, 2014 03:44

Dessert Rose: May 17, 2004; awoken in control of a lucid deep dream...

tef posted:

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.

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.

# ? Sep 26, 2014 09:25

Dessert Rose: May 17, 2004; awoken in control of a lucid deep dream...

you should have app level HA for anything you care about tho, it's true.

# ? Sep 26, 2014 09:25

Malcolm XML: Aug 8, 2009; I always knew it would end like ｔｈｉｓ．

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.

golub and van loan is a great book also but is not an algebra book

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

# ? Sep 26, 2014 09:49

Malcolm XML: Aug 8, 2009; I always knew it would end like ｔｈｉｓ．

azure handles this via upgrade domains and i think amazon has Availability Zones so lol @ you if you dont deal with this correctly

# ? Sep 26, 2014 09:51

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# ? May 16, 2024 06:33

Malcolm XML: Aug 8, 2009; I always knew it would end like ｔｈｉｓ．

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"

# ? Sep 26, 2014 09:52

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