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  • Linux - real-world hardware RAID controller tuning (scsi and cciss)

    - by ewwhite
    Most of the Linux systems I manage feature hardware RAID controllers (mostly HP Smart Array). They're all running RHEL or CentOS. I'm looking for real-world tunables to help optimize performance for setups that incorporate hardware RAID controllers with SAS disks (Smart Array, Perc, LSI, etc.) and battery-backed or flash-backed cache. Assume RAID 1+0 and multiple spindles (4+ disks). I spend a considerable amount of time tuning Linux network settings for low-latency and financial trading applications. But many of those options are well-documented (changing send/receive buffers, modifying TCP window settings, etc.). What are engineers doing on the storage side? Historically, I've made changes to the I/O scheduling elevator, recently opting for the deadline and noop schedulers to improve performance within my applications. As RHEL versions have progressed, I've also noticed that the compiled-in defaults for SCSI and CCISS block devices have changed as well. This has had an impact on the recommended storage subsystem settings over time. However, it's been awhile since I've seen any clear recommendations. And I know that the OS defaults aren't optimal. For example, it seems that the default read-ahead buffer of 128kb is extremely small for a deployment on server-class hardware. The following articles explore the performance impact of changing read-ahead cache and nr_requests values on the block queues. http://zackreed.me/articles/54-hp-smart-array-p410-controller-tuning http://www.overclock.net/t/515068/tuning-a-hp-smart-array-p400-with-linux-why-tuning-really-matters http://yoshinorimatsunobu.blogspot.com/2009/04/linux-io-scheduler-queue-size-and.html For example, these are suggested changes for an HP Smart Array RAID controller: echo "noop" > /sys/block/cciss\!c0d0/queue/scheduler blockdev --setra 65536 /dev/cciss/c0d0 echo 512 > /sys/block/cciss\!c0d0/queue/nr_requests echo 2048 > /sys/block/cciss\!c0d0/queue/read_ahead_kb What else can be reliably tuned to improve storage performance? I'm specifically looking for sysctl and sysfs options in production scenarios.

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  • Please help to find a solution for two way, real-time synchronization on Centos 5.5 64Bit

    - by Vipul Limbachiya
    I am in need of a real time, two way synchronization software for Centos 5.5 / 64Bit. Here's little explanation: It needs to be able to perform: Two way synchronization. It must be realtime. By realtime means it can be almost realtime, i.e. a delay of 1 second for example is fine. And the folders are on the same server. I am currently using GlusterFS across two webservers. However, it has extremely poor small file read performance and it's slowing down my website. There's nothing more that can be done to improve this, I have already tested many configurations. As a solution, I was going to mount a RAM drive (tmpfs) that mirrors the GlusterFS web files but get the webserver to use the RAM drive. The issue is that I need two way realtime mirroring or replication between glusterfs and the RAM drive. I need this is as Apache writes files as wells. As I said, realtime two way synchronization across two folders. Which are in fact 2 different mounts points. The RAM (tmpfs) mount poing and the GlusterFS mount point. I already know about: Rsync - Which is one way Unison - Which is not realtime Please suggest me any solution free or paid. Thanks in advance

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  • Apache load balancer with https real servers and client certificates

    - by Jack Scheible
    Our network requirements state that ALL network traffic must be encrypted. The network configuration looks like this: ------------ /-- https --> | server 1 | / ------------ |------------| |---------------|/ ------------ | Client | --- https --> | Load Balancer | ---- https --> | server 2 | |------------| |---------------|\ ------------ \ ------------ \-- https --> | server 3 | ------------ And it has to pass client certificates. I've got a config that can do load balancing with in-the-clear real servers: <VirtualHost *:8666> DocumentRoot "/usr/local/apache/ssl_html" ServerName vmbigip1 ServerAdmin [email protected] DirectoryIndex index.html <Proxy *> Order deny,allow Allow from all </Proxy> SSLEngine on SSLProxyEngine On SSLCertificateFile /usr/local/apache/conf/server.crt SSLCertificateKeyFile /usr/local/apache/conf/server.key <Proxy balancer://mycluster> BalancerMember http://1.2.3.1:80 BalancerMember http://1.2.3.2:80 # technically we aren't blocking anyone, but could here Order Deny,Allow Deny from none Allow from all # Load Balancer Settings # A simple Round Robin load balancer. ProxySet lbmethod=byrequests </Proxy> # balancer-manager # This tool is built into the mod_proxy_balancer module allows you # to do simple mods to the balanced group via a gui web interface. <Location /balancer-manager> SetHandler balancer-manager Order deny,allow Allow from all </Location> ProxyRequests Off ProxyPreserveHost On # Point of Balance # Allows you to explicitly name the location in the site to be # balanced, here we will balance "/" or everything in the site. ProxyPass /balancer-manager ! ProxyPass / balancer://mycluster/ stickysession=JSESSIONID </VirtualHost> What I need is for the servers in my load balancer to be BalancerMember https://1.2.3.1:443 BalancerMember https://1.2.3.2:443 But that does not work. I get SSL negotiation errors. Even when I do get that to work, I will need to pass client certificates. Any help would be appreciated.

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  • How can we improve overall Programmer Education & Training?

    - by crosenblum
    Last week, I was just viewing this amazing interview by Kevin Rose of Phillip Rosedale, of Second Life. And they had an amazing discussion about how to find, hire and identify good programmer's, and how hard it is to find good ones. Which has lead me to really think about the way we programmer's learn, are taught. For a majority of us, myself included, we are self-taught. Which is great about being a programmer, anyone can learn and develop skills. But this also means, that there is no real standards of what a good programmer is/are, and what kind of environment's encourage the growth of programming skills. This isn't so much a question, but just a desire in me, to see how we can change the culture of programming, and the manager's of programming, so that education and self-improvement is encouraged. There are a lot of avenue's for continued education, youtube videos, books, conferences, but because of the experiental nature of what we do, it isn't always clear what's important to learn and to master. Let's look at the The Joel 12 Steps. The Joel Test Do you use source control? Can you make a build in one step? Do you make daily builds? Do you have a bug database? Do you fix bugs before writing new code? Do you have an up-to-date schedule? Do you have a spec? Do programmers have quiet working conditions? Do you use the best tools money can buy? Do you have testers? Do new candidates write code during their interview? Do you do hallway usability testing? I think all of these have important value, but because of something I call the Experiential Gap, if a programmer or manager has never experienced any of the negative consequences for not having done items on the list, they will never see the need to do any of them. The Experiental Gap, is my basic theory, that each of us has different jobs and different experiences. So for some of us, that have always worked with dozens of programmer's, source control is a must have. But for people who have always been the only programmer, they can not imagine the need for source control. And it's because of this major flaw in how we learn, that we evaluate people by what best practices they do or not do, and the reason for either can start a flame war. We always evaluate people in our field by what they do, and think "Oh if this guy/gal isn't doing xyz best practice, he/she can't be a good programmer, so let's not waste time or energy talking to them." This is exactly why we have so many programming flame wars, that it becomes, because of the Experiental Gap, we can't imagine people not having made the decisions that we have had to made. So this has lead me to think, that we totally need to rethink how we train, educate and manage programmer's. For example, what percentage of you have had encouragement by your manager's to go to conferences, and even have them pay for it? For me, and a lot of people, this is extremely rare, a lot of us would love to go to conferences, to learn more, but the money ain't there to do that. So the point of this question is really to spark a lot of how can we train, learn and manage better? How can we create a new culture of learning that doesn't insult people for not having the same job experiences. Yes we all have jobs and work to do, but our ability to do our jobs well, depends on our desire, interest and support in improving our mastery of our skills. Right now, I see our culture being rather disorganized, we support the elite, but those tons of us that want to get better, just don't have enough support to learn and improve ourselves. I mean, do we as an industry, want to be perceived as just replaceable cogs? Thank you...

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  • Collision between sprites in game programming?

    - by Lyn Maxino
    I've since just started coding for an android game using eclipse. I've read Beginning Android Game Programming and various other e-books. Recently, I've encountered a problem with collision between sprites. I've used this code template for my program. package com.project.CAI_test; import java.util.Random; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Rect; public class Sprite { // direction = 0 up, 1 left, 2 down, 3 right, // animation = 3 back, 1 left, 0 front, 2 right int[] DIRECTION_TO_ANIMATION_MAP = { 3, 1, 0, 2 }; private static final int BMP_ROWS = 4; private static final int BMP_COLUMNS = 3; private static final int MAX_SPEED = 5; private GameView gameView; private Bitmap bmp; private int x = 0; private int y = 0; private int xSpeed; private int ySpeed; private int currentFrame = 0; private int width; private int height; public Sprite(GameView gameView, Bitmap bmp) { this.width = bmp.getWidth() / BMP_COLUMNS; this.height = bmp.getHeight() / BMP_ROWS; this.gameView = gameView; this.bmp = bmp; Random rnd = new Random(); x = rnd.nextInt(gameView.getWidth() - width); y = rnd.nextInt(gameView.getHeight() - height); xSpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; ySpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; } private void update() { if (x >= gameView.getWidth() - width - xSpeed || x + xSpeed <= 0) { xSpeed = -xSpeed; } x = x + xSpeed; if (y >= gameView.getHeight() - height - ySpeed || y + ySpeed <= 0) { ySpeed = -ySpeed; } y = y + ySpeed; currentFrame = ++currentFrame % BMP_COLUMNS; } public void onDraw(Canvas canvas) { update(); int srcX = currentFrame * width; int srcY = getAnimationRow() * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bmp, src, dst, null); } private int getAnimationRow() { double dirDouble = (Math.atan2(xSpeed, ySpeed) / (Math.PI / 2) + 2); int direction = (int) Math.round(dirDouble) % BMP_ROWS; return DIRECTION_TO_ANIMATION_MAP[direction]; } public boolean isCollition(float x2, float y2) { return x2 > x && x2 < x + width && y2 > y && y2 < y + height; } } The above code only detects collision between the generated sprites and the surface border. What I want to achieve is a collision detection that is controlled by the update function without having to change much of the coding. Probably several lines placed in the update() function. Tnx for any comment/suggestion.

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  • Reading graph inputs for a programming puzzle and then solving it

    - by Vrashabh
    I just took a programming competition question and I absolutely bombed it. I had trouble right at the beginning itself from reading the input set. The question was basically a variant of this puzzle http://codercharts.com/puzzle/evacuation-plan but also had an hour component in the first line(say 3 hours after start of evacuation). It reads like this This puzzle is a tribute to all the people who suffered from the earthquake in Japan. The goal of this puzzle is, given a network of road and locations, to determine the maximum number of people that can be evacuated. The people must be evacuated from evacuation points to rescue points. The list of road and the number of people they can carry per hour is provided. Input Specifications Your program must accept one and only one command line argument: the input file. The input file is formatted as follows: the first line contains 4 integers n r s t n is the number of locations (each location is given by a number from 0 to n-1) r is the number of roads s is the number of locations to be evacuated from (evacuation points) t is the number of locations where people must be evacuated to (rescue points) the second line contains s integers giving the locations of the evacuation points the third line contains t integers giving the locations of the rescue points the r following lines contain to the road definitions. Each road is defined by 3 integers l1 l2 width where l1 and l2 are the locations connected by the road (roads are one-way) and width is the number of people per hour that can fit on the road Now look at the sample input set 5 5 1 2 3 0 3 4 0 1 10 0 2 5 1 2 4 1 3 5 2 4 10 The 3 in the first line is the additional component and is defined as the number of hours since the resuce has started which is 3 in this case. Now my solution was to use Dijisktras algorithm to find the shortest path between each of the rescue and evac nodes. Now my problem started with how to read the input set. I read the first line in python and stored the values in variables. But then I did not know how to store the values of the distance between the nodes and what DS to use and how to input it to say a standard implementation of dijikstras algorithm. So my question is two fold 1.) How do I take the input of such problems? - I have faced this problem in quite a few competitions recently and I hope I can get a simple code snippet or an explanation in java or python to read the data input set in such a way that I can input it as a graph to graph algorithms like dijikstra and floyd/warshall. Also a solution to the above problem would also help. 2.) How to solve this puzzle? My algorithm was: Find shortest path between evac points (in the above example it is 14 from 0 to 3) Multiply it by number of hours to get maximal number of saves Also the answer given for the variant for the input set was 24 which I dont understand. Can someone explain that also. UPDATE: I get how the answer is 14 in the given problem link - it seems to be just the shortest path between node 0 and 3. But with the 3 hour component how is the answer 24 UPDATE I get how it is 24 - its a complete graph traversal at every hour and this is how I solve it Hour 1 Node 0 to Node 1 - 10 people Node 0 to Node 2- 5 people TotalRescueCount=0 Node 1=10 Node 2= 5 Hour 2 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5(Rescued) Node 0 to Node 1 = 10 Node 0 to Node 2 = 5 Node 1 to Node 2 = 4 TotalRescueCount = 10 Node 1 = 10 Node 2= 5+4 = 9 Hour 3 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5+4 = 9(Rescued) TotalRescueCount = 9+5+10 = 24 It hard enough for this case , for multiple evac and rescue points how in the world would I write a pgm for this ?

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  • Bidirectional real-time sync of large file tree between two distant linux servers

    - by dlo
    By large file tree I mean about 200k files, and growing all the time. A relatively small number of files are being changed in any given hour though. By bidirectional I mean that changes may occur on either server and need to be pushed to the other, so rsync doesn't seem appropriate. By distant I mean that the servers are both in data centers, but geographically remote from each other. Currently there are only 2 servers, but that may expand over time. By real-time, it's ok for there to be a little latency between syncing, but running a cron every 1-2 minutes doesn't seem right, since a very small fraction of files may change in any given hour, let alone minute. EDIT: This is running on VPS's so I might be limited on the kinds of kernel-level stuff I can do. Also, the VPS's are not resource-rich, so I'd shy away from solutions that require lots of ram (like Gluster?). What's the best / most "accepted" approach to get this done? This seems like it would be a common need, but I haven't been able to find a generally accepted approach yet, which was surprising. (I'm seeking the safety of the masses. :) I've come across lsyncd to trigger a sync at the filesystem change level. That seems clever though not super common, and I'm a bit confused by the various lsyncd approaches. There's just using lsyncd with rsync, but it seems this could be fragile for bidirectionality since rsync doesn't have a notion of memory (eg- to know whether a deleted file on A should be deleted on B or whether it's a new file on B that should be copied to A). lipsync appears to be just a lsyncd+rsync implementation, right? Then there's using lsyncd with csync2, like this: http://www.axivo.com/community/threads/lightning-fast-synchronization-with-csync2-and-lsyncd.121/ ... I'm leaning towards this approach, but csync2 is a little quirky, though I did do a successful test of it. I'm mostly concerned that I haven't been able to find a lot of community confirmation of this method. People on here seem to like Unison a lot, but it seems that it is no longer under active development and it's not clear that it has an automatic trigger like lsyncd. I've seen Gluster mentioned, but maybe overkill for what I need? UPDATE: fyi- I ended up going with the original solution I mentioned: lsyncd+csync2. It seems to work quite well, and I like the architectural approach of having the servers be very loosely joined, so that each server can operate indefinitely on its own regardless of the link quality between them.

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  • Use cellular emulator with a REAL WinMo device?

    - by Ranhiru
    I don't whether this is even possible which is obviously why I am asking this question :) Is it in any way possible to leverage functionality the Cellular Emulator on a REAL PHYSICAL device?? :) So when I test it on my device, I really do not have to send real SMS(s) to test my MessageInteceptor. On a sidenote, why does MessageInteceptor fails after several messages to intercept messages?? :( Thanx a lot in advance :)

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  • How did you get your first programming job?

    - by Gaz
    Hi All, I have some commercial programming experience although it was not my primary role (C# and Java), SCJP 6 cert, some SQL experience and have been doing a lot of Android programming (I have one app with 36,000 downloads). I have a degree in Chemistry and a Diploma in Programming (half a degree made up of 2nd/3rd year uni courses). I'm trying to get my first entry level programmer job but am finding it tough out there.......How did other people get there first jobs in programming?

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  • How to process audio in real time?

    - by user1756648
    I am giving some audio input through microphone. I recorded it in Audacity, it looks something like as shown below. I want to process this audio in real time. I mainly want to do this. 1) see real time audio amplitude vs time graph 2) perform some actions based on some thing (like if a specific type of hike is seen in audio, then do something, else do something else) Is there any python module or C library that can allow me to do this ?

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  • Why is sys+user > real in "time command"?

    - by shadyabhi
    I have a program that uses pthread library to do the matrix multiplication of 500x500 matrix. Each thread calculates 50 rows of the matrix. When I run tiem command:- shadyabhi@shadyabhi-desktop:~$ time ./a.out real 0m0.383s user 0m0.810s sys 0m0.000s shadyabhi@shadyabhi-desktop:~$ How come sys+user is greater than real time?

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  • Problem getting real IP in php

    - by leda
    I am using this to get real IP but i take empty from $_SERVER['HTTP_CLIENT_IP'],i take not empty only from $_SERVER['REMOTE_ADDR'].But i dont need the IP of proxy,i need the real ip of computers using some intranet.Can i get it?when $_SERVER['HTTP_CLIENT_IP'] does not return empty? function getRealIpAddr() { if (!empty($_SERVER['HTTP_CLIENT_IP'])) //check ip from share internet { $ip=$_SERVER['HTTP_CLIENT_IP']; } elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) //to check ip is pass from proxy { $ip=$_SERVER['HTTP_X_FORWARDED_FOR']; } else { $ip=$_SERVER['REMOTE_ADDR']; } return $ip; }

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  • NSMutableURLRequest returns null on real device, while returning image on simulator

    - by Yanchi
    I was testing my app that I've been working on for past 2 months. Basically it requests for JSON, that contains info about items. One field of JSON file is image_url. When I want to display this image, I need to download it from another server, that needs additional credentials. So it goes like this- In my cellForRowAtIndexPath I'm doing NSDictionary *aucdict = [jsonAukResults objectAtIndex:indexPath.row]; NSURL *imageURL = [NSURL URLWithString:[aucdict objectForKey:@"img_url"]]; NSString *authPString = [[[NSString stringWithFormat:@"login:password"]dataUsingEncoding:NSUTF8StringEncoding] base64EncodedString]; NSString *verifPString = [NSString stringWithFormat:@"Image %@",authPString]; NSMutableURLRequest *Prequest = [[NSMutableURLRequest alloc] initWithURL:imageURL]; [Prequest setValue:verifPString forHTTPHeaderField:@"Authorization"]; NSError *error = nil; NSURLResponse *resp = nil; NSData *picresult = [NSURLConnection sendSynchronousRequest:Prequest returningResponse:&resp error:&error]; UIImage *imageLoad = [[UIImage alloc] initWithData:picresult]; Now, I just obscured credentials (they are not login:password :)). My problem is, that right now, I get 3 items. All 3 have image on same server. I can get two of them with this code no problem. However third one is problematic, I always get (NULL) imageLoad. On my simulator, everything works fine, I get all 3 pictures. On real device I get error. I tried to NSURLConnection with error and response so I could debug better. This is what I got in my error. Printing description of error: Error Domain=NSURLErrorDomain Code=-1202 "The certificate for this server is invalid. You might be connecting to a server that is pretending to be “server name” which could put your confidential information at risk." UserInfo=0x1e5a3080 {NSErrorFailingURLStringKey=pictureLink.jpg, NSLocalizedRecoverySuggestion=Would you like to connect to the server anyway?, NSErrorFailingURLKey=pictureLink.jpg, NSLocalizedDescription=The certificate for this server is invalid. You might be connecting to a server that is pretending to be “server name” which could put your confidential information at risk., NSUnderlyingError=0x1e5a30e0 "The certificate for this server is invalid. You might be connecting to a server that is pretending to be “server name” which could put your confidential information at risk.", NSURLErrorFailingURLPeerTrustErrorKey=} I dont use SSL so Im really confused as what could cause this error. Btw, everything worked fine until now (this is my initial screen, so it's been done for good month and a half). Now I started to do graphics and this problem popped up :(

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  • Uploading files to a server that has Real Time Antivirus scan running

    - by zecougar
    I need to allow users to upload files onto a server that has an antivirus program running with real-time scanning switched on. What would be a good design to ensure that infected files are not uploaded to the server. Questions - would large files be copied onto disk and then immediately scanned, or would they be scanned as they are copied and not allowed to appear on disk if infected Should i build a seperate infrastructure around this to specifically ionvoke a scan on the copied file ? this might be an issue if the file is deleted through the real-time scan

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  • Real World Examples of read-write in concurrent software

    - by Richard Fabian
    I'm looking for real world examples of needing read and write access to the same value in concurrent systems. In my opinion, many semaphores or locks are present because there's no known alternative (to the implementer,) but do you know of any patterns where mutexes seem to be a requirement? In a way I'm asking for candidates for the standard set of HARD problems for concurrent software in the real world.

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  • An Alphabet of Eponymous Aphorisms, Programming Paradigms, Software Sayings, Annoying Alliteration

    - by Brian Schroer
    Malcolm Anderson blogged about “Einstein’s Razor” yesterday, which reminded me of my favorite software development “law”, the name of which I can never remember. It took much Wikipedia-ing to find it (Hofstadter’s Law – see below), but along the way I compiled the following list: Amara’s Law: We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run. Brook’s Law: Adding manpower to a late software project makes it later. Clarke’s Third Law: Any sufficiently advanced technology is indistinguishable from magic. Law of Demeter: Each unit should only talk to its friends; don't talk to strangers. Einstein’s Razor: “Make things as simple as possible, but not simpler” is the popular paraphrase, but what he actually said was “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience”, an overly complicated quote which is an obvious violation of Einstein’s Razor. (You can tell by looking at a picture of Einstein that the dude was hardly an expert on razors or other grooming apparati.) Finagle's Law of Dynamic Negatives: Anything that can go wrong, will—at the worst possible moment. - O'Toole's Corollary: The perversity of the Universe tends towards a maximum. Greenspun's Tenth Rule: Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp. (Morris’s Corollary: “…including Common Lisp”) Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law. Issawi’s Omelet Analogy: One cannot make an omelet without breaking eggs - but it is amazing how many eggs one can break without making a decent omelet. Jackson’s Rules of Optimization: Rule 1: Don't do it. Rule 2 (for experts only): Don't do it yet. Kaner’s Caveat: A program which perfectly meets a lousy specification is a lousy program. Liskov Substitution Principle (paraphrased): Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it Mason’s Maxim: Since human beings themselves are not fully debugged yet, there will be bugs in your code no matter what you do. Nils-Peter Nelson’s Nil I/O Rule: The fastest I/O is no I/O.    Occam's Razor: The simplest explanation is usually the correct one. Parkinson’s Law: Work expands so as to fill the time available for its completion. Quentin Tarantino’s Pie Principle: “…you want to go home have a drink and go and eat pie and talk about it.” (OK, he was talking about movies, not software, but I couldn’t find a “Q” quote about software. And wouldn’t it be cool to write a program so great that the users want to eat pie and talk about it?) Raymond’s Rule: Computer science education cannot make anybody an expert programmer any more than studying brushes and pigment can make somebody an expert painter.  Sowa's Law of Standards: Whenever a major organization develops a new system as an official standard for X, the primary result is the widespread adoption of some simpler system as a de facto standard for X. Turing’s Tenet: We shall do a much better programming job, provided we approach the task with a full appreciation of its tremendous difficulty, provided that we respect the intrinsic limitations of the human mind and approach the task as very humble programmers.  Udi Dahan’s Race Condition Rule: If you think you have a race condition, you don’t understand the domain well enough. These rules didn’t exist in the age of paper, there is no reason for them to exist in the age of computers. When you have race conditions, go back to the business and find out actual rules. Van Vleck’s Kvetching: We know about as much about software quality problems as they knew about the Black Plague in the 1600s. We've seen the victims' agonies and helped burn the corpses. We don't know what causes it; we don't really know if there is only one disease. We just suffer -- and keep pouring our sewage into our water supply. Wheeler’s Law: All problems in computer science can be solved by another level of indirection... Except for the problem of too many layers of indirection. Wheeler also said “Compatibility means deliberately repeating other people's mistakes.”. The Wrong Road Rule of Mr. X (anonymous): No matter how far down the wrong road you've gone, turn back. Yourdon’s Rule of Two Feet: If you think your management doesn't know what it's doing or that your organisation turns out low-quality software crap that embarrasses you, then leave. Zawinski's Law of Software Envelopment: Every program attempts to expand until it can read mail. Zawinski is also responsible for “Some people, when confronted with a problem, think 'I know, I'll use regular expressions.' Now they have two problems.” He once commented about X Windows widget toolkits: “Using these toolkits is like trying to make a bookshelf out of mashed potatoes.”

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  • When does "proper" programming no longer matter?

    - by Kai Qing
    I've been a full time programmer for about 8 years now. Web based mostly, ranging in weird jobs for clients. Never anything I "want" to do. So my experience is limited to what I've been contracted to do, having no real incentive to master anything in particular. So here's my scenario and ultimately what I wonder about... I've been building an android game in my spare time. It's using the libgdx library so quite a bit of the heavy lifting is done for me. I don't read much of the docs cause unless it's in tutorial format I will just not care, and ultimately most of my questions have already been asked on stackoverflow. I get along fine and my game works as expected... Suspiciously well, even. So much so that I wonder why one should bother to be "proper" when coding if the end result is ultimately the same. To be more specific, I used a hashtable because I wanted something close to an associative array. Human readable key values. In other places to achieve similar things, I use a vector. I know libgdx has vector2 and vector3 classes, but I've never used them. When I come across weird problems and search stackoverflow for help, I see a lot of people just reaming the questions that use a certain datatype when another one is technically "proper." Like using an ArrayList because it does not require defined bounds versus re-defining an int[] with new known boundaries. Or even something trivial like this: for(int i = 0; i < items.length; i ++) { // do something } I know it evaluates item.length on every iteration. I just don't care. I know items will never be more than 15 to 20 items. So why bother caring if I evaluate items.length on every iteration? So I wonder - why does everyone get all up in arms over this? Who cares if I use a less efficient datatype to get the job done? I ran some tests to see how the app performs using the lazy, get it done fast and don't look back method I just described versus the proper, follow the tutorial and use the exact data types suggested by the community. The results: Same thing. Average 45 fps. I opened every app on the phone and galaxy tab. Same deal. No difference. My game is pretty graphic intensive. It's not like it's just a simple thing. I expected it to perform kind of badly since I don't care to optimize image assets or... well, you probably get the idea. I'm making the game for fun. As a joke, really. But in doing so I'm working outside the normal scope of my job, which is to always follow the rules and do it the right way. So to say, I am without bounds here and this has caused me to wonder why I ever really care to be "proper" So I guess my question to you is this: Is there a threshold when it no longer matters to be proper? Is there a lasting, longer term consequence to the lazy, get it done and don't look back route? Is it ok to say - "so long as it gets the job done, I don't care?" Disclaimer: When I program my game, I am almost always drunk. I do it to remember why I got into this stuff to begin with because the monotony of client based web work will make you hate being a programmer. I'm having a blast and my game is not crashing, tests well, performs well, looks good on all devices so far and has no noticeable negative impact on any of my testing devices. I expected failure because I was being so drunkenly careless with my code, but to my surprise, it had no noticeable impact. I am now starting to question the need to be careful. Help me regain the ability to care! ... or explain why it's not a bad thing to not care. Secondary disclaimer: I am aware of the benefits of maintainability. For myself and others. Agreed. But it's not like someone happening across my inefficient int[] loop won't know what it does. As an experienced programmer those kinds of things are just clear on sight. I document the complex stuff for myself knowing I was drunk and will probably need a reminder. Those notes would clarify any confusion for someone who might ever gaze upon my ridiculous game - though the reality is that either I maintain it myself or it fades into time. I'm ok with that. But if it doesn't slow the device down, or crash, then crossing the t's and dotting the i's might actually require more time than it's worth.

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  • Quadratic Programming with Oracle R Enterprise

    - by Jeff Taylor-Oracle
         I wanted to use quadprog with ORE on a server running Oracle Solaris 11.2 on a Oracle SPARC T-4 server For background, see: Oracle SPARC T4-2 http://docs.oracle.com/cd/E23075_01/ Oracle Solaris 11.2 http://www.oracle.com/technetwork/server-storage/solaris11/overview/index.html quadprog: Functions to solve Quadratic Programming Problems http://cran.r-project.org/web/packages/quadprog/index.html Oracle R Enterprise 1.4 ("ORE") 1.4 http://www.oracle.com/technetwork/database/options/advanced-analytics/r-enterprise/ore-downloads-1502823.html Problem: path to Solaris Studio doesn't match my installation: $ ORE CMD INSTALL quadprog_1.5-5.tar.gz * installing to library \u2018/u01/app/oracle/product/12.1.0/dbhome_1/R/library\u2019 * installing *source* package \u2018quadprog\u2019 ... ** package \u2018quadprog\u2019 successfully unpacked and MD5 sums checked ** libs /opt/SunProd/studio12u3/solarisstudio12.3/bin/f95 -m64   -PIC  -g  -c aind.f -o aind.o bash: /opt/SunProd/studio12u3/solarisstudio12.3/bin/f95: No such file or directory *** Error code 1 make: Fatal error: Command failed for target `aind.o' ERROR: compilation failed for package \u2018quadprog\u2019 * removing \u2018/u01/app/oracle/product/12.1.0/dbhome_1/R/library/quadprog\u2019 $ ls -l /opt/solarisstudio12.3/bin/f95 lrwxrwxrwx   1 root     root          15 Aug 19 17:36 /opt/solarisstudio12.3/bin/f95 -> ../prod/bin/f90 Solution: a symbolic link: $ sudo mkdir -p /opt/SunProd/studio12u3 $ sudo ln -s /opt/solarisstudio12.3 /opt/SunProd/studio12u3/ Now, it is all good: $ ORE CMD INSTALL quadprog_1.5-5.tar.gz * installing to library \u2018/u01/app/oracle/product/12.1.0/dbhome_1/R/library\u2019 * installing *source* package \u2018quadprog\u2019 ... ** package \u2018quadprog\u2019 successfully unpacked and MD5 sums checked ** libs /opt/SunProd/studio12u3/solarisstudio12.3/bin/f95 -m64   -PIC  -g  -c aind.f -o aind.o /opt/SunProd/studio12u3/solarisstudio12.3/bin/ cc -xc99 -m64 -I/usr/lib/64/R/include -DNDEBUG -KPIC  -xlibmieee  -c init.c -o init.o /opt/SunProd/studio12u3/solarisstudio12.3/bin/f95 -m64  -PIC -g  -c -o solve.QP.compact.o solve.QP.compact.f /opt/SunProd/studio12u3/solarisstudio12.3/bin/f95 -m64  -PIC -g  -c -o solve.QP.o solve.QP.f /opt/SunProd/studio12u3/solarisstudio12.3/bin/f95 -m64   -PIC  -g  -c util.f -o util.o /opt/SunProd/studio12u3/solarisstudio12.3/bin/ cc -xc99 -m64 -G -o quadprog.so aind.o init.o solve.QP.compact.o solve.QP.o util.o -xlic_lib=sunperf -lsunmath -lifai -lsunimath -lfai -lfai2 -lfsumai -lfprodai -lfminlai -lfmaxlai -lfminvai -lfmaxvai -lfui -lfsu -lsunmath -lmtsk -lm -lifai -lsunimath -lfai -lfai2 -lfsumai -lfprodai -lfminlai -lfmaxlai -lfminvai -lfmaxvai -lfui -lfsu -lsunmath -lmtsk -lm -L/usr/lib/64/R/lib -lR installing to /u01/app/oracle/product/12.1.0/dbhome_1/R/library/quadprog/libs ** R ** preparing package for lazy loading ** help *** installing help indices   converting help for package \u2018quadprog\u2019     finding HTML links ... done     solve.QP                                html      solve.QP.compact                        html  ** building package indices ** testing if installed package can be loaded * DONE (quadprog) ====== Here is an example from http://cran.r-project.org/web/packages/quadprog/quadprog.pdf > require(quadprog) > Dmat <- matrix(0,3,3) > diag(Dmat) <- 1 > dvec <- c(0,5,0) > Amat <- matrix(c(-4,-3,0,2,1,0,0,-2,1),3,3) > bvec <- c(-8,2,0) > solve.QP(Dmat,dvec,Amat,bvec=bvec) $solution [1] 0.4761905 1.0476190 2.0952381 $value [1] -2.380952 $unconstrained.solution [1] 0 5 0 $iterations [1] 3 0 $Lagrangian [1] 0.0000000 0.2380952 2.0952381 $iact [1] 3 2 Here, the standard example is modified to work with Oracle R Enterprise require(ORE) ore.connect("my-name", "my-sid", "my-host", "my-pass", 1521) ore.doEval(   function () {     require(quadprog)   } ) ore.doEval(   function () {     Dmat <- matrix(0,3,3)     diag(Dmat) <- 1     dvec <- c(0,5,0)     Amat <- matrix(c(-4,-3,0,2,1,0,0,-2,1),3,3)     bvec <- c(-8,2,0)    solve.QP(Dmat,dvec,Amat,bvec=bvec)   } ) $solution [1] 0.4761905 1.0476190 2.0952381 $value [1] -2.380952 $unconstrained.solution [1] 0 5 0 $iterations [1] 3 0 $Lagrangian [1] 0.0000000 0.2380952 2.0952381 $iact [1] 3 2 Now I can combine the quadprog compute algorithms with the Oracle R Enterprise Database engine functionality: Scale to large datasets Access to tables, views, and external tables in the database, as well as those accessible through database links Use SQL query parallel execution Use in-database statistical and data mining functionality

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  • Scala programming language for beginners, is it a legend?

    - by ali
    Hi every one, I am Ali from Saudi Arabia. undoubtedly, Scala is one of the best programming language for any programmer to learn, but there is "good" problems that is faced especially by beginners, and what seems frustrating that these problems won't solve soon, so as a beginner and on behalf of beginners let me raise these "objective" questions: 1- why scala has no effective and stable development platform, in fact, it suffers many problems with Eclipse, Netbeat, and Intellij. 2- although I have looked for a clear,easy, and understandable explanation of how to get started with Scala, but fortunately, there was no article or guide that deserves to spend the time I have spent to read it. nobody could tell you clear steps that fit you as a beginner who wants to start his"HELLO WORLD" with Scala, while all other languages have its "HELLO WORLD" guides and books. thank you for your time, be sure that you read notes below. 1- I have no experience in programming language before. 2- don't tell me "not to begin with scala", simply, because I will do. 3- OS is windows vista home premium. 4- I hate excuses, such as Scala is new language......etc

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  • Programming texts and reference material for my Kindle DX, creating the ultimate reference device?

    - by mwilliams
    (Revisiting this topic with the release of the Kindle DX) Having owned both generation Kindle readers and now getting a Kindle DX; I'm very excited for true PDF handling on an e-ink device! An image of _Why's book on my Kindle (from my iPhone). This gives me a device capable of storing hundreds of thousands of pages that are full text search capable in the form factor of a magazine. What references (preferably PDF to preserve things such as code samples) would you recommend? Ultimately I would like reference material for every modern and applicable programming language (C, C++, Objective-C, Python, Ruby, Java, .NET (C#, Visual Basic, ASP.NET), Erlang, SQL references) as well as general programming texts and frameworks (algorithms, design patterns, theory, Rails, Django, Cocoa, ORMs, etc) and anything else that could be thought of. With so many developers here using such a wide array of languages, as a professional in your particular field, what books or references would you recommend to me for my Kindle? Creative Commons material a plus (translate that to free) as well as the material being in the PDF file format. File size is not an issue. If this turns out to be a success, I will update with a follow-up with a compiled list generated from all of the answers. Thanks for the assistance and contributing! UPDATE I have been using the Kindle DX a lot now for technical books. Check out this blog post I did for high resolution photos of different material: http://www.matthewdavidwilliams.com/2009/06/12/technical-document-pdfs-on-the-kindle-dx/

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  • Parallel programming, are we not learning from history again?

    - by mezmo
    I started programming because I was a hardware guy that got bored, I thought the problems being solved in the software side of things were much more interesting than those in hardware. At that time, most of the electrical buses I dealt with were serial, some moving data as fast as 1.5 megabit!! ;) Over the years these evolved into parallel buses in order to speed communication up, after all, transferring 8/16/32/64, whatever bits at a time incredibly speeds up the transfer. Well, our ability to create and detect state changes got faster and faster, to the point where we could push data so fast that interference between parallel traces or cable wires made cleaning the signal too expensive to continue, and we still got reasonable performance from serial interfaces, heck some graphics interfaces are even happening over USB for a while now. I think I'm seeing a like trend in software now, our processors were getting faster and faster, so we got good at building "serial" software. Now we've hit a speed bump in raw processor speed, so we're adding cores, or "traces" to the mix, and spending a lot of time and effort on learning how to properly use those. But I'm also seeing what I feel are advances in things like optical switching and even quantum computing that could take us far more quickly that I was expecting back to the point where "serial programming" again makes the most sense. What are your thoughts?

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  • How to learn a new programming language? And how to choose the appropriate language?

    - by Sebi
    Unfortunately my last question was closed, so I reformulated the question: I know this question was here a lot of times and can't be answered at all, but im not looking for a single name, but rather for an advice in my situation. I learned programming with Java and now I'm developing in Java for more or less 5 years (at the university) and I thinks my programming skills their are really ok/average. I have also small experience in C/C++ and C#. Now I have some spare time and I'd like to learn a new language or deepen the knowledge of Java/C/C++. But how to choose the right language to learn? I'd like to learn a language which will be usefull in the future concerning working in a software development business? I know there is no single answer, but I'm sure you could mention some languages that are more usefull than others. And what's the best way to learn such a language efficiently (bearing in mind that one has already learned some other languages)? Just doing tutorials? Or trying to implement a project? Trying to move a Java project to the new language?

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  • Life Cycle Tools Suite

    - by pearcewg
    I am looking to replace the life cycle tools currently used by my development teams. Tools that I'm looking for: Version Control Defect/Issue Tracking Requirements Tracking Test Case Management (potentially) Project Management: Project Status, hours entry I have a new beefy server (Windows 2008 Server) to run all tools on. I'm looking at COTS and Open Source options, but haven't decided so far. Other factors: Distributed team (different physical sites) Some Windows Development, some Linux Development Software, Firmware, Technical Writing need to be able to use it Recommendations on a good suite that will work together? If Open Source, best approach to run on the Windows 2008 Server?

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