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• SEO: many stackoverflow users' pages have got no Google PR and they are not indexed, why?

  - by Marco Demaio

  If you go to my user page on Stack Overflow and you check it with the Gogle bar you can see has got no PR at all (this does happen for almost any user page, even people with much higher reputation, the only exceptions seem to be the users in page 1, and some other users they have PR). My user page's Page Rank is not only zero, but not calculated at all. When PR is 0 or less than 1, but calculated the Google bar shows white, but when the PR is not even calculated like in my user page the Google bar shows in grey. I further more discovered that my user page is NOT EVEN INDEXED on Google, simple test is searching on Google for the exact page url: "http://stackoverflow.com/users/260080/marco-demaio" and you will see no result. The question is how can this be??? This is really weird to me because of the following reason: If you search on Google for "Marco Demaio" on stackoverflow site only (you can do this by searching "site:stackoverflow.com Marco Demaio") the search result shows hundreds of 'asking/answering questions' pages where I was 'tagged'!!! Let's check one of these: the 1st one that appears now (shows one of the question I asked). We can be sure this page is indexed in Google because comes out in a search moreover its PR is calculated, it's probably nearly zero, but still some PR flows there, the PR bar is not grey, but white: The page shown above has got links to my own user page. I checked the source code of the page shown above and the links are not hidden or set with a rel="nofollow", moreover I can't see any meta character excluding the links on the page from being followed. So what's happening? Why Google does not see my user page at all. Did stackoverflow do something to achieve this? If yes what did they do? Any explantion really appreciates (as always). P.S. obviously I checked also the code of my user page, but I could not find meta tags excluding Google search for the page. P.S. 2 in a desperate adventure I also checked StackOverflow robots but it does not seem to exclude user pages. UPDATE 1 following up on some answers, I did some more research. Excluding for a while the PR problem (since PR is not science), and looking only at the user page on StackOverflow NOT BEING INDEXED problem: pages do not seem to be indexed by Google because of the user reputation, this user for instance has got NOW 200 points less reputation than me and his page is indexed (while mine not). It does not seem even to be connected with months you have been on Stackoverflow, this user (almost my same reputation) has been there for 3 months only and his page is indexed (while mine not and I have been a user for 7 months). It's bizzarre! UPDATE February/2011 As of today the page got indexed by Google at least when you search for "site:stackoverflow.com Marco Demaio" it's the 1st page. The amazing thing is that it has still got NO PageRank at all: Google toolbar states loud and clear "No PageRank information available". It's odd!

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• Why your Netapp is so slow...

  - by Darius Zanganeh

  Have you ever wondered why your Netapp FAS box is slow and doesn't perform well at large block workloads?  In this blog entry I will give you a little bit of information that will probably help you understand why it’s so slow, why you shouldn't use it for applications that read and write in large blocks like 64k, 128k, 256k ++ etc..  Of course since I work for Oracle at this time, I will show you why the ZS3 storage boxes are excellent choices for these types of workloads. Netapp’s Fundamental Problem The fundamental problem you have running these workloads on Netapp is the backend block size of their WAFL file system.  Every application block on a Netapp FAS ends up in a 4k chunk on a disk. Reference:  Netapp TR-3001 Whitepaper Netapp has proven this lacking large block performance fact in at least two different ways. They have NEVER posted an SPC-2 Benchmark yet they have posted SPC-1 and SPECSFS, both recently. In 2011 they purchased Engenio to try and fill this GAP in their portfolio. Block Size Matters So why does block size matter anyways?  Many applications use large block chunks of data especially in the Big Data movement.  Some examples are SAS Business Analytics, Microsoft SQL, Hadoop HDFS is even 64MB! Now let me boil this down for you.  If an application such MS SQL is writing data in a 64k chunk then before Netapp actually writes it on disk it will have to split it into 16 different 4k writes and 16 different disk IOPS.  When the application later goes to read that 64k chunk the Netapp will have to again do 16 different disk IOPS.  In comparison the ZS3 Storage Appliance can write in variable block sizes ranging from 512b to 1MB.  So if you put the same MSSQL database on a ZS3 you can set the specific LUNs for this database to 64k and then when you do an application read/write it requires only a single disk IO.  That is 16x faster!  But, back to the problem with your Netapp, you will VERY quickly run out of disk IO and hit a wall.  Now all arrays will have some fancy pre fetch algorithm and some nice cache and maybe even flash based cache such as a PAM card in your Netapp but with large block workloads you will usually blow through the cache and still need significant disk IO.  Also because these datasets are usually very large and usually not dedupable they are usually not good candidates for an all flash system.  You can do some simple math in excel and very quickly you will see why it matters.  Here are a couple of READ examples using SAS and MSSQL.  Assume these are the READ IOPS the application needs even after all the fancy cache and algorithms.   Here is an example with 128k blocks.  Notice the numbers of drives on the Netapp! Here is an example with 64k blocks You can easily see that the Oracle ZS3 can do dramatically more work with dramatically less drives.  This doesn't even take into account that the ONTAP system will likely run out of CPU way before you get to these drive numbers so you be buying many more controllers.  So with all that said, lets look at the ZS3 and why you should consider it for any workload your running on Netapp today.  ZS3 World Record Price/Performance in the SPC-2 benchmark ZS3-2 is #1 in Price Performance $12.08ZS3-2 is #3 in Overall Performance 16,212 MBPS Note: The number one overall spot in the world is held by an AFA 33,477 MBPS but at a Price Performance of $29.79.  A customer could purchase 2 x ZS3-2 systems in the benchmark with relatively the same performance and walk away with $600,000 in their pocket.

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• Chrome does not re-draw properly on Windows 8

  - by Akshat Mittal

  There are a lot of problems with Chrome (24.0.1312.14 beta || But all this happened before update also) on Windows 8. Problems and explanations are listed below: Google Chrome re-draw time: When I switch tabs, the window retains the content of the previous tab and displays that even if I move my mouse, if only refreshes (re-draws) when there is a change on the webpage (like on hover) or I do a select all (or scroll). One thing to note is that the hover and select happens on the real page and not the retained image-like thing of the older webpage. Chrome is slow and laggy: Websites such as Facebook and Twitter (and more) have gone extremely laggy on Chrome (Win 8). When I was using Windows 7, I never experienced a lag or something. Also when using HTML-5 Websites, the transition (the -webkit-transition in CSS) goes extremely slow at times. Plugins Crash: Plugins like Flash Player, Shockwave Player, and more that are in-built into Chrome Crashes a lot, even when doing simple tasks like playing YouTube Videos, displaying ads or something. Chrome Crashes: Chrome has crashed over 100 times in the past month. Google Chrome just crashes randomly or I don't know the reason. Random Page crashes: Chrome results chrome://crash/(Copy-Paste this in address bar) on random pages even when the page is just loaded, I understand that this can happen on heavy HTML5 or JS websites but what about HTML only websites? Computer Freeze: Chrome sometimes, randomly, freezes my computer. Freeze in the sense, none of the other apps are also working. It's like the whole system freezes, I can not even switch to other apps. I am sure that this is because of Chrome since this happens only when Chrome is active. Most of the things above happens on Super User also, Super User never had any problem when using Chrome on Windows 7. UPDATE 1: @magicandre1981 Commented for trying to disable Hardware Acceleration. I tried it, it somewhat solved the problem but din't fix it. I am still experiencing all the above issues but less frequently (maybe because Chrome Restarted Completely) UPDATE 2: @avirk asked me to try a Stable Version of Chrome and Firefox, I din't experience any lag in Firefox, a little (negligible) lag in Chrome 22 (Maybe because its a new copy of Chrome, I haven't used it much). UPDATE 3: @NothingsImpossible said that He is also experiencing the same problem on Windows Server 2008! This seams to be a major issue now. He also said that GPU load is also high at the same time! Even I saw the same thing. UPDATE 4: Recently, Chrome updated to v24 Stable (I am using stable from a long time now). I was experiencing this problem a lot less in Chrome 23, but this is back in Chrome 24. Seams like Chrome 24 is the most affected from this bug, as this same problem was high in Chrome 24 beta also. UPDATE 5: Chrome was updated to v25 Stable. This problem is 99% Gone, it is still there in 1% of the cases. One such example is when I leave chrome inactive for a while with a few tabs open, the tabs go black and no activity can get them back to active state. If I open a new tab, the new tab is OK but the others are still black, I need to close all those tabs. UPDATE 6: Chrome updated to v27 Stable channel, this problem is nearly gone. This does happen occasionally, but not as frequent as in earlier versions of Chrome. UPDATE 7: I am on Chrome v35.0.1916.114 Stable, Windows 8.1 Pro Update 1. Some of the other problems appears to be back. Chrome is slow and laggy again. Re-draw time is getting worse. Is anybody else experiencing such issues? Does anybody have a solution to any of these?

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• Building a Data Mart with Pentaho Data Integration Video Review by Diethard Steiner, Packt Publishing

  - by Compudicted

  Originally posted on: http://geekswithblogs.net/Compudicted/archive/2014/06/01/building-a-data-mart-with-pentaho-data-integration-video-review-again.aspx The Building a Data Mart with Pentaho Data Integration Video by Diethard Steiner from Packt Publishing is more than just a course on how to use Pentaho Data Integration, it also implements and uses the principals of the Data Warehousing (and I even heard the name of Ralph Kimball in the video). Indeed, a video watcher should be familiar with its concepts as the Star Schema, Slowly Changing Dimension types, etc. so I suggest prior to watching this course to consider skimming through the Data Warehouse concepts (if unfamiliar) or even better, read the excellent Ralph’s The Data Warehouse Tooolkit. By the way, the author expands beyond using Pentaho along to MySQL and MonetDB which is a real icing on the cake! Indeed, I even suggest the name of the course should be ‘Building a Data Warehouse with Pentaho’. To successfully complete the course one needs to know some Linux (Ubuntu used in the course), the VI editor and the Bash command shell, but it seems that similar requirements would also apply to the Windows OS. Additionally, knowing some basic SQL would not hurt. As I had said, MonetDB is used in this course several times which seems to be not anymore complex than say MySQL, but based on what I read is very well suited for fast querying big volumes of data thanks to having a columnstore (vertical data storage). I don’t see what else can be a barrier, the material is very digestible. On this note, I must add that the author does not cover how to acquire the software, so here is what I found may help: Pentaho: the free Community Edition must be more than anyone needs to learn it. Or even go into a POC. MonetDB can be downloaded (exists for both, Linux and Windows) from http://goo.gl/FYxMy0 (just see the appropriate link on the left). The author seems to be using Eclipse to run SQL code, one can get it from http://goo.gl/5CcuN. To create, or edit database entities and/or schema otherwise one can use a universal tool called SQuirreL, get it from http://squirrel-sql.sourceforge.net.   Next, I must confess Diethard is very knowledgeable in what he does and beyond. However, there will be some accent heard to the user of the course especially if one’s mother tongue language is English, but it I got over it in a few chapters. I liked the rate at which the material is being presented, it makes me feel I paid for every second Eventually, my impressions are: Pentaho is an awesome ETL offering, it is worth learning it very much (I am an ETL fan and a heavy user of SSIS) MonetDB is nice, it tickles my fancy to know it more Data Warehousing, despite all the BigData tool offerings (Hive, Scoop, Pig on Hadoop), using the traditional tools still rocks Chapters 2 to 6 were the most fun to me with chapter 8 being the most difficult.   In terms of closing, I highly recommend this video to anyone who needs to grasp Pentaho concepts quick, likewise, the course is very well suited for any developer on a “supposed to be done yesterday” type of a project. It is for a beginner to intermediate level ETL/DW developer. But one would need to learn more on Data Warehousing and Pentaho, for such I recommend the 5 star Pentaho Data Integration 4 Cookbook. Enjoy it! Disclaimer: I received this video from the publisher for the purpose of a public review.

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• Building a Data Mart with Pentaho Data Integration Video Review by Diethard Steiner, Packt Publishing

  - by Compudicted

  Originally posted on: http://geekswithblogs.net/Compudicted/archive/2014/06/01/building-a-data-mart-with-pentaho-data-integration-video-review.aspx The Building a Data Mart with Pentaho Data Integration Video by Diethard Steiner from Packt Publishing is more than just a course on how to use Pentaho Data Integration, it also implements and uses the principals of the Data Warehousing (and I even heard the name of Ralph Kimball in the video). Indeed, a video watcher should be familiar with its concepts as the Star Schema, Slowly Changing Dimension types, etc. so I suggest prior to watching this course to consider skimming through the Data Warehouse concepts (if unfamiliar) or even better, read the excellent Ralph’s The Data Warehouse Tooolkit. By the way, the author expands beyond using Pentaho along to MySQL and MonetDB which is a real icing on the cake! Indeed, I even suggest the name of the course should be ‘Building a Data Warehouse with Pentaho’. To successfully complete the course one needs to know some Linux (Ubuntu used in the course), the VI editor and the Bash command shell, but it seems that similar requirements would also apply to the Weindows OS. Additionally, knowing some basic SQL would not hurt. As I had said, MonetDB is used in this course several times which seems to be not anymore complex than say MySQL, but based on what I read is very well suited for fast querying big volumes of data thanks to having a columnstore (vertical data storage). I don’t see what else can be a barrier, the material is very digestible. On this note, I must add that the author does not cover how to acquire the software, so here is what I found may help: Pentaho: the free Community Edition must be more than anyone needs to learn it. Or even go into a POC. MonetDB can be downloaded (exists for both, Linux and Windows) from http://goo.gl/FYxMy0 (just see the appropriate link on the left). The author seems to be using Eclipse to run SQL code, one can get it from http://goo.gl/5CcuN. To create, or edit database entities and/or schema otherwise one can use a universal tool called SQuirreL, get it from http://squirrel-sql.sourceforge.net.   Next, I must confess Diethard is very knowledgeable in what he does and beyond. However, there will be some accent heard to the user of the course especially if one’s mother tongue language is English, but it I got over it in a few chapters. I liked the rate at which the material is being presented, it makes me feel I paid for every second Eventually, my impressions are: Pentaho is an awesome ETL offering, it is worth learning it very much (I am an ETL fan and a heavy user of SSIS) MonetDB is nice, it tickles my fancy to know it more Data Warehousing, despite all the BigData tool offerings (Hive, Scoop, Pig on Hadoop), using the traditional tools still rocks Chapters 2 to 6 were the most fun to me with chapter 8 being the most difficult.   In terms of closing, I highly recommend this video to anyone who needs to grasp Pentaho concepts quick, likewise, the course is very well suited for any developer on a “supposed to be done yesterday” type of a project. It is for a beginner to intermediate level ETL/DW developer. But one would need to learn more on Data Warehousing and Pentaho, for such I recommend the 5 star Pentaho Data Integration 4 Cookbook. Enjoy it! Disclaimer: I received this video from the publisher for the purpose of a public review.

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• Do we still have a case against the goto statement? [closed]

  - by FredOverflow

  Possible Duplicate: Is it ever worthwhile using goto? In a recent article, Andrew Koenig writes: When asked why goto statements are harmful, most programmers will say something like "because they make programs hard to understand." Press harder, and you may well hear something like "I don't really know, but that's what I was taught." For that reason, I'd like to summarize Dijkstra's arguments. He then shows two program fragments, one without a goto and and one with a goto: if (n < 0) n = 0; Assuming that n is a variable of a built-in numeric type, we know that after this code, n is nonnegative. Suppose we rewrite this fragment: if (n >= 0) goto nonneg; n = 0; nonneg: ; In theory, this rewrite should have the same effect as the original. However, rewriting has changed something important: It has opened the possibility of transferring control to nonneg from anywhere else in the program. I emphasized the part that I don't agree with. Modern languages like C++ do not allow goto to transfer control arbitrarily. Here are two examples: You cannot jump to a label that is defined in a different function. You cannot jump over a variable initialization. Now consider composing your code of tiny functions that adhere to the single responsibility principle: int clamp_to_zero(int n) { if (n >= 0) goto n_is_not_negative: n = 0; n_is_not_negative: return n; } The classic argument against the goto statement is that control could have transferred from anywhere inside your program to the label n_is_not_negative, but this simply is not (and was never) true in C++. If you try it, you will get a compiler error, because labels are scoped. The rest of the program doesn't even see the name n_is_not_negative, so it's just not possible to jump there. This is a static guarantee! Now, I'm not saying that this version is better then the one without the goto, but to make the latter as expressive as the first one, we would at least have to insert a comment, or even better yet, an assertion: int clamp_to_zero(int n) { if (n < 0) n = 0; // n is not negative at this point assert(n >= 0); return n; } Note that you basically get the assertion for free in the goto version, because the condition n >= 0 is already written in line 1, and n = 0; satisfies the condition trivially. But that's just a random observation. It seems to me that "don't use gotos!" is one of those dogmas like "don't use multiple returns!" that stem from a time where the real problem were functions of hundreds or even thousand of lines of code. So, do we still have a case against the goto statement, other than that it is not particularly useful? I haven't written a goto in at least a decade, but it's not like I was running away in terror whenever I encountered one. 1 Ideally, I would like to see a strong and valid argument against gotos that still holds when you adhere to established programming principles for clean code like the SRP. "You can jump anywhere" is not (and has never been) a valid argument in C++, and somehow I don't like teaching stuff that is not true. 1: Also, I have never been able to resurrect even a single velociraptor, no matter how many gotos I tried :(

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• When is your interview?

  - by Rob Farley

  Sometimes it’s tough to evaluate someone – to figure out if you think they’d be worth hiring. These days, since starting LobsterPot Solutions, I have my share of interviews, on both sides of the desk. Sometimes I’m checking out potential staff members; sometimes I’m persuading someone else to get us on board for a project. Regardless of who is on which side of the desk, we’re both checking each other out. The world is not how it was some years ago. I’m pretty sure that every time I walk into a room for an interview, I’ve searched for them online, and they’ve searched for me. I suspect they usually have the easier time finding me, although there are obviously other Rob Farleys in the world. They may have even checked out some of my presentations from conferences, read my blog posts, maybe even heard me tell jokes or sing. I know some people need me to explain who I am, but for the most part, I think they’ve done plenty of research long before I’ve walked in the room. I remember when this was different (as it could be for you still). I remember a time when I dealt with recruitment agents, looking for work. I remember sitting in rooms having been giving a test designed to find out if I knew my stuff or not, and then being pulled into interviews with managers who had to find out if I could communicate effectively. I’d need to explain who I was, what kind of person I was, what my value-system involved, and so on. I’m sure you understand what I’m getting at. (Oh, and in case you hadn’t realised, it’s a T-SQL Tuesday post, this month about interviews.) At TechEd Australia some years ago (either 2009 or 2010 – I forget which), I remember hearing a comment made during the ‘locknote’, the closing session. The presenter described a conversation he’d heard between two girls, discussing a guy that one of them had just started dating. The other girl expressed horror at the fact that her friend had met this guy in person, rather than through an online dating agency. The presenter pointed out that people realise that there’s a certain level of safety provided through the checks that those sites do. I’m not sure I completely trust this, but I’m sure it’s true for people’s technical profiles. If I interview someone, I hope they have a profile. I hope I can look at what they already know. I hope I can get samples of their work, and see how they communicate. I hope I can get a feel for their sense of humour. I hope I already know exactly what kind of person they are – their value system, their beliefs, their passions. Even their grammar. I can work out if the person is a good risk or not from who they are online. If they don’t have an online presence, then I don’t have this information, and the risk is higher. So if you’re interviewing with me, your interview started long before the conversation. I hope it started before I’d ever heard of you. I know the interview in which I’m being assessed started before I even knew there was a product called SQL Server. It’s reflected in what I write. It’s in the way I present. I have spent my life becoming me – so let’s talk! @rob_farley

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• surviveFocusChange=true

  - by Geertjan

  Here's a very cool thing that I keep forgetting about but that Jesse reminded me of in the recent blog entries on Undo/Redo: "surviveFocusChange=true". Look at the screenshot below. You see two windows with a toolbar button. The toolbar button is enabled whenever an object named "Bla" is in the Lookup. The "Demo" window has a "Bla" object in its Lookup and hence the toolbar button is enabled when the focus is in the "Demo" window, as shown below: Now the focus is in the "Output" window, which does not have a "Bla" object in its Lookup and hence the button is disabled: However, there are scenarios where you might like the button to remain enabled even when the focus changes. (One such scenario is the Undo/Redo scenario in this blog a few days ago, i.e., even when the Properties window has the focus the Undo/Redo buttons should be enabled.) Here you can see that the button is enabled even though the focus has switched to the "Output" window: How to achieve this? Well, you need to register your Action to have "surviveFocusChange" set to "true". It is, by default, set to "false": import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import org.openide.awt.ActionID; import org.openide.awt.ActionReference; import org.openide.awt.ActionReferences; import org.openide.awt.ActionRegistration; import org.openide.util.NbBundle.Messages; @ActionID(category = "File", id = "org.mymodule.BlaAction") @ActionRegistration(surviveFocusChange=true, iconBase = "org/mymodule/Datasource.gif", displayName = "#CTL_BlaAction") @ActionReferences({     @ActionReference(path = "Toolbars/Bla", position = 0) }) @Messages("CTL_BlaAction=Bla") public final class BlaAction implements ActionListener {     private final Bla context;     public BlaAction(Bla context) {         this.context = context;     }     @Override     public void actionPerformed(ActionEvent ev) {         // TODO use context     } } That's all. Now folders and files will be created in the NetBeans Platform filesystem from the annotations above when the module is compiled such that the NetBeans Platform will automatically keep the button enabled even when the user switches focus to a window that does not contain a "Bla" object in its Lookup. Hence, the same "Bla" object will remain available when switching from one window to another, until a new "Bla" object will be made available in the Lookup.

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• What Counts For A DBA: ESP

  - by Louis Davidson

  Now I don’t want to get religious here, and I’m not going to, but what I’m going to describe in this ‘What Counts for a DBA’ installment sometimes feels like magic. Often  I will spend hours thinking about the solution to a design issue or coding problem, working diligently to try to come up with a solution and then finally just give up with the feeling that I’m not even qualified to be a data entry clerk, much less a data architect.  At this point I often take a walk (or sometimes a nap), and then it hits me. I realize that I have the answer just sitting in my brain, ready to implement.  This phenomenon is not limited to walks either; it can happen almost any time after I stop my obsession about a problem. I call this phenomena ESP (or Extra-Sensory Programming.)  Another term for this could be ‘sleeping on it’, and while the idiom tends to mean to let time pass to actively think about a problem, sleeping on a problem also lets you relax and let your brain do the work. I first noticed this back in my college days when I would play video games for hours on end. We would get stuck deep in some dungeon unable to find a way out, playing for days on end until we were beaten down tired. Once we gave up and walked away, the solution would usually be there waiting for one of us before we came back to play the next day.  Sometimes it would be in the form of a dream, and sometimes it would just be that the problem was now easy to solve when we started to play again.  While it worked great for video games, it never occurred when I studied English Literature for hours on end, or even when I worked for the same sort of frustrating hours attempting to solve a homework problem in Calculus.  I believe that the difference was that I was passionate about the video game, and certainly far less so about homework where people used the word “thou” instead of “you” or x to represent a number. This phenomenon occurs somewhat more often in my current work as a professional data programmer, because I am very passionate about SQL and love those aspects of my career choice.  Every day that I get to draw a new data model to solve a customer issue, or write a complex SELECT statement to ferret out the answer to a complex data question, is a great day. I hope it is the same for any reader of this blog.  But, unfortunately, while the day on a whole is great, a heck of a lot of noise is generated in work life. There are the typical project deadlines, along with the requisite project manager sitting on your shoulders shouting slogans to try to make you to go faster: Add in office politics, and the occasional family issues that permeate the mind, and you lose the ability to think deeply about any problem, not to mention occasionally forgetting your own name.  These office realities coupled with a difficult SQL problem staring at you from your widescreen monitor will slowly suck the life force out of your body, making it seem impossible to solve the problem This is when the walk starts; or a nap. Maybe you hide from the madness under your desk like George Costanza hides from Steinbrenner on Seinfeld.  Forget about the problem. Free your mind from the insanity of the problem and your surroundings. Then let your training and education deep in your brain take over and see if it will passively do the rest for you. If you don’t end up with a solution, the worst case scenario is that you have a bit of exercise or rest, and you won’t have heard the phrase “better is the enemy of good enough” even once…which certainly will do your brain some good. Once you stop expecting whipping your brain for information, inspiration may just strike and instead of a humdrum solution you find a solution you hadn’t even considered, almost magically. So, my beloved manager, next time you have an urgent deadline and you come across me taking a nap, creep away quietly because I’m working, doing some extra-sensory programming.

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• Hyper-V Live Migration across Sites!

  - by Ryan Roussel

  One of the great sessions I sat in on at Tech Ed this week was stretching a Windows 2008 R2 Hyper-V  Failover Cluster across sites.  With this ability, you could actually implement a Hyper-V cluster where you could migrate or even Live Migrate VMs across sites.   With this area’s propensity for Hurricanes, this will be a very popular topic for me over the next few months. While this technology is possible today, it’s also very complicated and can be very expensive to implement.    First your WAN connection has to support the ability to trunk your VLAN across both sites in order to Live Migrate.  This means you can’t use a Layer 3 routed connection like MPLS.  It has to be a Metro Ethernet connection or "Dark Fiber”.  Dark Fiber is unused Fiber already in the ground that can be leased from  various providers. Both of these connections would allow you to trunk layer 2 across your WAN.  Cisco does have the ability to trunk layer 2 across a routed connection by muxing the traffic but this is only available in their Nexus product line which has a very steep price tag.   If you are stuck with MPLS or the like and Nexus switching is not a realistic possibility, you will have to implement a multi-subnet cluster in which case Live Migration won’t be possible.  However you can still failover VMs to the remote site with some planning and manual intervention.  The consideration here is that the VMs will be on a different subnet once migrated, so you will have to change the IP addressing of your VMs.  This also has ramifications with DNS and Name resolution to control your down time.  DHCP with Reservations for your VMs is the preferred method to achieve the IP changes as this will automate that part of the process.   Secondly, you will have to have  a mechanism to replicate your storage across both sites.  Many SAN vendors natively support hardware based synchronous and asynchronous replication.  Some even support cluster shared volumes which were introduced in 2008 R2.   If your SANs do not support this natively, there are alternative file based replication products either software based like Double Take or hardware appliance like EMC.  Be sure to check with your vendor on the support of Disk majority if you’re replicating your quorum disk between SANs.   The last consideration is the ability to maintain quorum for your cluster.  If your replication provider does not support Disk Majority through replication, you will have to explore Node Majority with File Share Witness.  This will affect your design as a 3 node cluster with 1 node at the remote site and FSW at the production site would not have the ability to maintain quorum if the production site was lost. MS best practice for this would be to implement an even node cluster with 2 nodes at  each site and the FSW at a third site.   And there you have it.  While some considerations and research goes into implementing this solution, even a multi-subnet solution would be invaluable to organizations in the implementations of “warm” DR sites.

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• Is It Worth It To Learn Experimental Languages

  - by Xander Lamkins

  I'm a young programmer who desires to work in the field someday as a programmer. I know Java, VB.NET and C#. I want to learn a new language (as I programmer, I know that it is valuable to extend what I know - to learn languages that make you think differently). I took a look online to see what languages were common. Everybody knows C and C++ (even those muggles who know so little about computers in general), so I thought, maybe I should push for C. C and C++ are nice but they are old. Things like Haskell and Forth (etc. etc. etc.) are old and have lost their popularity. I'm scared of learning C (or even C++) for this same reason. Java is pretty old as well and is slow because it's run by the JVM and not compiled to native code. I've been a Windows developer for quite a while. I recently started using Java - but only because it was more versatile and spreadable to other places. The problem is that it doesn't look like a very usable language for these reasons: It's most used purpose is for web application and cellphone apps (specifically Android) As far as actual products made with it, the only things that come to mind are Netbeans, Eclipse (hurrah for making and IDE with the language the IDE is for - it's like making a webpage for writing HTML/CSS/Javascript), and Minecraft which happens to be fun but laggy and bipolar as far as computer spec. support. Other than that it's used for servers but heck - I don't only want to make/configure servers. The .NET languages are nice, however: People laugh if I even mention VB.NET or C# in a serious conversation. It isn't cross-platform unless you use MONO (which is still in development and has some improvements to be made). Lacks low level stuff because, like Java with the JVM, it is run/managed by the CLR. My first thought was learning something like C and then using it to springboard into C++ (just to make sure I would have a strong understanding/base), but like I said earlier, it's getting older and older by the minute. What I've Looked Into Fantom looks nice. It's like a nice middleman between my two favorite languages and even lets me publish between the two interchangeably, but, unlike what I want, it compiles to the CLR or JVM (depending on what you publish it to) instead of it being a complete compile. D also looks nice. It seems like a very usable language and from multiple sources it appears to actually be better than C/C++. I would jump right with it, but I'm still unsure of its success because it obviously isn't very mainstream at this point. There are a couple others that looked pretty nice that focused on other things such as Opa with web development and Go by GOOGLE. My Question Is it worth learning these "experimental" languages? I've read other questions that say that if you aren't constantly learning languages and open to all languages that you aren't in the right mindset for programming. I understand this and I still might not quite be getting it, but in truth, if a language isn't going to become mainstream, should I spend my time learning something else? I don't want to learn old (or any going to soon be old) programming languages. I know that many people see this as something important, *but would any of you ever actually consider (assuming you didn't already know) FORTRAN? My goal is to stay current to make sure I'm successful in the future. Disclaimer Yes, I am a young programmer, so I probably made a lot of naive statements in my question. Feel free to correct me on ANYTHING! I have to start learning somewhere so I'm sure a lot of my knowledge is sketchy enough to have caused to incorrect statements or flaws in my thinking. Please leave any feelings you have in the comments.

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• Is it worth to learn Experimental Languages?

  - by Xander Lamkins

  I'm a young programmer who desires to work in the field someday as a programmer. I know Java, VB.NET and C#. I want to learn a new language (as I programmer, I know that it is valuable to extend what I know - to learn languages that make you think differently). I took a look online to see what languages were common. Everybody knows C and C++ (even those muggles who know so little about computers in general), so I thought, maybe I should push for C. C and C++ are nice but they are old. Things like Haskell and Forth (etc. etc. etc.) are old and have lost their popularity. I'm scared of learning C (or even C++) for this same reason. Java is pretty old as well and is slow because it's run by the JVM and not compiled to native code. I've been a Windows developer for quite a while. I recently started using Java - but only because it was more versatile and spreadable to other places. The problem is that it doesn't look like a very usable language for these reasons: It's most used purpose is for web application and cellphone apps (specifically Android) As far as actual products made with it, the only things that come to mind are Netbeans, Eclipse (hurrah for making and IDE with the language the IDE is for - it's like making a webpage for writing HTML/CSS/Javascript), and Minecraft which happens to be fun but laggy and bipolar as far as computer spec. support. Other than that it's used for servers but heck - I don't only want to make/configure servers. The .NET languages are nice, however: People laugh if I even mention VB.NET or C# in a serious conversation. It isn't cross-platform unless you use MONO (which is still in development and has some improvements to be made). Lacks low level stuff because, like Java with the JVM, it is run/managed by the CLR. My first thought was learning something like C and then using it to springboard into C++ (just to make sure I would have a strong understanding/base), but like I said earlier, it's getting older and older by the minute. What I've Looked Into Fantom looks nice. It's like a nice middleman between my two favorite languages and even lets me publish between the two interchangeably, but, unlike what I want, it compiles to the CLR or JVM (depending on what you publish it to) instead of it being a complete compile. D also looks nice. It seems like a very usable language and from multiple sources it appears to actually be better than C/C++. I would jump right with it, but I'm still unsure of its success because it obviously isn't very mainstream at this point. There are a couple others that looked pretty nice that focused on other things such as Opa with web development and Go by GOOGLE. My Question Is it worth learning these "experimental" languages? I've read other questions that say that if you aren't constantly learning languages and open to all languages that you aren't in the right mindset for programming. I understand this and I still might not quite be getting it, but in truth, if a language isn't going to become mainstream, should I spend my time learning something else? I don't want to learn old (or any going to soon be old) programming languages. I know that many people see this as something important, *but would any of you ever actually consider (assuming you didn't already know) FORTRAN? My goal is to stay current to make sure I'm successful in the future. Disclaimer Yes, I am a young programmer, so I probably made a lot of naive statements in my question. Feel free to correct me on ANYTHING! I have to start learning somewhere so I'm sure a lot of my knowledge is sketchy enough to have caused to incorrect statements or flaws in my thinking. Please leave any feelings you have in the comments.

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• Know your Data Lineage

  - by Simon Elliston Ball

  An academic paper without the footnotes isn’t an academic paper. Journalists wouldn’t base a news article on facts that they can’t verify. So why would anyone publish reports without being able to say where the data has come from and be confident of its quality, in other words, without knowing its lineage. (sometimes referred to as ‘provenance’ or ‘pedigree’) The number and variety of data sources, both traditional and new, increases inexorably. Data comes clean or dirty, processed or raw, unimpeachable or entirely fabricated. On its journey to our report, from its source, the data can travel through a network of interconnected pipes, passing through numerous distinct systems, each managed by different people. At each point along the pipeline, it can be changed, filtered, aggregated and combined. When the data finally emerges, how can we be sure that it is right? How can we be certain that no part of the data collection was based on incorrect assumptions, that key data points haven’t been left out, or that the sources are good? Even when we’re using data science to give us an approximate or probable answer, we cannot have any confidence in the results without confidence in the data from which it came. You need to know what has been done to your data, where it came from, and who is responsible for each stage of the analysis. This information represents your data lineage; it is your stack-trace. If you’re an analyst, suspicious of a number, it tells you why the number is there and how it got there. If you’re a developer, working on a pipeline, it provides the context you need to track down the bug. If you’re a manager, or an auditor, it lets you know the right things are being done. Lineage tracking is part of good data governance. Most audit and lineage systems require you to buy into their whole structure. If you are using Hadoop for your data storage and processing, then tools like Falcon allow you to track lineage, as long as you are using Falcon to write and run the pipeline. It can mean learning a new way of running your jobs (or using some sort of proxy), and even a distinct way of writing your queries. Other Hadoop tools provide a lot of operational and audit information, spread throughout the many logs produced by Hive, Sqoop, MapReduce and all the various moving parts that make up the eco-system. To get a full picture of what’s going on in your Hadoop system you need to capture both Falcon lineage and the data-exhaust of other tools that Falcon can’t orchestrate. However, the problem is bigger even that that. Often, Hadoop is just one piece in a larger processing workflow. The next step of the challenge is how you bind together the lineage metadata describing what happened before and after Hadoop, where ‘after’ could be  a data analysis environment like R, an application, or even directly into an end-user tool such as Tableau or Excel. One possibility is to push as much as you can of your key analytics into Hadoop, but would you give up the power, and familiarity of your existing tools in return for a reliable way of tracking lineage? Lineage and auditing should work consistently, automatically and quietly, allowing users to access their data with any tool they require to use. The real solution, therefore, is to create a consistent method by which to bring lineage data from these data various disparate sources into the data analysis platform that you use, rather than being forced to use the tool that manages the pipeline for the lineage and a different tool for the data analysis. The key is to keep your logs, keep your audit data, from every source, bring them together and use the data analysis tools to trace the paths from raw data to the answer that data analysis provides.

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• What Counts For a DBA – Depth

  - by Louis Davidson

  SQL Server offers very simple interfaces to many of its features. Most people could open up SSMS, connect to a server, write a simple query and see the results. Even several of the core DBA tasks are deceptively straightforward. It doesn’t take a rocket scientist to perform a basic database backup or run a trace (even using the newfangled Extended Events!). However, appearances can be deceptive, and often times it is really important that a DBA understands not just the basics of how to perform a task, but why we do a task, and how that task works. As an analogy, consider a child walking into a darkened room. Most would know that they need to turn on the light, and how to do it, so they flick the switch. But what happens if light fails to shine forth. Most would immediately tell you that you need to consider changing the light bulb. So you hop in the car and take them to the local home store and instruct them to buy a replacement. Confronted with a 40 foot display of light bulbs, how will they decide which of the hundreds of types of bulbs, of different types, fittings, shapes, colors, power and efficiency ratings, is the right choice? Obviously the main lesson the child is going to learn this day is how to use their cell phone as a flashlight so they don’t have to ask for help the next time. Likewise, when the metaphorical toddlers who use your database server have issues, they will instinctively know something is wrong, and may even have some idea what caused it, but will have no depth of knowledge to figure out the right solution. That is where the DBA comes in and attempts to save the day. However, when one looks beneath the shiny UI, SQL Server has its own “40 foot display of light bulbs”, in the form of the tremendous number of tools and the often-bewildering amount of information they can present to the DBA, to help us find issues. Unfortunately, resorting to guesswork, to trying different “bulbs” over and over, hoping to stumble on the answer. This is where the right depth of knowledge goes a long way. If we need to write a SELECT statement, then knowing the syntax and where to find the data is not enough. Knowledge of indexes and query plans is essential. Without it, we might hit on a query that “works”, but we are basically still a user, not a programmer, because we have no real control over our platform. Is that level of knowledge deep enough? Probably not, since knowledge of the underlying metadata and structures would be very useful in helping us make sense of any query plan. Understanding the structure of an index makes the “key lookup” operator not sound like what you do when someone tapes your car key to the ceiling. So is even this level of understanding deep enough? Do we need to understand the memory architecture used to process the query? It might be a comforting level of knowledge, and will doubtless come in handy at some point, but is not strictly necessary in most cases. Beyond that lies (more or less) full knowledge of SQL language and the intricacies of every step the SQL Server engine takes to process our query. My personal theory is that, as a professional, our knowledge of a given task should extend, at a minimum, one level deeper than is strictly necessary to perform the task. Anything deeper can be left to the ridiculously smart, or obsessive, or both. As an example. tasked with storing an integer value between 0 and 99999999, it’s essential that I know that choosing an Integer over Decimal(8,0) will likely offer performance benefits. It is then useful that I also understand the value of adding a CHECK constraint, to make sure the values are valid to the desired range; and comforting that I know a little about the underlying processors, registers and computer math. Anything further, I leave to the likes of Joe Chang, whose recent blog post on the topic offers depth by the bucketful!  

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• Software and/(x)or Hardware Projects for Pre-School Kids

  - by haylem

  I offered to participate at my kid's pre-school for various activities (yes, I'm crazy like that), and one of them is to help them discover extra-curricular (big word for a pre-school, but by lack of a better one... :)) hobbies, which may or may not relate to a professional activity. At first I thought that it wouldn't be really easy to have pre-schoolers relate to programming or the internal workings of a computer system in general (and I'm more used to teaching middle-school to university-level students), but then I thought there must be a way. So I'm trying to figure out ways to introduce very young kids (3yo) to computer systems in a fun and preferably educational way. Of course, I don't expect them to start smashing the stack for fun and profit right away (or at least not voluntarily, though I could use the occasion for some toddler tests...), but I'm confident there must be ways to get them interested in both: using the systems, becoming curious about understanding what they do, interacting with the systems to modify them. I guess this setting is not really relevant after all, it's pretty much the same as if you were aiming to achieve the same for your own kids at home. Ideas Considering we're talking 3yo pre-schoolers here, and that at this age some kids are already quite confident using a mouse (some even a keyboard, if not for typing, at least to press some buttons they've come to associate with actions) while others have not yet had any interaction with computers of any kind, it needs to be: rather basic, demonstrated and played with in less then 5 or 10 minutes, doable in in groups or alone, scalable and extendable in complexity to accommodate their varying abilities. The obvious options are: basic smallish games to play with, interactive systems like LOGO, Kojo, Squeak and clones (possibly even simpler than that), or thngs like Lego Systems. I guess it can be a thing to reflect on both at the software and the hardware levels: it could be done with a desktop or laptop machine, a tablet, a smartphone (or a crap-phone, for that matter, as long as you can modify it), or even get down to building something from scratch (Raspberry Pi and Arduino being popular options at the moment). I can probably be in the form of games, funny visualizations (which are pretty much games) w/ Prototype, virtual worlds to explore. I also thought on the moment (and I hope this won't offend anyone) that some approaches to teaching pets could work (reward systems, haptic feedback and such things could quickly point a kid in the right direction to understanding how things work, in a similar fashion - I'm not suggesting to shock the kids!). Hmm, Is There an Actual Question in There? What type of systems do you think might be a good fit, both in terms of hardware and software? Do you have seen such systems, or have anything in mind to work on? Are you aware of some research in this domain, with tangible results? Any input is welcome. It's not that I don't see options: there are tons, but I have a harder time pinpointing a more concrete and definite type of project/activity, so I figure some have valuable ideas or existing ones. Note: I am not advocating that every kid should learn to program, be interested in computer systems, or that all of them in a class would even care enough to follow such an introduction with more than a blank stare. I don't buy into the "everybody would benefit from learning to program" thing. Wouldn't hurt, but not necessary in any way. But if I can walk out of there with a few of them having smiled using the thing (or heck, cried because others took them away from them), that'd be good enough. Related Questions I've seen and that seem to complement what I'm looking for, but not exactly for the same age groups or with the same goals: Teaching Programming to Kids Recommendations for teaching kids math concepts & skills for programming?

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• The HTTP verb POST used to access path '/' is not allowed.

  - by Ryan

  The entire error: Server Error in '/' Application. The HTTP verb POST used to access path '/' is not allowed. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Web.HttpException: The HTTP verb POST used to access path '/' is not allowed. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [HttpException (0x80004005): The HTTP verb POST used to access path '/' is not allowed.] System.Web.DefaultHttpHandler.BeginProcessRequest(HttpContext context, AsyncCallback callback, Object state) +2871966 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8679410 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 To be honest, I'm not even sure where the error came from. I'm running Visual Studio 2008 through the Virtual Server. I just put a button: <asp:Button ID="btnRegister" runat="server" Text="Register" CssClass="bt_register" onclick="btnRegister_Click" /> On a login user control, the onclick event is just a simple response.redirect Response.Redirect("~/register.aspx"); Debugging the project, it isn't even hitting the btnRegister_Click method anyway. I'm not sure where to even begin with debugging this error. Any information will help. I can post all the code I have, but like I said, I'm not sure where this error is even being thrown at. Edit It has nothing at all to do with the button click event. I got rid of the method and the onclick parameter on the aspx page. Still coming up with the same error problem found Okay so this is for a school project and its a group project. Some one in my group thought it would be a good idea to wrap a form tag around this area telling it to post. Found it doing a diff with a revision on Google code.

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• Roadmap to Android development

  - by Matthew

  Hello, I've done a little research, and am interested in developing for Android. I've never programmed before, and have no idea how to go from zero experience to developing for a mobile device. My interest is in eventually making some sort of 2d game. Is there a lesson plan for starting from the ground up? I would think one would need to learn the Java language to start. Looking at the Sun website, it's a bit daunting. Is there a book, specifically, that would wrap up this knowledge in a bit of a directed lesson plan? I'm not sure if opengl-es is what would be required for 2d games. I've done a little research on this, and it's even far more daunting than Java itself. I can't even begin to figure out where to start with even just opengl, sans -es. My best guess would be that I need further knowledge in Java to continue with this, but even still, is it possible to learn concurrently with Java?

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• Using Taylor Series to Avoid Loss of Precision

  - by Zachary

  I'm trying to use Taylor series to develop a numerically sound algorithm for solving a function. I've been at it for quite a while, but haven't had any luck yet. I'm not sure what I'm doing wrong. The function is f(x)=1 + x - sin(x)/ln(1+x) x~0 Also: why does loss of precision even occur in this function? when x is close to zero, sin(x)/ln(1+x) isn't even close to being the same number as x. I don't see where significance is even being lost. In order to solve this, I believe that I will need to use the Taylor expansions for sin(x) and ln(1+x), which are x - x^3/3! + x^5/5! - x^7/7! + ... and x - x^2/2 + x^3/3 - x^4/4 + ... respectfully. I have attempted to use like denominators to combine the x and sin(x)/ln(1+x) components, and even to combine all three, but nothing seems to work out correctly in the end. Any help is appreciated.

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• Why are floating point values so prolific?

  - by Kibbee

  So, title says it all. Why are floating point values so prolific in computer programming. Due to problems like rounding errors, and not being able to even accurately represent numbers such as 0.1, I really can't see how they got as far as they did. I understand that the computation is faster with floating point numbers, however, I can think of only a few cases that they actually the right data type would be using. If you sat back and think about every time you used a floating point value, how many times did you say, well, some error would be ok, as long as the result was a few microseconds faster. It really makes me think because Jeff was talking about NP completeness, and how heuristics give an answer that is kind of right. And well, computers shouldn't do that. They should give you the answer that is correct. Yet we see floating point values used in many applications where they are completely not valid. What really bugs me, isn't that floating point exists, but that in many languages, there isn't even a viable alternative, non-floating point, decimal value. A lot of programmers when doing financial applications have to fall back to storing the number of cents in an integer field. Which brings with it all kinds of other problems. Why do floats continue to be so prolific, even though they can't represent the real answer, and we expect computers to be accurate? [EDIT] Just to clarify, I was talking about Base 2 floating points, and not base 10 floating points. .Net offers the Decimal data type, which is a base 10 floating point value which offers a much better representation of the numbers we deal with on a daily basis in most computer programs. I find it hard to believe that even modern languages like Java don't support base 10 floating point values, unless you want to move into the realm of things like BigDecimal, which isn't really the right answer either in a lot of situations.

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• Advice on improving programming skills, learning capabilities?

  - by anonymous-coward1234

  Hi all, After 2,5 years of professional Java programing, I still have problems that make my job difficult and, more importantly - more times that I would like to admit - not enjoyable. I would like to ask for advice by more experienced people on ways that would help me overcome them. These are the problems I have: I do not absorb new knowledge easily. Even when I understand something, after a couple of days I easily forget even basic stuff. Other co-workers, even with the same working experience, when reading new technologies put things easily into "context", and are able to compare in "real time| similar technologies they already have used. I always try to address all the issues to whatever I am doing at one go, which results in me trying to resolve too many problems at the same time, losing completely control. I find it difficult to make my mind on a single problem that I should address first, and even when I do, and find myself throwing away code that I wrote because I started addressing the wrong issue first. As far as architecture and data modeling is concerned, I have difficulty making decisions on what objects must be created, with what hierarchy, interfaces, abstraction etc. I imagine that - to a certain degree - these things come with experience. But after 2,5 years of Java programming, I would expect myself to have come much farther that I have come, both in terms of absorption and experience. Is there a way to improve my learning speed? Any books, methods, advice is welcome.

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• Help, my CentOS servers keep going down , No route to host after a random uptime [closed]

  - by user249071

  Hello , I have a couple of Centos linux servers, that have a very simple task, they run nginx + fastcgi for php , and some NFS mounts between them, readonly They have some RPC commands to start some downloading processes with wget, nothing fancy , from a main server, but their behavior is very unstable, they simply go down, we tried to monitor ram , processor usage, even network connections, they don't load up so much, max network connections up to... 250 max, 15% processor usage and memory , well, doesn't even fill up, 2.5GB from 8GB max , I have no ideea why can a linux server go down like that, they aren't even public servers, no domain names installed no public serving, for sites. The only thing that I've discovered was that if i didn't restart the network service every couple of hours or so... the servers were becoming very slow, starting apps very slow, but not repoting a high usage of resources...Maybe Centos doesn't free the timeout connections, or something like that...It's based on Red Hat right? I'm not a linux expert , but I'm sure that there are a few guys out there that can easily have an answer to this , or even have some leads to what i can do ... I haven't installed snort, or other things to view if we have some DOS attacks, still the scheduled script that restarts the network each hour should put the system back online, and it doesn't.... Thank you in advance

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• How would I code a complex formula parser manually?

  - by StormianRootSolver

  Hm, this is language - agnostic, I would prefer doing it in C# or F#, but I'm more interested this time in the question "how would that work anyway". What I want to accomplish ist: a) I want to LEARN it - it's about my ego this time, it's for a fun project where I want to show myself that I'm a really good at this stuff b) I know a tiny little bit about EBNF (although I don't know yet, how operator precedence works in EBNF - Irony.NET does it right, I checked the examples, but this is a bit ominous to me) c) My parser should be able to take this: 5 * (3 + (2 - 9 * (5 / 7)) + 9) for example and give me the right results d) To be quite frankly, this seems to be the biggest problem in writing a compiler or even an interpreter for me. I would have no problem generating even 64 bit assembler code (I CAN write assembler manually), but the formula parser... e) Another thought: even simple computers (like my old Sharp 1246S with only about 2kB of RAM) can do that... it can't be THAT hard, right? And even very, very old programming languages have formula evaluation... BASIC is from 1964 and they already could calculate the kind of formula I presented as an example f) A few ideas, a few inspirations would be really enough - I just have no clue how to do operator precedence and the parentheses - I DO, however, know that it involves an AST and that many people use a stack So, what do you think?

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• Facebook not recoginising open graph tags

  - by Pratik Poddar

  My object page looks like: <html xmlns="http://www.w3.org/1999/xhtml" dir="ltr" lang="en-US" xmlns:fb="https://www.facebook.com/2008/fbml"> <head prefix="og: http://ogp.me/ns# cliprin: http://ogp.me/ns/apps/cliprin#"> <meta property="fb:app_id" content="143944345745133" /> <meta property="og:type" content="cliprin:product" /> <meta property="og:url" content="https://itsourstudio.com/" /> <meta property="og:title" content="LED Ice Cubes (Set Of 4)" /> <meta property="og:sitename" content="Its Our Studio" /> <meta property="og:image" content="https://s-static.ak.fbcdn.net/images/devsite/attachment_blank.png" /> <meta property="og:description" content="Blah Blah Blah" /> </head> </html> The JSLink Debugger of the page as shown by the link shows that of:type is website and gives following warnings: Open Graph Warnings That Should Be Fixed Inferred Property: The 'og:url' property should be explicitly provided, even if a value can be inferred from other tags. Inferred Property: The 'og:title' property should be explicitly provided, even if a value can be inferred from other tags. Inferred Property: The 'og:description' property should be explicitly provided, even if a value can be inferred from other tags. Inferred Property: The 'og:image' property should be explicitly provided, even if a value can be inferred from other tags. Tiny og:image: All the images referenced by og:image must be at least 200px in both dimensions. Please check all the images with tag og:image in the given url and ensure that it meets the minimum specification.

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• Qt application crashing immediately without debugging info. How do I track down the problem?

  - by jjacksonRIAB

  I run an Qt app I've built: ./App Segmentation fault I run it with strace: strace ./App execve("./App", ["./App"], [/* 27 vars */]) = 0 --- SIGSEGV (Segmentation fault) @ 0 (0) --- +++ killed by SIGSEGV +++ Process 868 detached Again, no useful info. I run it with gdb: (gdb) run Starting program: /root/test/App Reading symbols from shared object read from target memory...(no debugging symbols found)...done. Loaded system supplied DSO at 0xffffe000 Program received signal SIGSEGV, Segmentation fault. 0x00000001 in ?? () Again, nothing. I run it with valgrind: ==948== Process terminating with default action of signal 11 (SIGSEGV) ==948== Bad permissions for mapped region at address 0x0 ==948== at 0x1: (within /root/test/App) Even if I put in debugging symbols, it doesn't give any more useful info. ldd shows all libraries being linked properly. Is there any other way I can find out what's wrong? I can't even do standard printf, cout, etc debugging. The executable doesn't even seem to start running at all. I rebuilt with symbols, and tried the suggestion below (gdb) break main Breakpoint 1 at 0x45470 (gdb) run Starting program: /root/test/App Breakpoint 1 at 0x80045470 Reading symbols from shared object read from target memory...done. Loaded system supplied DSO at 0xffffe000 Program received signal SIGSEGV, Segmentation fault. 0x00000001 in ?? () I checked for static initializers and I don't seem to have any. Yep, I tried printf, cout, etc. It doesn't even make it into the main routine, so I'm looking for problems with static initializers in link libraries, adding them in one-by-one. I'm not getting any stack traces either.

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• What makes you trust that a piece of open source software is not malicious?

  - by Daniel DiPaolo

  We developers are in a unique position when it comes to the ability to not only be skeptical about the capabilities provided by open source software, but to actively analyze the code since it is freely available. In fact, one may even argue that open source software developers have a social responsibility to do so to contribute to the community. But at what point do you as a developer say, "I better take a look at what this is doing before I trust using it" for any given thing? Is it a matter of trusting code with your personal information? Does it depend on the source you're getting it from? What spurred this question on was a post on Hacker News to a javascript bookmarklet that supposedly tells you how "exposed" your information on Facebook is as well as recommending some fixes. I thought for a second "I'd rather not start blindly running this code over all my (fairly locked down) Facebook information so let me check it out". The bookmarklet is simple enough, but it calls another javascript function which at the time (but not anymore) was highly compressed and undecipherable. That's when I said "nope, not gonna do it". So even though I could have verified the original uncompressed javascript from the Github site and even saved a local copy to verify and then run without hitting their server, I wasn't going to. It's several thousand lines and I'm not a total javascript guru to begin with. Yet, folks are using it anyway. Even (supposedly) bright developers. What makes them trust the script? Did they all scrutinize it line by line? Do they know the guy personally and trust him not to do anything bad? Do they just take his word? What makes you trust that a piece of open source software is not malicious?

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