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• Strange Recurrent Excessive I/O Wait

  - by Chris

  I know quite well that I/O wait has been discussed multiple times on this site, but all the other topics seem to cover constant I/O latency, while the I/O problem we need to solve on our server occurs at irregular (short) intervals, but is ever-present with massive spikes of up to 20k ms a-wait and service times of 2 seconds. The disk affected is /dev/sdb (Seagate Barracuda, for details see below). A typical iostat -x output would at times look like this, which is an extreme sample but by no means rare: iostat (Oct 6, 2013) tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await svctm %util 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16.00 0.00 156.00 9.75 21.89 288.12 36.00 57.60 5.50 0.00 44.00 8.00 48.79 2194.18 181.82 100.00 2.00 0.00 16.00 8.00 46.49 3397.00 500.00 100.00 4.50 0.00 40.00 8.89 43.73 5581.78 222.22 100.00 14.50 0.00 148.00 10.21 13.76 5909.24 68.97 100.00 1.50 0.00 12.00 8.00 8.57 7150.67 666.67 100.00 0.50 0.00 4.00 8.00 6.31 10168.00 2000.00 100.00 2.00 0.00 16.00 8.00 5.27 11001.00 500.00 100.00 0.50 0.00 4.00 8.00 2.96 17080.00 2000.00 100.00 34.00 0.00 1324.00 9.88 1.32 137.84 4.45 59.60 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 22.00 44.00 204.00 11.27 0.01 0.27 0.27 0.60 Let me provide you with some more information regarding the hardware. It's a Dell 1950 III box with Debian as OS where uname -a reports the following: Linux xx 2.6.32-5-amd64 #1 SMP Fri Feb 15 15:39:52 UTC 2013 x86_64 GNU/Linux The machine is a dedicated server that hosts an online game without any databases or I/O heavy applications running. The core application consumes about 0.8 of the 8 GBytes RAM, and the average CPU load is relatively low. The game itself, however, reacts rather sensitive towards I/O latency and thus our players experience massive ingame lag, which we would like to address as soon as possible. iostat: avg-cpu: %user %nice %system %iowait %steal %idle 1.77 0.01 1.05 1.59 0.00 95.58 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdb 13.16 25.42 135.12 504701011 2682640656 sda 1.52 0.74 20.63 14644533 409684488 Uptime is: 19:26:26 up 229 days, 17:26, 4 users, load average: 0.36, 0.37, 0.32 Harddisk controller: 01:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 (rev 04) Harddisks: Array 1, RAID-1, 2x Seagate Cheetah 15K.5 73 GB SAS Array 2, RAID-1, 2x Seagate ST3500620SS Barracuda ES.2 500GB 16MB 7200RPM SAS Partition information from df: Filesystem 1K-blocks Used Available Use% Mounted on /dev/sdb1 480191156 30715200 425083668 7% /home /dev/sda2 7692908 437436 6864692 6% / /dev/sda5 15377820 1398916 13197748 10% /usr /dev/sda6 39159724 19158340 18012140 52% /var Some more data samples generated with iostat -dx sdb 1 (Oct 11, 2013) Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sdb 0.00 15.00 0.00 70.00 0.00 656.00 9.37 4.50 1.83 4.80 33.60 sdb 0.00 0.00 0.00 2.00 0.00 16.00 8.00 12.00 836.00 500.00 100.00 sdb 0.00 0.00 0.00 3.00 0.00 32.00 10.67 9.96 1990.67 333.33 100.00 sdb 0.00 0.00 0.00 4.00 0.00 40.00 10.00 6.96 3075.00 250.00 100.00 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.00 0.00 0.00 100.00 sdb 0.00 0.00 0.00 2.00 0.00 16.00 8.00 2.62 4648.00 500.00 100.00 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.00 0.00 0.00 100.00 sdb 0.00 0.00 0.00 1.00 0.00 16.00 16.00 1.69 7024.00 1000.00 100.00 sdb 0.00 74.00 0.00 124.00 0.00 1584.00 12.77 1.09 67.94 6.94 86.00 Characteristic charts generated with rrdtool can be found here: iostat plot 1, 24 min interval: http://imageshack.us/photo/my-images/600/yqm3.png/ iostat plot 2, 120 min interval: http://imageshack.us/photo/my-images/407/griw.png/ As we have a rather large cache of 5.5 GBytes, we thought it might be a good idea to test if the I/O wait spikes would perhaps be caused by cache miss events. Therefore, we did a sync and then this to flush the cache and buffers: echo 3 > /proc/sys/vm/drop_caches and directly afterwards the I/O wait and service times virtually went through the roof, and everything on the machine felt like slow motion. During the next few hours the latency recovered and everything was as before - small to medium lags in short, unpredictable intervals. Now my question is: does anybody have any idea what might cause this annoying behaviour? Is it the first indication of the disk array or the raid controller dying, or something that can be easily mended by rebooting? (At the moment we're very reluctant to do this, however, because we're afraid that the disks might not come back up again.) Any help is greatly appreciated. Thanks in advance, Chris. Edited to add: we do see one or two processes go to 'D' state in top, one of which seems to be kjournald rather frequently. If I'm not mistaken, however, this does not indicate the processes causing the latency, but rather those affected by it - correct me if I'm wrong. Does the information about uninterruptibly sleeping processes help us in any way to address the problem? @Andy Shinn requested smartctl data, here it is: smartctl -a -d megaraid,2 /dev/sdb yields: smartctl 5.40 2010-07-12 r3124 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Device: SEAGATE ST3500620SS Version: MS05 Serial number: Device type: disk Transport protocol: SAS Local Time is: Mon Oct 14 20:37:13 2013 CEST Device supports SMART and is Enabled Temperature Warning Disabled or Not Supported SMART Health Status: OK Current Drive Temperature: 20 C Drive Trip Temperature: 68 C Elements in grown defect list: 0 Vendor (Seagate) cache information Blocks sent to initiator = 1236631092 Blocks received from initiator = 1097862364 Blocks read from cache and sent to initiator = 1383620256 Number of read and write commands whose size <= segment size = 531295338 Number of read and write commands whose size > segment size = 51986460 Vendor (Seagate/Hitachi) factory information number of hours powered up = 36556.93 number of minutes until next internal SMART test = 32 Error counter log: Errors Corrected by Total Correction Gigabytes Total ECC rereads/ errors algorithm processed uncorrected fast | delayed rewrites corrected invocations [10^9 bytes] errors read: 509271032 47 0 509271079 509271079 20981.423 0 write: 0 0 0 0 0 5022.039 0 verify: 1870931090 196 0 1870931286 1870931286 100558.708 0 Non-medium error count: 0 SMART Self-test log Num Test Status segment LifeTime LBA_first_err [SK ASC ASQ] Description number (hours) # 1 Background short Completed 16 36538 - [- - -] # 2 Background short Completed 16 36514 - [- - -] # 3 Background short Completed 16 36490 - [- - -] # 4 Background short Completed 16 36466 - [- - -] # 5 Background short Completed 16 36442 - [- - -] # 6 Background long Completed 16 36420 - [- - -] # 7 Background short Completed 16 36394 - [- - -] # 8 Background short Completed 16 36370 - [- - -] # 9 Background long Completed 16 36364 - [- - -] #10 Background short Completed 16 36361 - [- - -] #11 Background long Completed 16 2 - [- - -] #12 Background short Completed 16 0 - [- - -] Long (extended) Self Test duration: 6798 seconds [113.3 minutes] smartctl -a -d megaraid,3 /dev/sdb yields: smartctl 5.40 2010-07-12 r3124 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Device: SEAGATE ST3500620SS Version: MS05 Serial number: Device type: disk Transport protocol: SAS Local Time is: Mon Oct 14 20:37:26 2013 CEST Device supports SMART and is Enabled Temperature Warning Disabled or Not Supported SMART Health Status: OK Current Drive Temperature: 19 C Drive Trip Temperature: 68 C Elements in grown defect list: 0 Vendor (Seagate) cache information Blocks sent to initiator = 288745640 Blocks received from initiator = 1097848399 Blocks read from cache and sent to initiator = 1304149705 Number of read and write commands whose size <= segment size = 527414694 Number of read and write commands whose size > segment size = 51986460 Vendor (Seagate/Hitachi) factory information number of hours powered up = 36596.83 number of minutes until next internal SMART test = 28 Error counter log: Errors Corrected by Total Correction Gigabytes Total ECC rereads/ errors algorithm processed uncorrected fast | delayed rewrites corrected invocations [10^9 bytes] errors read: 610862490 44 0 610862534 610862534 20470.133 0 write: 0 0 0 0 0 5022.480 0 verify: 2861227413 203 0 2861227616 2861227616 100872.443 0 Non-medium error count: 1 SMART Self-test log Num Test Status segment LifeTime LBA_first_err [SK ASC ASQ] Description number (hours) # 1 Background short Completed 16 36580 - [- - -] # 2 Background short Completed 16 36556 - [- - -] # 3 Background short Completed 16 36532 - [- - -] # 4 Background short Completed 16 36508 - [- - -] # 5 Background short Completed 16 36484 - [- - -] # 6 Background long Completed 16 36462 - [- - -] # 7 Background short Completed 16 36436 - [- - -] # 8 Background short Completed 16 36412 - [- - -] # 9 Background long Completed 16 36404 - [- - -] #10 Background short Completed 16 36401 - [- - -] #11 Background long Completed 16 2 - [- - -] #12 Background short Completed 16 0 - [- - -] Long (extended) Self Test duration: 6798 seconds [113.3 minutes]

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• How can I unit test a class which requires a web service call?

  - by Chris Cooper

  I'm trying to test a class which calls some Hadoop web services. The code is pretty much of the form: method() { ...use Jersey client to create WebResource... ...make request... ...do something with response... } e.g. there is a create directory method, a create folder method etc. Given that the code is dealing with an external web service that I don't have control over, how can I unit test this? I could try and mock the web service client/responses but that breaks the guideline I've seen a lot recently: "Don't mock objects you don't own". I could set up a dummy web service implementation - would that still constitute a "unit test" or would it then be an integration test? Is it just not possible to unit test at this low a level - how would a TDD practitioner go about this?

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• Weblogs.asp.net has a problem, it is spam

  - by Chris Hammond

  Is anyone at Microsoft listening to the SPAM problem here on Weblogs.asp.net? My “ Can anyone do anything about the spam here on weblogs.asp.net? ” post from October got over 12 spam comments posted to it in the past 24 hours. I have comments all moderated, but that just means I have a crapload of work to do each time people comment. Also, when you click on a link from a comment notification email you are taken to an insecure site warning due to an invalid SSL Cert. We really just need some updates...(read more)

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• Agile Testing Days 2012 – Day 2 – Learn through disagreement

  - by Chris George

  I think I was in the right place! During Day 1 I kept on reading tweets about Lean Coffee that has happened earlier that morning. It intrigued me and I figured in for a penny in for a pound, and set my alarm for 6:45am. Following the award night the night before, it was _really_ hard getting up when it went off, but I did and after a very early breakfast, set off for the 10 min walk to the Dorint. With Lean Coffee due to start at 07:30, I arrived at the hotel and made my way to one of the hotel bars. I soon realised I was in the right place as although the bar was empty, there was a table with post-it’s and pens! This MUST be the place! The premise of Lean Coffee is to have several small timeboxed discussions. Everyone writes down what they would like to discuss on post-its that are then briefly explained and submitted to the pile. Once everyone is done, the group dot-votes on the topics. The topics are then sorted by the dot vote counts and the discussions begin. Each discussion had 8 mins to start with, which meant it prevented the discussions getting off topic too much. After the time elapsed, the group had a vote whether to extend the discussion by a further 4 mins or move on. Several discussion were had around training, soft skills etc. The conversations were really interesting and there were quite a few good ideas. Overall it was a very enjoyable experience, certainly worth the early start! Make Melly Happy Following Lean Coffee was real coffee, and much needed that was! The first keynote of the day was “Let’s help Melly (Changing Work into Life)”by Jurgen Appelo. Draw lines to track happiness This was a very interesting presentation, and set the day nicely. The theme to the keynote was projects are about the people, more-so than the actual tasks. So he started by showing a photo of an employee ‘Melly’ who looked happy enough. He then stated that she looked happy but actually hated her job. In fact 50% of Americans hate their jobs. He went on to say that the world over 50% of people hate Americans their jobs. Jurgen talked about many ways to reduce the feedback cycle, not only of the project, but of the people management. Ideas such as Happiness doors, happiness tracking (drawing lines on a wall indicating your happiness for that day), kudo boxes (to compliment a colleague for good work). All of these (and more) ideas stimulate conversation amongst the team, lead to early detection of issues and investigation of solutions. I’ve massively simplified Jurgen’s keynote and have certainly not done it justice, so I will post a link to the video once it’s available. Following more coffee, the next talk was “How releasing faster changes testing” by Alexander Schwartz. This is a topic very close to our hearts at the moment, so I was eager to find out any juicy morsels that could help us achieve more frequent releases, and Alex did not disappoint. He started off by confirming something that I have been a firm believer in for a number of years now; adding more people can do more harm than good when trying to release. This is for a number of reasons, but just adding new people to a team at such a critical time can be more of a drain on resources than they add. The alternative is to have the whole team have shared responsibility for faster delivery. So the whole team is responsible for quality and testing. Obviously you will have the test engineers on the project who have the specialist skills, but there is no reason that the entire team cannot do exploratory testing on the product. This links nicely with the Developer Exploratory testing presented by Sigge on Day 1, and certainly something that my team are really striving towards. Focus on cycle time, so what can be done to reduce the time between dev cycles, release cycles. What’s stops a release, what delays a release? all good solid questions that can be answered. Alex suggested that perhaps the product doesn’t need to be fully tested. Doing less testing will reduce the cycle time therefore get the release out faster. He suggested a risk-based approach to planning what testing needs to happen. Reducing testing could have an impact on revenue if it causes harm to customers, so test the ‘right stuff’! Determine a set of tests that are ‘face saving’ or ‘smoke’ tests. These tests cover the core functionality of the product and aim to prevent major embarrassment if these areas were to fail! Amongst many other very good points, Alex suggested that a good approach would be to release after every new feature is added. So do a bit of work -> release, do some more work -> release. By releasing small increments of work, the impact on the customer of bugs being introduced is reduced. Red Pill, Blue Pill The second keynote of the day was “Adaptation and improvisation – but your weakness is not your technique” by Markus Gartner and proved to be another very good presentation. It started off quoting lines from the Matrix which relate to adapting, improvising, realisation and mastery. It has alot of nerds in the room smiling! Markus went on to explain how through deliberate practice ( and a lot of it!) you can achieve mastery, but then you never stop learning. Through methods such as code retreats, testing dojos, workshops you can continually improve and learn. The code retreat idea was one that interested me. It involved pairing to write an automated test for, say, 45 mins, they deleting all the code, finding a different partner and writing the same test again! This is another keynote where the video will speak louder than anything I can write here! Markus did elaborate on something that Lisa and Janet had touched on yesterday whilst busting the myth that “Testers Must Code”. Whilst it is true that to be a tester, you don’t need to code, it is becoming more common that there is this crossover happening where more testers are coding and more programmers are testing. Markus made a special distinction between programmers and developers as testers develop tests code so this helped to make that clear. “Extending Continuous Integration and TDD with Continuous Testing” by Jason Ayers was my next talk after lunch. We already do CI and a bit of TDD on my project team so I was interested to see what this continuous testing thing was all about and whether it would actually work for us. At the start of the presentation I was of the opinion that it just would not work for us because our tests are too slow, and that would be the case for many people. Jason started off by setting the scene and saying that those doing TDD spend between 10-15% of their time waiting for tests to run. This can be reduced by testing less often, reducing the test time but this then increases the risk of introduced bugs not being spotted quickly. Therefore, in comes Continuous Testing (CT). CT systems run your unit tests whenever you save some code and runs them in the background so you can continue working. This is a really nice idea, but to do this, your tests must be fast, independent and reliable. The latter two should be the case anyway, and the first is ideal, but hard! Jason makes several suggestions to make tests fast. Firstly keep the scope of the test small, secondly spin off any expensive tests into a suite which is run, perhaps, overnight or outside of the CT system at any rate. So this started to change my mind, perhaps we could re-engineer our tests, and continuously run the quick ones to give an element of coverage. This talk was very interesting and I’ve already tried a couple of the tools mentioned on our product (Mighty Moose and NCrunch). Sadly due to the way our solution is built, it currently doesn’t work, but we will look at whether we can make this work because this has the potential to be a mini-game-changer for us. Using the wrong data Gojko’s Hierarchy of Quality The final keynote of the day was “Reinventing software quality” by Gojko Adzic. He opened the talk with the statement “We’ve got quality wrong because we are using the wrong data”! Gojko then went on to explain that we should judge a bug by whether the customer cares about it, not by whether we think it’s important. Why spend time fixing issues that the customer just wouldn’t care about and releasing months later because of this? Surely it’s better to release now and get customer feedback? This was another reference to the idea of how it’s better to build the right thing wrong than the wrong thing right. Get feedback early to make sure you’re making the right thing. Gojko then showed something which was very analogous to Maslow’s heirachy of needs. Successful – does it contribute to the business? Useful – does it do what the user wants Usable – does it do what it’s supposed to without breaking Performant/Secure – is it secure/is the performance acceptable Deployable Functionally ok – can it be deployed without breaking? He then explained that User Stories should focus on change. In other words they should focus on the users needs, not the users process. Describe what the change will be, how that change will happen then measure it! Networking and Beer Following the day’s closing keynote, there were drinks and nibble for the ‘Networking’ evening. This was a great opportunity to talk to people. I find approaching strangers very uncomfortable but once again, when in Rome! Pete Walen and I had a long conversation about only fixing issues that the customer cares about versus fixing issues that make you proud of your software! Without saying much, and asking the right questions, Pete made me re-evaluate my thoughts on the matter. Clever, very clever!  Oh and he ‘bought’ me a beer! My Takeaway Triple from Day 2: release small and release often to minimize issues creeping in and get faster feedback from ‘the real world’ Focus on issues that the customers care about, not what we think is important It’s okay to disagree with someone, even if they are well respected agile testing gurus, that’s how discussion and learning happens!  

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• How to Build Services from Legacy Applications

  - by Chris Falter

  The SOA consultants invaded the executive suite at your company or agency, preached the true religion, and converted the unbelievers. Now by divine imperative you must convert your legacy applications into a suite of reusable services.  But as usual, you lack the time and resources that you need in order to develop the services properly.  So you googled or bing’ed, found this blog post, and began crying in gratitude.  Yes, as the title implies, I am going to reveal my easy, 3-step, works-every-time process for converting silos of legacy applications into the inventory of services your CIO has been dreaming about.  So just close your eyes and count to 3 … now open them … and here it is…. Not. While wishful thinking is too often the coin of the IT realm, even the most naive practitioner knows that converting legacy applications into reusable services requires more than a magic wand.  The reason is simple: if your starting point is your legacy applications, then you will simply be bolting a web service technology layer on top of your legacy API.  And that legacy API is built in the image of the silo applications.  Enter the wide gate of the legacy API, follow the broad path of generating service interfaces from existing code, and you will arrive at the siloed enterprise destruction that you thought you were escaping. The Straight and Narrow Path This past week I had the opportunity to learn how the FBI Criminal Justice Information Systems department has been transitioning from silo applications to a service inventory.  Lafe Hutcheson, IT Specialist in the architecture group and fellow attendee at an SOA Architect Certification Workshop, was my guide.  Lafe has survived the chaos of an SOA initiative, so it is not surprising that he was able to return from a US Army deployment to Kabul, Afghanistan with nary a scratch.  According to Lafe, building their service inventory is a three-phase process: Model a business process.  This requires intense collaboration between the IT and business wings of the organization, of course.  The FBI uses IBM Websphere tools to model the process with BPMN. Identify candidate services to facilitate the business process. Convert the BPMN to an executable BPEL orchestration, model and develop the services, and use a BPEL engine to run the process.  The FBI uses ActiveVOS for orchestration services. The 12 Step Program to End Your Legacy API Addiction Thomas Erl has documented a process for building a web service inventory that is quite similar to the FBI process. Erl’s process adds a technology architecture definition phase, which allows for the technology environment to influence the inventory blueprint.  For example, if you are using an enterprise service bus, you will probably not need to build your own utility services for logging or intermediate routing.  Erl also lists a service-oriented analysis phase that highlights the 12-step process of applying the principles of service orientation to modeling your services.  Erl depicts the modeling of a service inventory as an iterative process: model a business process, define the relevant technology architecture, define the service inventory blueprint, analyze the services, then model another business process, rinse and repeat.  (Astute readers will note that Erl’s diagram, restricted to analysis and modeling process, does not include the implementation phase that concludes the FBI service development methodology.) The service-oriented analysis phase is where you find the 12 steps that will free you from your legacy API addiction. In a nutshell, you identify the steps in the process that need services; identify the different types of services (agnostic entity services, service compositions, and utility services) that are required; apply service-orientation principles; and normalize the inventory into cohesive service models. Rather than discuss each of the 12 steps individually, I will close by simply referring my readers to Erl’s explanation.

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• Three apps going through apache. How to configure apache httpd? [migrated]

  - by Chris F.

  I have a quick question but I've been struggling to find the best solution: I have two java webapps and wordpress (php) that I need to serve through my Prod website: App #1 should be accessed when pointing to www.example.com/ (this would have other url too such as "www.example.com/book") App #2 should be accessed when pointing to www.example.com/manage Finally WordPress would be accessed at www.example.com/info How can I configure apache to serve all these three instances at the same time? So far I have and it's not quite working right. Any suggestions would be much appreciated! Listen 8081 <VirtualHost *:8081> DocumentRoot /var/www/html </VirtualHost> ProxyPass /manage http://127.0.0.1:8080/manage ProxyPassReverse /manage http://127.0.0.1:8080/manage ProxyPass /info http://127.0.0.1:8081/info ProxyPassReverse /info http://127.0.0.1:8081/info ProxyPass / http://127.0.0.1:9000/ ProxyPassReverse / http://127.0.0.1:9000/

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• Stored procedure Naming conventions?

  - by Chris

  One of our senior developers has stated that we should be using a naming convention for stored procedures with an "objectVerb" style of naming such as ("MemberGetById") instead of a "verbObject" type of naming ("GetMemberByID"). The reasoning for this standard is that all related stored procedures would be grouped together by object rather than by the action. While I see the logic for this way of naming things, this is the first time that I have seen stored procedures named this way. My opinion of the naming convention is that the name can not be read naturally and takes some time to determine what the words are saying and what the procedure might do. What are your takes on this? Which way is the more common way of naming a stored proc, and does a what types of stored proc naming conventions have you used or go by?

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• How to create per-vertex normals when reusing vertex data?

  - by Chris Smith

  I am displaying a cube using a vertex buffer object (gl.ELEMENT_ARRAY_BUFFER). This allows me to specify vertex indicies, rather than having duplicate vertexes. In the case of displaying a simple cube, this means I only need to have eight vertices total. Opposed to needing three vertices per triangle, times two triangles per face, times six faces. Sound correct so far? My question is, how do I now deal with vertex attribute data such as color, texture coordinates, and normals when reusing vertices using the vertex buffer object? If I am reusing the same vertex data in my indexed vertex buffer, how can I differentiate when vertex X is used as part of the cube's front face versus the cube's left face? In both cases I would like the surface normal and texture coordinates to be different. I understand I could average the surface normal, however I would like to render a cube. Also, this still doesn't work for texture coordinates. Is there a way to save memory using a vertex buffer object while being able to provide different vertex attribute data based on context? (Per-triangle would be idea.) Or should I just duplicate each vertex for each context in which it gets rendered. (So there is a one-to-one mapping between vertex, normal, color, etc.) Note: I'm using OpenGL ES.

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• How to price code reviews to encourage good behavior?

  - by Chris Clark

  I work for a company that has a hosted .net internet application with many clients. Those clients often want to write customizations for our application. We have APIs to hook into the app, but the customizations themselves are written in .net. This is a shared, secure hosting environment and we have to code review these customizations before we can deploy them in our datacenter to ensure that they don't degrade performance, crash our servers, or open any security vulnerabilities. We charge for these code reviews. The current pricing model is simply a function of the number of lines of code. I think this is a bad idea for a variety of reasons, but primarily because, if we are interested in verifying that the code works as expected, we should be incentivizing good, readable code, not compaction. I would like to propose a pricing model that incorporates some, or all of the following as inputs: Lines of code Cyclomatic complexity Avg function length # of functions Are there any other metrics I should incorporate, or other ideas for how we can reasonably create pricing for code reviews that encourages safe and understandable code?

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• Immutable Method in Java

  - by Chris Okyen

  In Java, there is the final keyword in lieu of the const keyword in C and C++. In the latter languages there are mutable and immutable methods such as stated in the answer by Johannes Schaub - litb to the question How many and which are the uses of “const” in C++? Use const to tell others methods won't change the logical state of this object. struct SmartPtr { int getCopies() const { return mCopiesMade; } }ptr1; ... int var = ptr.getCopies(); // returns mCopiesMade and is specified that to not modify objects state. How is this performed in Java?

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• I have neither grub.conf nur menu.lst

  - by chris

  Hi, I just compiled my own kernel for the first time. At it is written in a tutorial I now want to check whether the kernel got written into the grub.conf file. Well, I did not find a grub.conf file. So I googled. Answer: Ubuntu does not have grub.conf, but rather has a menu.lst (also stored in /boot/grub). So I looked for that file. But I don't have that one either. So now the question: Where is my GRUB data stored? Im using Ubuntu 10.10 with Kernel 2.6.35-27

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• What's the difference between MariaDB and MySQL?

  - by Chris J. Lee

  What's the difference between MariaDB and MySQL? I'm not very familiar with both. I'm primarily a front end developer for the most part. Are they syntactically similar? Where do these two query languages differ? Wikipedia only mentions the difference between licensing: MariaDB is a community-developed branch of the MySQL database, the impetus being the community maintenance of its free status under GPL, as opposed to any uncertainty of MySQL license status under its current ownership by Oracle.

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• My Tech Ed North America Preview - Certification Edition

  - by Chris Gardner

  In my previous TechEd North America Preview, I addressed all the content I wanted to see at the show. This time, we shall turn our attention to the certifications I might try to pick up. If you have never been to TechEd North America before, one of the greatest things about the event is an on-site certification center. If you have a couple hours to spare, you can walk up to a test. The first test on my agenda is 70-5231. I took this update test once, but did not do well on the MVC portion2. A few practice tests later, and I think I'm ready to fake that section. After that, I need to complete my road to being a master. The good folks here at work have been having a real love / hate relationship with the idea of me become an MCM in SQL Server3. Of course, before I do that, I need to finally take the SQL Administration tests. Thus, we shall add 70-4324 and 70-4505 to the list. Speaking of MCM, TechEd North America will have a special on test 88-9706. This test is normally $500, and you have to find a place to take it7. However, there is a special 50% off rate for people who take it on location. With those kind of prices, I may just take it as a form of study guide. As a final push, I may take some Windows Phone exams. I mentioned in my previous post that I may attend the 70-5998 Exam Cram session. Unfortunately, I will be staffing the Hands-On-Lab at that time. As we know, this has never stopped me from taking a test. This may lead to fits of 70-5069, but after we've come this far... That should complete my list. Do I really think I'll find time to take 6 tests at TechEd North America? Probably not. I have done it at TechEd North America before, but that was before I was TechEd North America staff. I also had a co-worker pass 9 in one year, but he basically did nothing but travel to Orlando in 2007 to take tests. And what's the point of attending a HUGE conference if you don't network? Of course, networking will have to wait for Friday's post... 1 Upgrade: Transition Your MCPD .NET Framework 3.5 Web Developer Skills to MCPD .NET Framework 4 Web Developer 2Because I never have used, nor do I really think I ever will use, MVC... 3By that, I mean they love the idea, and they hate the price 4Microsoft SQL Server 2008, Implementation and Maintenance 5PRO: Designing, Optimizing and Maintaining a Database Administrative Solution Using Microsoft SQL Server 2008 6SQL Server 2008 Microsoft Certified Master: Knowledge Exam 7Which isn't nearly as expensive as the Lab Exam, nor as difficult to find a location. However, it is not offered at every testing facility. 8PRO: Designing and Developing Windows Phone Applications 9TS: Silverlight 4, Development

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• Most efficient arc for developing cross-browser support?

  - by Chris Hasbrouck

  I'm curious to hear what approach people take to planning for cross-browser support when developing a website. There are generally two approaches I've seen developers take in their workflow: -optimize for webkit then apply hacks for IE7-9, or -optimize for IE7-8 then apply newer features for IE9/webkit Basically starting at the front of technology and working toward the back, or starting at the back of technology and working toward the front. How do you do things? What advantages or disadvantage do you perceive in the different way of doing things wrt to developing cross-browser support?

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• How to stop fan running always on Asus P8P76LE motherboard with ATI Radeon HD6900

  - by Chris Good

  I'm using Ubuntu 12.04 LTS. I'm not sure if it is the CPU (i7) fan or the video card fan. I've tried using lm-sensors & fancontrol sudo sensors-detect Now follows a summary of the probes I have just done. Just press ENTER to continue: Driver `w83627ehf': * ISA bus, address 0x290 Chip `Nuvoton NCT6776F Super IO Sensors' (confidence: 9) Driver `coretemp': * Chip `Intel digital thermal sensor' (confidence: 9) To load everything that is needed, add this to /etc/modules: # Chip drivers coretemp w83627ehf Like many people, I'm also getting error: /usr/sbin/pwmconfig: There are no pwm-capable sensor modules installed Here is the output of sensors: # sensors radeon-pci-0100 Adapter: PCI adapter temp1: +71.0°C coretemp-isa-0000 Adapter: ISA adapter Physical id 0: +44.0°C (high = +80.0°C, crit = +98.0°C) Core 0: +44.0°C (high = +80.0°C, crit = +98.0°C) Core 1: +40.0°C (high = +80.0°C, crit = +98.0°C) Core 2: +43.0°C (high = +80.0°C, crit = +98.0°C) Core 3: +42.0°C (high = +80.0°C, crit = +98.0°C) I'm hoping some-one has already solved this for my configuration because this seems to be a problem for many people and there are many different suggestions.

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• libgdx intersection problem between rectangle and circle

  - by Chris

  My collision detection in libgdx is somehow buggy. player.png is 20*80px and ball.png 25*25px. Code: @Override public void create() { // ... batch = new SpriteBatch(); playerTex = new Texture(Gdx.files.internal("data/player.png")); ballTex = new Texture(Gdx.files.internal("data/ball.png")); player = new Rectangle(); player.width = 20; player.height = 80; player.x = Gdx.graphics.getWidth() - player.width - 10; player.y = 300; ball = new Circle(); ball.x = Gdx.graphics.getWidth() / 2; ball.y = Gdx.graphics.getHeight() / 2; ball.radius = ballTex.getWidth() / 2; } @Override public void render() { Gdx.gl.glClearColor(1, 1, 1, 1); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); camera.update(); // draw player, ball batch.setProjectionMatrix(camera.combined); batch.begin(); batch.draw(ballTex, ball.x, ball.y); batch.draw(playerTex, player.x, player.y); batch.end(); // update player position if(Gdx.input.isKeyPressed(Keys.DOWN)) player.y -= 250 * Gdx.graphics.getDeltaTime(); if(Gdx.input.isKeyPressed(Keys.UP)) player.y += 250 * Gdx.graphics.getDeltaTime(); if(Gdx.input.isKeyPressed(Keys.LEFT)) player.x -= 250 * Gdx.graphics.getDeltaTime(); if(Gdx.input.isKeyPressed(Keys.RIGHT)) player.x += 250 * Gdx.graphics.getDeltaTime(); // don't let the player leave the field if(player.y < 0) player.y = 0; if(player.y > 600 - 80) player.y = 600 - 80; // check collision if (Intersector.overlaps(ball, player)) Gdx.app.log("overlaps", "yes"); }

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• Different methods of ammo resupply

  - by Chris Mantle

  I'm writing a small game at the moment. Presently, I have one or two design elements that aren't locked down yet, and I wanted to ask for input on one of these. For dramatic effect, the player's character in my game is immobilised, alone and has a supposedly limited amount of ammo for their weapons. However, I would like to periodically resupply the player with ammo (for the purpose of balancing the level of difficulty and to allow the player to continue if they're doing well). I'm trying to think of a method of resupply that's different to the more familiar strategies of making ammo magically appear or having the antagonists drop some when they die. I'd like to emphasise the notion of the player's isolation as much as possible, and finding a way of 'sneaking' ammo to the player without removing too much of that emphasis is basically what I'm trying to think of (it's definitely a valid argument that resupplying the player removes it anyway) I have considered a sort of simple in-game 'store', where kills get you points that you can spend on ammo for your favourite weapon. This might work well, and may also be good for supporting a simple micro-transaction business model within the game. However, you'd have to pause the game often to make purchases, which would interrupt the action, and it works against the notion of isolation. Any thoughts?

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• Computing a normal matrix in conjunction with gluLookAt

  - by Chris Smith

  I have a hand-rolled camera class that converts yaw, pitch, and roll angles into a forward, side, and up vector suitable for calling gluLookAt. Using this camera class I can modify the model-view matrix to move about the 3D world just fine. However, I am having trouble when using this camera class (and associated model-view matrix) when trying to perform directional lighting in my vertex shader. The problem is that the light direction, (0, 1, 0) for example, is relative to where the 'camera is looking' and not the actual world coordinates. (Or is this eye coordinates vs. model coordinates?) I would like the light direction to be unaffected by the camera's viewing direction. For example, when the camera is looking down the Z axis the ground is lit correctly. However, if I point the camera straight at the ground, then it goes dark. This is (I think) because the light direction is parallel with the camera's 'up' vector which is perpendicular with the ground's normal vector. I tried computing the normal matrix without taking the camera's model view into account, but then none of my objects were rotated correctly. Sorry if this sounds vague. I suspect there is a straight forward answer, but I'm not 100% clear on how the normal matrix should be used for transforming vertex normals in my vertex shader. For reference, here is pseudo code for my rendering loop: pMatrix = new Matrix(); pMatrix = makePerspective(...) mvMatrix = new Matrix() camera.apply(mvMatrix); // Calls gluLookAt // Move the object into position. mvMatrix.translatev(position); mvMatrix.rotatef(rotation.x, 1, 0, 0); mvMatrix.rotatef(rotation.y, 0, 1, 0); mvMatrix.rotatef(rotation.z, 0, 0, 1); var nMatrix = new Matrix(); nMatrix.set(mvMatrix.get().getInverse().getTranspose()); // Set vertex shader uniforms. gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, new Float32Array(pMatrix.getFlattened())); gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, new Float32Array(mvMatrix.getFlattened())); gl.uniformMatrix4fv(shaderProgram.nMatrixUniform, false, new Float32Array(nMatrix.getFlattened())); // ... gl.drawElements(gl.TRIANGLES, this.vertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0); And the corresponding vertex shader: // Attributes attribute vec3 aVertexPosition; attribute vec4 aVertexColor; attribute vec3 aVertexNormal; // Uniforms uniform mat4 uMVMatrix; uniform mat4 uNMatrix; uniform mat4 uPMatrix; // Varyings varying vec4 vColor; // Constants const vec3 LIGHT_DIRECTION = vec3(0, 1, 0); // Opposite direction of photons. const vec4 AMBIENT_COLOR = vec4 (0.2, 0.2, 0.2, 1.0); float ComputeLighting() { vec4 transformedNormal = vec4(aVertexNormal.xyz, 1.0); transformedNormal = uNMatrix * transformedNormal; float base = dot(normalize(transformedNormal.xyz), normalize(LIGHT_DIRECTION)); return max(base, 0.0); } void main(void) { gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0); float lightWeight = ComputeLighting(); vColor = vec4(aVertexColor.xyz * lightWeight, 1.0) + AMBIENT_COLOR; } Note that I am using WebGL, so if the anser is use glFixThisProblem(...) any pointers on how to re-implement that on WebGL if missing would be appreciated.

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• bootable USB / installation requirements

  - by Chris Wilson

  Originally asked on One Hundred Paper Cuts Answers thread On the official site: http://www.ubuntu.com/netbook/get-ubuntu/download The instructions for creating a bootable USB key for installing Ubuntu Netbook Remix include a line saying: "Insert a USB stick with at least 2GB of free space" I recently installed UNR on a netbook -- in fact, the one I'm using right now -- and I went ahead despite only having a 1GB USB key on hand. Everything went smoothly and installed 100% correctly. If I had waited to go out and buy a 2GB USB key I would have spent that money unnecessarily and wouldn't have been able to use the computer in the meantime. I was wondering if there's a specific rationale for requiring a 2GB USB key, or if the instructions could be changed to indicate that it can be done with only 1GB. Thanks!

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• 3D Camera Problem

  - by Chris

  I allow the user to look around the scene by holding down the left mouse button and moving the mouse. The problem that I have is I can be facing one direction, I move the mouse up and the view tilts up, I move down and the view titles down. If I spin around 180 my left and right still works fine, but when I move the mouse up the view tilts down, and when I move the mouse down the view titles up. This is the code I am using, can anyone see what the problem with the logic is? var viewDir = g_math.subVector(target, g_eye); var rotatedViewDir = []; rotatedViewDir[0] = (Math.cos(g_mouseXDelta * g_rotationDelta) * viewDir[0]) - (Math.sin(g_mouseXDelta * g_rotationDelta) * viewDir[2]); rotatedViewDir[1] = viewDir[1]; rotatedViewDir[2] = (Math.cos(g_mouseXDelta * g_rotationDelta) * viewDir[2]) + (Math.sin(g_mouseXDelta * g_rotationDelta) * viewDir[0]); viewDir = rotatedViewDir; rotatedViewDir[0] = viewDir[0]; rotatedViewDir[1] = (Math.cos(g_mouseYDelta * g_rotationDelta * -1) * viewDir[1]) - (Math.sin(g_mouseYDelta * g_rotationDelta * -1) * viewDir[2]); rotatedViewDir[2] = (Math.cos(g_mouseYDelta * g_rotationDelta * -1) * viewDir[2]) + (Math.sin(g_mouseYDelta * g_rotationDelta * -1) * viewDir[1]); g_lookingDir = rotatedViewDir; var newtarget = g_math.addVector(rotatedViewDir, g_eye);

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• OpenGL ES Basic Fragment Shader help with transparency

  - by Chris

  I have just spent my first half hour playing with the shader language. I have modified the basic program I have which renders the texture, to allow me to colour the texture. varying vec2 texCoord; uniform sampler2D texSampler; /* Given the texture coordinates, our pixel shader grabs the corresponding * color from the texture. */ void main() { //gl_FragColor = texture2D(texSampler, texCoord); gl_FragColor = vec4(0,1,0,1)*vec4(texture2D(texSampler,texCoord).xyz,1); } I have noticed how this affects my transparent textures, and I believe I am loosing the alpha channel which would explain why previously transparent area's appear totally black. If I use the following line instead, I am shown the transparent area's gl_FragColor = vec4(0,1,0,1)*vec4(texture2D(texSampler,texCoord).aaa,1); How can I retain the transparency after this modification to the colour? I have seen various things about a .w property, and also luminous, but my tweaks with those and the .aaa property are not working XD

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• ASP.NET MVC WebService - Security for Industrial Android Clients

  - by Chris Nevill

  I'm trying to design a system that will allow a bunch of Android devices to securely log into an ASP.NET MVC REST Web service. At present neither side are implemented. However there is an ASP.NET MVC website which the web service will site along side. This is currently using forms authentication. The idea will be that the Android devices will download data from the web service and then be able to work offline storing data in their own local databases, where users will be able to make updates to that data, and then syncing updates back to the main server where possible. The web service will be using HTTPS to prevent calls being intercepted and reduce the risk of calls being intercepted. The system is an industrial system and will not be in used by the general Android population. Instead only authorized Android devices will be authorized by the Web Service to make calls. As such I was thinking of using the Android devices serial number as a username and then a generated long password which the device will be able to pick up - once the device has been authorized server side. The device will also have user logins - but these will not be to log into the web service - just the device itself - since the device and user must be able to work offline. So usernames and passwords will be downloaded and stored on the devices themselves. My question is... what form of security is best setup on the web service? Should it use forms Authentication? Should the username and password just be passed in with each GET/POST call or should it start a session as I have with the website? The Android side causes more confusion. There seems to be a number of options here Spring-Android, Volley, Retrofit, LoopJ, Robo Spice which seems to use the aforementioned Spring, Retrofit or Google HttpClient. I'm struggling to find a simple example which authenticates with a forms based authentication system. Is this because I'm going about this wrong? Is there another option that would better suite this?

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• Best SEO practices for mobile URLs: 301, rel=canonical, or something else?

  - by Chris

  I am developing a site with a mobile version and am trying to figure the appropriate way to manage the URLs for search engines. So far I've considered: Having a separate mobile site (m.example.com) with rel="canonical" links to the regular site. Putting both the mobile site and full site on one URL (example.com), and doing user agent sniffing. Another opinion: Spencer: "If you have a mobile site at a separate location or URL, you should 301 redirect each and every mobile page to its corresponding page on your main website. Employ user agent detection so that the mobile optimized version is served up if someone's coming in from a hand-held. - http://developer.practicalecommerce.com/articles/1722-Mobile-site-Development-Best-Practices-for-SEO-Usability Both 2 and 3 make it hard for a user who wants to switch to the full site or mobile site manually, but I'm not sure 1 is the best alternative. What's the best way to write URLs for a mobile site?

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• Recommendations for adjustable sit-stand workstations?

  - by Chris Phillips

  Recently, I've been feeling the discomfort of sitting at my desk all day long. I'm fairly active, stretch, and take regular breaks, but some days it's still pretty uncomfortable to sit all day long, whether in a nice chair or on an exercise ball. I would really like able to stand at my computer for part of the day. My current setup is a large desk with two 26" lcds and a 17" laptop. I don't mind if the laptop isn't adjustable, as I don't use it as regularly as the monitors. I would like to be able to fairly easily switch from a sitting position to a standing position and back again as necessary. I've been looking into adjustable height desks and stands and found that they tend to be either really expensive, or don't quite meet my needs. (For example, the Ergotron WorkFit-S Dual LCD workstation looks like the ideal feature set at a reasonable price, but won't fit with my monitors.) Any suggestions or thoughts? Update: fixed a typo. Thanks @RDL!

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• Fight for your rights as a video gamer.

  - by Chris Williams

  Soon, the U.S. Supreme Court may decide whether to hear a case that could have a lasting impact on computer and video games. The case before the Court involves a law passed by the state of California attempting to criminalize the sale of certain computer and video games. Two previous courts rejected the California law as unconstitutional, but soon the Supreme Court could have the final say. Whatever the Court's ruling, we must be prepared to continue defending our rights now and in the future. To do so, we need a large, powerful movement of gamers to speak with one voice and show that we won't sit back while lawmakers try to score political points by scapegoating video games and treating them differently than books, movies, and music. If the Court decides to hear the case, we're going to need thousands of activists like you who can help defend computer and video games by writing letters to editors, calling into talk radio stations, and educating Americans about our passion for and appreciation of computer and video games. You can help build this movement right now by inviting all your friends and fellow gamers to join the Video Game Voters Network. Use our simple tool to send an email to everyone you know asking them to stand up for gaming rights: http://videogamevoters.org/movement You can also help spread the word through Facebook and Twitter, or you can simply forward this email to everyone you know and ask them to sign up at videogamevoters.org. Time after time, courts continue to reject politicians' efforts to restrict the sale of computer and video games. But that doesn't mean the politicians will stop trying anytime soon -- in fact, it means they're likely to ramp up their efforts even more. To stop them, we must make it clear that gamers will continue to stand up for free speech -- and that the numbers are on our side. Help make sure we're ready and able to keep fighting for our gaming rights. Spread the word about the Video Game Voters Network right now: http://videogamevoters.org/movement Thank you. -- Video Game Voters Network

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