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• Java Spotlight Episode 98: Cliff Click on Benchmarkings

  - by Roger Brinkley

  Interview with Cliff Click of 0xdata on benchmarking. Recorded live at JFokus 2012. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News Bean Validation 1.1 Java EE 7 Roadmap Java JRE Update 7u7 and 6u35 available. Change to Java SE 7 and Java SE 6 Update Release Numbers JCP 2012 Award Nominations Announced Griffon JavaFX Plugin Events Sep 3-6, Herbstcampus, Nuremberg, Germany Sep 10-15, IMTS 2012 Conference,  Chicago Sep 12,  The Coming M2M Revolution: Critical Issues for End-to-End Software and Systems Development,  Webinar Sep 30-Oct 4, JavaONE, San Francisco Oct 3-4, Java Embedded @ JavaONE, San Francisco Oct 15-17, JAX London Oct 30-Nov 1, Arm TechCon, Santa Clara Oct 22-23, Freescale Technology Forum - Japan, Tokyo Nov 2-3, JMagreb, Morocco Nov 13-17, Devoxx, Belgium Feature Interview Cliff Click is the CTO and Co-Founder of 0xdata, a firm dedicated to creating a new way to think about web-scale data storage and real-time analytics. I wrote my first compiler when I was 15 (Pascal to TRS Z-80!), although my most famous compiler is the HotSpot Server Compiler (the Sea of Nodes IR). I helped Azul Systems build an 864 core pure-Java mainframe that keeps GC pauses on 500Gb heaps to under 10ms, and worked on all aspects of that JVM. Before that I worked on HotSpot at Sun Microsystems, and am at least partially responsible for bringing Java into the mainstream. I am invited to speak regularly at industry and academic conferences and has published many papers about HotSpot technology. I hold a PhD in Computer Science from Rice University and about 15 patents. What’s Cool Shaun Smith’s Devoxx 2011 talk "JPA Multi-Tenancy & Extensibility" now freely available at Parleys.

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• How to become a "faster" programmer?

  - by Nick Gotch

  My last job evaluation included just one weak point: timeliness. I'm already aware of some things I can do to improve this but what I'm looking for are some more. Does anyone have tips or advice on what they do to increase the speed of their output without sacrificing its quality? How do you estimate timelines and stick to them? What do you do to get more done in shorter time periods? Any feedback is greatly appreciated, thanks,

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• Current trends in Random Access Memory

  - by Nutel

  As I know for now because of laws of Physics there will be not any tangible improvements in CPU cycles per second for the nearest future. However because of Von Neumann bottleneck it seems to not be an issue for non-server applications. So what about RAM, is there any upcoming technologies that promise to improve memory speed or we are stack with the current situation till quantum computers will come out from labs?

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• What is the best way to keep track of the median?

  - by Steven Mou

  I read a question in one book: Numbers are randomly generated and stored into an (expanding) array, How would you keep track of the median? There are two data structures can solve the problem. One is the balanced binary tree, the other is two heaps which keep trace of the biggest half and the smallest half of the elements. I think these two solutions has the same running time as O(n lg n), but I am not sure of my judgement. In your opinions, What is the best way to keep track of the median?

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• Cat 6 Only 100mbit speed

  - by Stu2000

  I tried two different cat6 cables directly connected between my two ubuntu machines. This one I ordered online: http://www.amazon.co.uk/gp/product/B002SQPDXS/ref=wms_ohs_product only achieves 100mbit speeds, but does appear to be supporting cross-talk (direct pc to pc), the other cat 6 cable, worked perfectly and gets the full 1gigabit speed. Both tests were performed using ftp and checking the network monitor with direct pc to pc connection. Did the product from amazon lie to me or do I need to manually set a setting somewhere in ubuntu for some cables? I had thought 10 quid for 20m of gigabit ethernet cable was a bit cheap, you get what you pay for... Regards, Stu Update: It seems that after rebooting, the device is set to 1000mbit sec when looking it up with sudo ethtool eth0 However after a while, this will drop down to just 100, after which to reset it to 1000 again, I have to reboot, and simply unpugging and re-plugging in the cable doesn't do it. I tried setting this in networking config file as suggested here: auto eth0 iface eth0 inet static pre-up /usr/sbin/ethtool -s eth0 speed 1000 duplex full but that resulted in my networking failing to start. Is there a problem with my 'auto-negotiation' or something? Can I manually override a setting to 1000mbit?

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• OpenGL profiling with AMD PerfStudio 2

  - by Aurus

  I'm rendering just a really small amount of polygons for my UI but however I still tried to increase the FPS. In the end I removed redundant calls which increased the FPS. I really don't want to lose FPS for nothing so I keep looking for more improvements. The first thing I noticed is the "huge" time where no calls are made before SwapBuffer (the black one). Well I know that OpenGL works asynchronous so SwapBuffer has to wait until everything is done. But shouldn't PerfStudio mark this time also as black ? Correct me If I am wrong. The second thing I noticed is that some glUniform2f calls just take longer (the brown ones). I mean they should all upload 2floats to the GPU how can the time be so different from call to call. The program isn't even changed or something like that. I also tried to look at other programs like gDebugger or CodeXL but they often crashed and they show less statistics (only # of calls or redundant calls etc.) EDIT: I also realized that the draw calls also have different durations, which was obvious for me but sometimes drawing more vertices is faster than drawing less vertices.

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• Regulating how much to draw based on how much was drawn last frame.

  - by Mike Howard

  I have a 3D game world on an iPhone (limited graphics speed), and I'm already regulating whether I draw each shape on the screen based on it's size and distance from the camera. Something like... if (how_big_it_looks_from_the_camera > constant) then draw What I want to do now is also take into account how many shapes are being drawn, so that in busier areas of the game world I can draw less than I otherwise would. I tried to do this by dividing how_big_it_looks by the number of shapes that were drawn last frame (well, the square root of this but I'm simplifying - the problem is the same). if (how_big_it_looks / shapes_drawn > constant2) then draw But the check happens at the level of objects which represent many drawn shapes, and if an object containing many shapes is switched on, it increases shapes_drawn lots and switches itself back off the next frame. It flickers on and off. I tried keeping a kind of weighted average of previous values, by each frame doing something like shapes_drawn_recently = 0.9 * shapes_drawn_recently + 0.1 * shapes_just_drawn, but of course it only slows the flickering down because of the nature of the feedback loop. Is there a good way of solving this? My project is in Objective-C, but a general algorithm or pseudo-code is good too. Thanks.

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• Spatial data from shapefiles (for T-SQL Tuesday #006)

  - by Rob Farley

  I’m giving a presentation on May 12th at the Adelaide .Net User Group, around the topic of spatial data, and in particular, the visualization of said data. Given that it’s about one the larger types, this post should also count towards Michael Coles’ T-SQL Tuesday on BLOB data . I wrote recently about my experience with exploded data , but what I didn’t go on to talk about was how using a shapefile like this would translate into a scenario with a much larger number of shapes, such as all the postcode...(read more)

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• Database Maintenance Scripting Done Right

  - by KKline

  I first wrote about useful database maintenance scripts on my SQLBlog account way back in 2008. Hmmm - now that I think about it, I first wrote about my own useful database maintenance scripts in a journal called SQL Server Professional back in the mid-1990's on SQL Server v6.5 or some such. But I digress... Anyway, I pointed out a couple useful sites where you could get some good scripts that would take care of preventative maintenance on your SQL Server, such as index defragmentation, updating...(read more)

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• How to efficiently map tokens to code in a script interpreter?

  - by lithander

  I'm writing an interpreter for a simple scripting language where each line is a complete, executable command. (Like the instructions in assembler) When parsing a line I have to map the requested command to actual code. My current solution looks like this: std::string op, param1, param2; //parse line, identify op, param1, param2 ... //call command specific code if(op == "MOV") ExecuteMov(AsNumber(param1)); else if(op == "ROT") ExecuteRot(AsNumber(param1)); else if(op == "SZE") ExecuteSze(AsNumber(param1)); else if(op == "POS") ExecutePos((AsNumber(param1), AsNumber(param2)); else if(op == "DIR") ExecuteDir((AsNumber(param1), AsNumber(param2)); else if(op == "SET") ExecuteSet(param1, AsNumber(param2)); else if(op == "EVL") ... The more commands are supported the more string comparisions I'll have to do to identify and call the associated method. Can you point me to a more efficient implementation in the described scenario?

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• Slides and demo code for Columnstore Index session

  - by Hugo Kornelis

  Almost a week has passed after SQLBits X in London , so I guess it’s about time for me to share the slides and demo code of my session on columnstore indexes. After all, I promised people I would do that – especially when I found out that I had enough demos prepared to fill two sessions! I made some changes to the demo code. I added extra comments, not only to the demos I could not explain and run during the session, but also to the rest, so that people who missed the session will also be able to...(read more)

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• Designing a flexible tile-based engine

  - by Vee

  I'm trying to create a flexible tile-based game engine to make all sorts of non-realtime puzzle games, just as Bejeweled, Civilization, Sokoban, and so on. The first approach I had was to have a 2D array of Tile objects, and then have classes inheriting from Tile that represented the game objects. Unfortunately that way I couldn't stack more game elements on the same Tile without having a 3D array. Then I did something different: I still had the 2D array of Tile objects, but every Tile object contained a List where I put and different entities. This worked fine until 20 minutes ago, when I realized that it's too expensive to do many things, look at this example: I have a Wall entity. Every update I have to check the 8 adjacent Tiles, then check all of the entities in the Tile's List, check if any of those entities is a Wall, then finally draw the correct sprite. (This is done to draw walls that are next to each other seamlessly) The only solution I see now is having a 3D array, with many layers, that could suit every situation. But that way I can't stack two entities that share the same layer on the same tile. Whenever I want to do that I have to create a new layer. Is there a better solution? What would you do?

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• Add-ons for Firefox - Java Plugin has been blocked JRE versions below 1.6.0_31 or between 1.7.0 and 1.7.0_2

  - by user702295

  As Java 1.6u31 is not certified for use with EBS or Demantra, you may notice issues in relation to the Java plug-in.  Demantra Development is currently working to certify Java 1.6u31.  They are recommending that you upgrade to that version. EBS customers, should not be installing 1.6u31 as it is not certified.  If you do upgrade your browser, you will either need to downgrade to a lower release of Firefox or find a way of allowing Firefox to use the older version of the Java Plug-in.

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• Good DBAs Do Baselines

  - by Louis Davidson

  One morning, you wake up and feel funny. You can’t quite put your finger on it, but something isn’t quite right. What now? Unless you happen to be a hypochondriac, you likely drag yourself out of bed, get on with the day and gather more “evidence”. You check your symptoms over the next few days; do you feel the same, better, worse? If better, then great, it was some temporal issue, perhaps caused by an allergic reaction to some suspiciously spicy chicken. If the same or worse then you go to the doctor for some health advice, but armed with some data to share, and having ruled out certain possible causes that are fixed with a bit of rest and perhaps an antacid. Whether you realize it or not, in comparing how you feel one day to the next, you have taken baseline measurements. In much the same way, a DBA uses baselines to gauge the gauge health of their database servers. Of course, while SQL Server is very willing to share data regarding its health and activities, it has almost no idea of the difference between good and bad. Over time, experienced DBAs develop “mental” baselines with which they can gauge the health of their servers almost as easily as their own body. They accumulate knowledge of the daily, natural state of each part of their database system, and so know instinctively when one of their databases “feels funny”. Equally, they know when an “issue” is just a passing tremor. They see their SQL Server with all of its four CPU cores running close 100% and don’t panic anymore. Why? It’s 5PM and every day the same thing occurs when the end-of-day reports, which are very CPU intensive, are running. Equally, they know when they need to respond in earnest when it is the first time they have heard about an issue, even if it has been happening every day. Nevertheless, no DBA can retain mental baselines for every characteristic of their systems, so we need to collect physical baselines too. In my experience, surprisingly few DBAs do this very well. Part of the problem is that SQL Server provides a lot of instrumentation. If you look, you will find an almost overwhelming amount of data regarding user activity on your SQL Server instances, and use and abuse of the available CPU, I/O and memory. It seems like a huge task even to work out which data you need to collect, let alone start collecting it on a regular basis, managing its storage over time, and performing detailed comparative analysis. However, without baselines, though, it is very difficult to pinpoint what ails a server, just by looking at a single snapshot of the data, or to spot retrospectively what caused the problem by examining aggregated data for the server, collected over many months. It isn’t as hard as you think to get started. You’ve probably already established some troubleshooting queries of the type SELECT Value FROM SomeSystemTableOrView. Capturing a set of baseline values for such a query can be as easy as changing it as follows: INSERT into BaseLine.SomeSystemTable (value, captureTime) SELECT Value, SYSDATETIME() FROM SomeSystemTableOrView; Of course, there are monitoring tools that will collect and manage this baseline data for you, automatically, and allow you to perform comparison of metrics over different periods. However, to get yourself started and to prove to yourself (or perhaps the person who writes the checks for tools) the value of baselines, stick something similar to the above query into an agent job, running every hour or so, and you are on your way with no excuses! Then, the next time you investigate a slow server, and see x open transactions, y users logged in, and z rows added per hour in the Orders table, compare to your baselines and see immediately what, if anything, has changed!

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• Why after each restart, my local .NET sites take time to load for the first time?

  - by Saeed Neamati

  I'm developing sites based on .NET platform. I usually deploy these sites on my local IIS, so that I can test them and see their functionality before going live. However, each time I restart windows, it seems that sites take a long time to run for the first time. I know about JIT and I'm also aware of this question, but it doesn't answer my question. Does JIT happens every time you restart windows? Is it related to creation of w3wp.exe process? Why sites are so slow for the first request after each restart?

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• Webscale is all about sharding and its coming to SQL Azure

  - by simonsabin

  There are many that joke about developers always talking about webscale and needing to shard to be able to scale. In reality many systems, if not most, don’t need to be able to scale to numerous nodes because todays processing is so powerful. However in the cloud world where you don’t have 1 big box you have many little ones (instances) you need some way of sharding/federating/distributing data and load. I’ve mentioned before of a PDC presentation on whats coming in SQL Azure, well they’ve put some...(read more)

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• Object pools for efficient resource management

  - by GameDevEnthusiast

  How can I avoid using default new() to create each object? My previous demo had very unpleasant framerate hiccups during dynamic memory allocations (usually, when arrays are resized), and creating lots of small objects which often contain one pointer to some DirectX resource seems like an awful lot of waste. I'm thinking about: Creating a master look-up table to refer to objects by handles (for safety & ease of serialization), much like EntityList in source engine Creating a templated object pool, which will store items contiguously (more cache-friendly, fast iteration, etc.) and the stored elements will be accessed (by external systems) via the global lookup table. The object pool will use the swap-with-last trick for fast removal (it will invoke the object's ~destructor first) and will update the corresponding indices in the global table accordingly (when growing/shrinking/moving elements). The elements will be copied via plain memcpy(). Is it a good idea? Will it be safe to store objects of non-POD types (e.g. pointers, vtable) in such containers? Related post: Dynamic Memory Allocation and Memory Management

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• Improving Comparison Operators and Window Functions

  It is dangerous to assume that your data is sound. SQL already has intrinsic ways to cope with missing, or unknown data in its comparison predicate operators, or Theta operators. Can SQL be more effective in the way it deals with data quality? Joe Celko describes how the SQL Standard could soon evolve to deal with data in ways that allow aggregation and windowing in cases where the data quality is less than perfect

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• Optimized algorithm for line-sphere intersection in GLSL

  - by fernacolo

  Well, hello then! I need to find intersection between line and sphere in GLSL. Right now my solution is based on Paul Bourke's page and was ported to GLSL this way: // The line passes through p1 and p2: vec3 p1 = (...); vec3 p2 = (...); // Sphere center is p3, radius is r: vec3 p3 = (...); float r = ...; float x1 = p1.x; float y1 = p1.y; float z1 = p1.z; float x2 = p2.x; float y2 = p2.y; float z2 = p2.z; float x3 = p3.x; float y3 = p3.y; float z3 = p3.z; float dx = x2 - x1; float dy = y2 - y1; float dz = z2 - z1; float a = dx*dx + dy*dy + dz*dz; float b = 2.0 * (dx * (x1 - x3) + dy * (y1 - y3) + dz * (z1 - z3)); float c = x3*x3 + y3*y3 + z3*z3 + x1*x1 + y1*y1 + z1*z1 - 2.0 * (x3*x1 + y3*y1 + z3*z1) - r*r; float test = b*b - 4.0*a*c; if (test >= 0.0) { // Hit (according to Treebeard, "a fine hit"). float u = (-b - sqrt(test)) / (2.0 * a); vec3 hitp = p1 + u * (p2 - p1); // Now use hitp. } It works perfectly! But it seems slow... I'm new at GLSL. You can answer this questions in two ways: Tell me there is no solution, showing some proof or strong evidence. Tell me about GLSL features (vector APIs, primitive operations) that makes the above algorithm faster, showing some example. Thanks a lot!

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• Using JDBC to asynchronously read large Oracle table

  - by Ben George

  What strategies can be used to read every row in a large Oracle table, only once, but as fast as possible with JDBC & Java ? Consider that each row has non-trivial amounts of data (30 columns, including large text in some columns). Some strategies I can think of are: Single thread and read table. (Too slow, but listed for clarity) Read the id's into ConcurrentLinkedQueue, use threads to consume queue and query by id in batches. Read id's into a JMS queue, use workers to consume queue and query by id in batches. What other strategies could be used ? For the purpose of this question assume processing of rows to be free.

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• What are the Crappy Code Games - Tips on how to win?

  - by simonsabin

  This is part of a series on the Crappy Code Games The background Who can enter? What are the challenges? What are the prizes? Why should I attend? Tips on how to win Tips on how to win Each test has some different aspect that will define how you win. In this post we will give you some tips on how to try and win. As a starter why not watch some of the sessions from previous SQLBits Storage sessions Sessions on IO The background Who can enter? What are the challenges? What are the prizes? Why should...(read more)

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• How to avoid the exception “Substitution controls cannot be used in cached User Controls or cached M

  - by DigiMortal

  Recently I wrote example about using user controls with donut caching. Because cache substitutions are not allowed inside partially cached controls you may get the error Substitution controls cannot be used in cached User Controls or cached Master Pages when breaking this rule. In this posting I will introduce some strategies that help to avoid this error. How Substitution control checks its location? Substitution control uses the following check in its OnPreRender method. protected internal override void OnPreRender(EventArgs e) {     base.OnPreRender(e);     for (Control control = this.Parent; control != null;          control = control.Parent)     {         if (control is BasePartialCachingControl)         {             throw new HttpException(SR.GetString("Substitution_CannotBeInCachedControl"));         }     } } It traverses all the control tree up to top from its parent to find at least one control that is partially cached. If such control is found then exception is thrown. Reusing the functionality If you want to do something by yourself if your control may cause exception mentioned before you can use the same code. I modified the previously shown code to be method that can be easily moved to user controls base class if you have some. If you don’t you can use it in controls where you need this check. protected bool IsInsidePartialCachingControl() {     for (Control control = Parent; control != null;         control = control.Parent)         if (control is BasePartialCachingControl)             return true;       return false; } Now it is up to you how to handle the situation where your control with substitutions is child of some partially cache control. You can add here also some debug level output so you can see exactly what controls in control hierarchy are cached and cause problems.

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• Make OpenGL game perform better

  - by Csabi

  I have programmed an OpenGL game which just contains one F1 car and a track. It is very simple and only uses around of 10'000 - 20'000 triangles. It should run on any PC but it won't, it needs a really good graphics-card to run at a decent framerate. Can you write some methods or links to sites which would help me make my scene/game more efective? my game can be downloaded from here or directly from here

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• My laptop hangs a lot

  - by Salahuddin

  My laptop is 1G ram and 120G hard-disk 1.68HZ processor , I've both Ubuntu and Windows7 on my machine For the last few days, my laptop, running Ubuntu 11.10 has been hanging a lot. A lot of the time, the touchpad won't work for unknown reasons, and I have to connect a USB mouse to be able to move the pointer on the screen. When browsing the web, the browser hangs a lot, and I have to restart the laptop to refresh it. I know that there is a hotkey to force Ubuntu to refresh when it hangs, but it doesn't work here.These problems happens only on ubuntu not on windows 7... How do I make Ubuntu light and fast? Help me, please.

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• SCOM, 90 Days In, I

  - by merrillaldrich

  At my office we’re about 90 days into our implementation of System Center Operations Manager for Windows Server and SQL Server monitoring. All in all it’s been a good experience, and I’m really excited to have access to this tool. I’ve logged a fair number of years as a DBA on products like Idera’s SQL Diagnostic Manager and Quest Spotlight on SQL Server Enterprise (and “roll-your-own” solutions) in smaller environments, and liked them, but they always, in my experience, struggled with really large...(read more)

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