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  • Red Gate Coder interviews: Alex Davies

    - by Michael Williamson
    Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

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  • For virtual machines, when SMP is available on the host, should guest also have SMP setup?

    - by supercheetah
    I'm trying to find out the best "bang for my buck" so to speak in regards to virtual machines, and SMP. I have an Intel Core 2 Duo, which of course has two cores and the VT extensions, and I'm running Ubuntu Linux (host) on it with VirtualBox, which has Windows Vista (guest). Currently I've got the guest machine setup for two processors to give Windows a chance to manage its own parallelism, but I'm not certain that it's any faster. I've tried it with just one processor, but it's hard to tell if it's any better. Any thoughts? Should the guest have two processors setup?

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  • Trying to determine the correct number of XFS allocation groups for postgresql server on Linux

    - by HBlend
    I am running a postgres 8.4.5 server on the linux 2.6.33.7 kernel on an 8 disk raid array with an LSI controller. Most of the tables are around 1GB or less. I know that XFS uses allocation groups (AG) to achieve I/O parallelism. My first question is, does this mean that if two tables are in the same AG, all I/O requests are queued to both of them if either is being read from/written to? If so, I assume I would want to spread my tables across as my allocation groups as possible, correct? Wouldn't this ensure that multiple users querying different tables would get the best performance?

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  • SQL Spatial: Getting “nearest” calculations working properly

    - by Rob Farley
    If you’ve ever done spatial work with SQL Server, I hope you’ve come across the ‘nearest’ problem. You have five thousand stores around the world, and you want to identify the one that’s closest to a particular place. Maybe you want the store closest to the LobsterPot office in Adelaide, at -34.925806, 138.605073. Or our new US office, at 42.524929, -87.858244. Or maybe both! You know how to do this. You don’t want to use an aggregate MIN or MAX, because you want the whole row, telling you which store it is. You want to use TOP, and if you want to find the closest store for multiple locations, you use APPLY. Let’s do this (but I’m going to use addresses in AdventureWorks2012, as I don’t have a list of stores). Oh, and before I do, let’s make sure we have a spatial index in place. I’m going to use the default options. CREATE SPATIAL INDEX spin_Address ON Person.Address(SpatialLocation); And my actual query: WITH MyLocations AS (SELECT * FROM (VALUES ('LobsterPot Adelaide', geography::Point(-34.925806, 138.605073, 4326)),                        ('LobsterPot USA', geography::Point(42.524929, -87.858244, 4326))                ) t (Name, Geo)) SELECT l.Name, a.AddressLine1, a.City, s.Name AS [State], c.Name AS Country FROM MyLocations AS l CROSS APPLY (     SELECT TOP (1) *     FROM Person.Address AS ad     ORDER BY l.Geo.STDistance(ad.SpatialLocation)     ) AS a JOIN Person.StateProvince AS s     ON s.StateProvinceID = a.StateProvinceID JOIN Person.CountryRegion AS c     ON c.CountryRegionCode = s.CountryRegionCode ; Great! This is definitely working. I know both those City locations, even if the AddressLine1s don’t quite ring a bell. I’m sure I’ll be able to find them next time I’m in the area. But of course what I’m concerned about from a querying perspective is what’s happened behind the scenes – the execution plan. This isn’t pretty. It’s not using my index. It’s sucking every row out of the Address table TWICE (which sucks), and then it’s sorting them by the distance to find the smallest one. It’s not pretty, and it takes a while. Mind you, I do like the fact that it saw an indexed view it could use for the State and Country details – that’s pretty neat. But yeah – users of my nifty website aren’t going to like how long that query takes. The frustrating thing is that I know that I can use the index to find locations that are within a particular distance of my locations quite easily, and Microsoft recommends this for solving the ‘nearest’ problem, as described at http://msdn.microsoft.com/en-au/library/ff929109.aspx. Now, in the first example on this page, it says that the query there will use the spatial index. But when I run it on my machine, it does nothing of the sort. I’m not particularly impressed. But what we see here is that parallelism has kicked in. In my scenario, it’s split the data up into 4 threads, but it’s still slow, and not using my index. It’s disappointing. But I can persuade it with hints! If I tell it to FORCESEEK, or use my index, or even turn off the parallelism with MAXDOP 1, then I get the index being used, and it’s a thing of beauty! Part of the plan is here: It’s massive, and it’s ugly, and it uses a TVF… but it’s quick. The way it works is to hook into the GeodeticTessellation function, which is essentially finds where the point is, and works out through the spatial index cells that surround it. This then provides a framework to be able to see into the spatial index for the items we want. You can read more about it at http://msdn.microsoft.com/en-us/library/bb895265.aspx#tessellation – including a bunch of pretty diagrams. One of those times when we have a much more complex-looking plan, but just because of the good that’s going on. This tessellation stuff was introduced in SQL Server 2012. But my query isn’t using it. When I try to use the FORCESEEK hint on the Person.Address table, I get the friendly error: Msg 8622, Level 16, State 1, Line 1 Query processor could not produce a query plan because of the hints defined in this query. Resubmit the query without specifying any hints and without using SET FORCEPLAN. And I’m almost tempted to just give up and move back to the old method of checking increasingly large circles around my location. After all, I can even leverage multiple OUTER APPLY clauses just like I did in my recent Lookup post. WITH MyLocations AS (SELECT * FROM (VALUES ('LobsterPot Adelaide', geography::Point(-34.925806, 138.605073, 4326)),                        ('LobsterPot USA', geography::Point(42.524929, -87.858244, 4326))                ) t (Name, Geo)) SELECT     l.Name,     COALESCE(a1.AddressLine1,a2.AddressLine1,a3.AddressLine1),     COALESCE(a1.City,a2.City,a3.City),     s.Name AS [State],     c.Name AS Country FROM MyLocations AS l OUTER APPLY (     SELECT TOP (1) *     FROM Person.Address AS ad     WHERE l.Geo.STDistance(ad.SpatialLocation) < 1000     ORDER BY l.Geo.STDistance(ad.SpatialLocation)     ) AS a1 OUTER APPLY (     SELECT TOP (1) *     FROM Person.Address AS ad     WHERE l.Geo.STDistance(ad.SpatialLocation) < 5000     AND a1.AddressID IS NULL     ORDER BY l.Geo.STDistance(ad.SpatialLocation)     ) AS a2 OUTER APPLY (     SELECT TOP (1) *     FROM Person.Address AS ad     WHERE l.Geo.STDistance(ad.SpatialLocation) < 20000     AND a2.AddressID IS NULL     ORDER BY l.Geo.STDistance(ad.SpatialLocation)     ) AS a3 JOIN Person.StateProvince AS s     ON s.StateProvinceID = COALESCE(a1.StateProvinceID,a2.StateProvinceID,a3.StateProvinceID) JOIN Person.CountryRegion AS c     ON c.CountryRegionCode = s.CountryRegionCode ; But this isn’t friendly-looking at all, and I’d use the method recommended by Isaac Kunen, who uses a table of numbers for the expanding circles. It feels old-school though, when I’m dealing with SQL 2012 (and later) versions. So why isn’t my query doing what it’s supposed to? Remember the query... WITH MyLocations AS (SELECT * FROM (VALUES ('LobsterPot Adelaide', geography::Point(-34.925806, 138.605073, 4326)),                        ('LobsterPot USA', geography::Point(42.524929, -87.858244, 4326))                ) t (Name, Geo)) SELECT l.Name, a.AddressLine1, a.City, s.Name AS [State], c.Name AS Country FROM MyLocations AS l CROSS APPLY (     SELECT TOP (1) *     FROM Person.Address AS ad     ORDER BY l.Geo.STDistance(ad.SpatialLocation)     ) AS a JOIN Person.StateProvince AS s     ON s.StateProvinceID = a.StateProvinceID JOIN Person.CountryRegion AS c     ON c.CountryRegionCode = s.CountryRegionCode ; Well, I just wasn’t reading http://msdn.microsoft.com/en-us/library/ff929109.aspx properly. The following requirements must be met for a Nearest Neighbor query to use a spatial index: A spatial index must be present on one of the spatial columns and the STDistance() method must use that column in the WHERE and ORDER BY clauses. The TOP clause cannot contain a PERCENT statement. The WHERE clause must contain a STDistance() method. If there are multiple predicates in the WHERE clause then the predicate containing STDistance() method must be connected by an AND conjunction to the other predicates. The STDistance() method cannot be in an optional part of the WHERE clause. The first expression in the ORDER BY clause must use the STDistance() method. Sort order for the first STDistance() expression in the ORDER BY clause must be ASC. All the rows for which STDistance returns NULL must be filtered out. Let’s start from the top. 1. Needs a spatial index on one of the columns that’s in the STDistance call. Yup, got the index. 2. No ‘PERCENT’. Yeah, I don’t have that. 3. The WHERE clause needs to use STDistance(). Ok, but I’m not filtering, so that should be fine. 4. Yeah, I don’t have multiple predicates. 5. The first expression in the ORDER BY is my distance, that’s fine. 6. Sort order is ASC, because otherwise we’d be starting with the ones that are furthest away, and that’s tricky. 7. All the rows for which STDistance returns NULL must be filtered out. But I don’t have any NULL values, so that shouldn’t affect me either. ...but something’s wrong. I do actually need to satisfy #3. And I do need to make sure #7 is being handled properly, because there are some situations (eg, differing SRIDs) where STDistance can return NULL. It says so at http://msdn.microsoft.com/en-us/library/bb933808.aspx – “STDistance() always returns null if the spatial reference IDs (SRIDs) of the geography instances do not match.” So if I simply make sure that I’m filtering out the rows that return NULL… …then it’s blindingly fast, I get the right results, and I’ve got the complex-but-brilliant plan that I wanted. It just wasn’t overly intuitive, despite being documented. @rob_farley

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  • CodePlex Daily Summary for Sunday, December 26, 2010

    CodePlex Daily Summary for Sunday, December 26, 2010Popular ReleasesNoSimplerAccounting: NoSimplerAccounting 6.0: -Fixed a bug in expense category report.Temporary Data Storage Folder: TDS Folder source code: This is latest version 0.2 Beta code. To know the password request at neutron.request@gmail.comNHibernate Mapping Generator: NHibernate Mapping Generator 2.0: Added support for Postgres (Thanks to Angelo)NewLife XCode: XCode v6.5.2010.1223 ????(????v3.5??): XCode v6.5.2010.1223 ????,??: NewLife.Core ??? NewLife.Net ??? XControl ??? XTemplate ????,??C#?????? XAgent ???? NewLife.CommonEnitty ??????(???,XCode??????) XCode?? ?????????,??????????????????,?????95% XCode v3.5.2009.0714 ??,?v3.5?v6.0???????????????,?????????。v3.5???????????,??????????????。 XCoder ??XTemplate?????????,????????XCode??? XCoder_Src ???????(????XTemplate????),??????????????????Windows Workflow Foundation on Codeplex: Microsoft.Activities.UnitTesting 1.71: New in this release Episode as Tasks using the Task Parallel Library CHM Help file now included in release. StyleCop compliance is resulting in massive refatoring but should not cause breaking changes Breaking Change DefaultTimeout is now a TimeSpan Removed default parameters using int timeout = DefaultTimeout and added overloads insteadMiniTwitter: 1.64: MiniTwitter 1.64 ???? ?? 1.63 ??? URL ??????????????Ajax ASP.Net Forum: InSeCla Forum Software v0.1.9: *VERSION: 0.1.9* HAPPY CHRISTMAS FEATURES ADDED Added features customizabled per category level (Customize at ADMIN/Categories Tab) Allow Anonymous Threads, Allow Anonymous Post Virtual URLs (friendly urls) has finally added And you can have some forum (category) using virtual urls and other using normal urls. Check !, as this improve the SEO indexing results Moderation Instant On: Delete Thread, Move Thread Available to users being members of moderators or administrators InstantO...VivoSocial: VivoSocial 7.4.0: Please see changes: http://support.vivoware.com/project/ChangeLog.aspx?PROJID=48Umbraco CMS: Umbraco 4.6 Beta - codename JUNO: The Umbraco 4.6 beta (codename JUNO) release contains many new features focusing on an improved installation experience, a number of robust developer features, and contains more than 89 bug fixes since the 4.5.2 release. Improved installer experience Updated Starter Kits (Simple, Blog, Personal, Business) Beautiful, free, customizable skins included Skinning engine and Skin customization (see Skinning Documentation Kit) Default dashboards on install with hide option Updated Login t...SSH.NET Library: 2010.12.23: This release includes some bug fixes and few new fetures. Fixes Allow to retrieve big directory structures ssh-dss algorithm is fixed Populate sftp file attributes New Features Support for passhrase when private key is used Support added for diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha256 and diffie-hellman-group-exchange-sha1 key exchange algorithms Allow to provide multiple key files for authentication Add support for "keyboard-interactive" authentication method...ASP.NET MVC SiteMap provider: MvcSiteMapProvider 2.3.0: Using NuGet?MvcSiteMapProvider is also listed in the NuGet feed. Learn more... Like the project? Consider a donation!Donate via PayPal via PayPal. Release notesThis will be the last release targeting ASP.NET MVC 2 and .NET 3.5. MvcSiteMapProvider 3.0.0 will be targeting ASP.NET MVC 3 and .NET 4 Web.config setting skipAssemblyScanOn has been deprecated in favor of excludeAssembliesForScan and includeAssembliesForScan ISiteMapNodeUrlResolver is now completely responsible for generating th...SuperSocket, an extensible socket application framework: SuperSocket 1.3 beta 2: Compared with SuperSocket 1.3 beta 1, the changes listed below have been done in SuperSocket 1.3 beta 2: added supports for .NET 3.5 replaced Logging Application Block of EntLib with Log4Net improved the code about logging fixed a bug in QuickStart sample project added IPv6 supportTibiaPinger: TibiaPinger v1.0: TibiaPinger v1.0Media Companion: Media Companion 3.400: Extract the entire archive to a folder which has user access rights, eg desktop, documents etc. A manual is included to get you startedMulticore Task Framework: MTF 1.0.1: Release 1.0.1 of Multicore Task Framework.SQL Monitor - tracking sql server activities: SQL Monitor 3.0 alpha 7: 1. added script save/load in user query window 2. fixed problem with connection dialog when choosing windows auth but still ask for user name 3. auto open user table when double click one table node 4. improved alert message, added log only methodEnhSim: EnhSim 2.2.6 ALPHA: 2.2.6 ALPHAThis release supports WoW patch 4.03a at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - Fixing up some r...ASP.NET MVC Project Awesome (jQuery Ajax helpers): 1.4.3: Helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager new stuff: Improvements for confirm, popup, popup form RenderView controller extension the user experience for crud in live demo has been substantially improved + added search all the features are shown in the live demoGanttPlanner: GanttPlanner V1.0: GanttPlanner V1.0 include GanttPlanner.dll and also a Demo application.N2 CMS: 2.1 release candidate 3: * Web platform installer support available N2 is a lightweight CMS framework for ASP.NET. It helps you build great web sites that anyone can update. Major Changes Support for auto-implemented properties ({get;set;}, based on contribution by And Poulsen) A bunch of bugs were fixed File manager improvements (multiple file upload, resize images to fit) New image gallery Infinite scroll paging on news Content templates First time with N2? Try the demo site Download one of the templ...New ProjectsA.I. Semantic Net Tests: A test using "semantic net" artificial intelligence developed in C++.Awesome.ClientID: Awesome.ClientID is a HTTPModule which serializes the ClientID of server controls, and page/usercontrol properties to a Json to make working with JavaScript easier without the need for outputting ClientID's. It's a solution for clean ClientIDs for .NET 2.0/3.5BitTweet: BitTweet is a fast, simple and easy to use Twitter client with tweeting, reading and writing functions included. It is know for being the most secure and fast Twitter client out there! It is written in Visual Basic .NET 2008. ~Tweet in a bit!CarRental001: carCrudo: CRUDO - The MCG (Model-Controller-Generator) CGF (Code Generation Framework) Visit The Project HomePage: http://adityayadav.com/CRUDO_The_MCG_Model_Controller_Generator_CGF_Code_Generation_Framework.aspx Licenses: 1) GPL v2 2) Commercial (contact us for information)Effeks: FX trading sample application sing prismEnhanced WebPart: Enhanced Webpart is a webpart with enhanced properties editor. It allows you display properties of most common types, and provides easy way to add custom controls to display your own types in webpart properties editor. Enhanced Webpart fully supports localization.Esteffin's graphic: Esercitazioni grafica 2010farasun: Source code Repository for farasun.wordpress.comGCTF: Desafio .NET Realizado na FACISAImgshow Plugin for Windows Live Writer: By using Imgshow Query you are able to publish multimedia content such as Youtube, Facebook Video, PDF, and other Imgshow supported service.Instant Messenger Using WPF and WCF: instant messenger using wcf and wpfjMenu: Create a dotnetnuke module that cover all kind of jquery menu pluginsMcopy API: Copy all files and directores in windows shell. Support long path (less then 32000 chars) and network path (eg. \\server\share or \\127.0.0.1\share)MOSSWebServices: This project contains code for interacting with the 21 web services provided by MOSS. This is targeted towards WSS developers This currently contains code to interact with "UserGroups" web service. I will keep adding code to interact with other MOSS web services soon. Nest Hub - Twitter Client: Nest Hub is a free Twitter client for PC. It's developed in VB.NET.Neural Networks Library: Neural networks Library by SefnajParallelism: Parallelism- Unified Parallel & Concurrency Framework Visit the Project HomePage: http://adityayadav.com/Parallelism.aspx Licenses: 1) GPL v2 2) Commercial (contact us for information)PDF IRM Protector For SharePoint 2007 And 2010: The PDF IRM Protector controls the conversion of PDF documents to their encrypted, rights-managed format and the decryption of PDF documents from their rights-managed format back to their original format. The project targets both SharePoint 2007 and 2010. PHP Form Validator - Isis: Project Isis simplifies the process of form validation for PHP. Offering a robust flag and function system, allowing you to encode the forms with the correct validation data and be done.Recycle Me: Open Source Project is to help and educate people in regarding reuse and recycling of daily life items. This is a Social project so we need funds for research and surveys. Volunteers are most welcome to contribute and certifications for their participation are available. ThanksSencha ExtJS Import Library for Script#: Script# import library for Sencha Ext JS Javascript Framework Separating Vertices: Given a graph as a collection of edges and vertices, it identifies the separating vertices, biconnected components, and edges. SIG - SISTEMA DE GESTÃO INTERNA: Projeto feito para a empresa MODEMTELECOM, consultoria em telecomunicoções.Smart Card COM: Smart Card COM Library, useful to access smart cards from a Web page in Internet ExplorerSocial Hub: Social HubStock Research: Test project for stocke researchtaokeba: ????????????????????,???????????。Temporary Data Storage Folder: This software creates a folder that stores temporary data that you want to store for temporary tasks. Temporary tasks such as storing a file that is to be deleted after some time. It automatically deleted those files on exit. Learn more at www.neutronsoftwares.weebly.comTukUI Updater: A OpenSource Windows Updater tool for the World of Warcraft(R) addon TukUI Developed in .NET 3.5 Discusion thread are found at the official TukUI forums: http://www.tukui.org/v2/forums/topic.php?id=4982 WebUtil: This is a project for using all of features by the web.

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  • Java Spotlight Episode 86: Tony Printezis on Garbage Collection First

    - by Roger Brinkley
    Interview with Tony Printezis on Garbage Collection First (GC1). Joining us this week on the Java All Star Developer Panel is Arun Gupta, Java EE Guy. 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 JSR 358: A major revison of the Java Community Process - JCP 3.Next JAX-RS 2.0 Early Draft- Third Edition Events June 11-14, Cloud Computing Expo, New York City June 12, Boulder JUG June 13, Denver JUG June 13, Eclipse Juno DemoCamp, Redwoood Shore June 13, JUG Münster June 14, Java Klassentreffen, Vienna, Austria June 18-20, QCon, New York City June 19, CJUG, Chicago June 20, 1871, Chicago June 26-28, Jazoon, Zurich, Switzerland Jun 27, Houston JUG ?? July 5, Java Forum, Stuttgart, Germany Jul 13-14, IndicThreads, Delhi July 30-August 1, JVM Language Summit, Santa Clara Feature InterviewTony Printezis is a Principal Member of Technical Staff at Oracle, based in Burlington, MA. He has been contributing to the Java HotSpot Virtual Machine since 2006. He spends most of his time working on dynamic memory management for the Java platform, concentrating on performance, scalability, responsiveness, parallelism, and visualization of garbage collectors. He obtained a Ph.D. in 2000 and a BSc (Hons) in 1995, both from the University of Glasgow in Scotland. In addition, he is a JavaOne Rock Star, a title awarded for his highly rated JavaOne session on GC. Mail Bag What’s Cool JavaOne content selection is complete. Notifications done.

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  • SQL SERVER – Weekly Series – Memory Lane – #039

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 FQL – Facebook Query Language Facebook list following advantages of FQL: Condensed XML reduces bandwidth and parsing costs. More complex requests can reduce the number of requests necessary. Provides a single consistent, unified interface for all of your data. It’s fun! UDF – Get the Day of the Week Function The day of the week can be retrieved in SQL Server by using the DatePart function. The value returned by the function is between 1 (Sunday) and 7 (Saturday). To convert this to a string representing the day of the week, use a CASE statement. UDF – Function to Get Previous And Next Work Day – Exclude Saturday and Sunday While reading ColdFusion blog of Ben Nadel Getting the Previous Day In ColdFusion, Excluding Saturday And Sunday, I realize that I use similar function on my SQL Server Database. This function excludes the Weekends (Saturday and Sunday), and it gets previous as well as next work day. Complete Series of SQL Server Interview Questions and Answers Data Warehousing Interview Questions and Answers – Introduction Data Warehousing Interview Questions and Answers – Part 1 Data Warehousing Interview Questions and Answers – Part 2 Data Warehousing Interview Questions and Answers – Part 3 Data Warehousing Interview Questions and Answers Complete List Download 2008 Introduction to Log Viewer In SQL Server all the windows event logs can be seen along with SQL Server logs. Interface for all the logs is same and can be launched from the same place. This log can be exported and filtered as well. DBCC SHRINKFILE Takes Long Time to Run If you are DBA who are involved with Database Maintenance and file group maintenance, you must have experience that many times DBCC SHRINKFILE operations takes a long time but any other operations with Database are relatively quicker. mssqlsystemresource – Resource Database The purpose of resource database is to facilitates upgrading to the new version of SQL Server without any hassle. In previous versions whenever version of SQL Server was upgraded all the previous version system objects needs to be dropped and new version system objects to be created. 2009 Puzzle – Write Script to Generate Primary Key and Foreign Key In SQL Server Management Studio (SSMS), there is no option to script all the keys. If one is required to script keys they will have to manually script each key one at a time. If database has many tables, generating one key at a time can be a very intricate task. I want to throw a question to all of you if any of you have scripts for the same purpose. Maximizing View of SQL Server Management Studio – Full Screen – New Screen I had explained the following two different methods: 1) Open Results in Separate Tab - This is a very interesting method as result pan shows up in a different tab instead of the splitting screen horizontally. 2) Open SSMS in Full Screen - This works always and to its best. Not many people are aware of this method; hence, very few people use it to enhance performance. 2010 Find Queries using Parallelism from Cached Plan T-SQL script gets all the queries and their execution plan where parallelism operations are kicked up. Pay attention there is TOP 10 is used, if you have lots of transactional operations, I suggest that you change TOP 10 to TOP 50 This is the list of the all the articles in the series of computed columns. SQL SERVER – Computed Column – PERSISTED and Storage This article talks about how computed columns are created and why they take more storage space than before. SQL SERVER – Computed Column – PERSISTED and Performance This article talks about how PERSISTED columns give better performance than non-persisted columns. SQL SERVER – Computed Column – PERSISTED and Performance – Part 2 This article talks about how non-persisted columns give better performance than PERSISTED columns. SQL SERVER – Computed Column and Performance – Part 3 This article talks about how Index improves the performance of Computed Columns. SQL SERVER – Computed Column – PERSISTED and Storage – Part 2 This article talks about how creating index on computed column does not grow the row length of table. SQL SERVER – Computed Columns – Index and Performance This article summarized all the articles related to computed columns. 2011 SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 21 of 31 What is Data Warehousing? What is Business Intelligence (BI)? What is a Dimension Table? What is Dimensional Modeling? What is a Fact Table? What are the Fundamental Stages of Data Warehousing? What are the Different Methods of Loading Dimension tables? Describes the Foreign Key Columns in Fact Table and Dimension Table? What is Data Mining? What is the Difference between a View and a Materialized View? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 22 of 31 What is OLTP? What is OLAP? What is the Difference between OLTP and OLAP? What is ODS? What is ER Diagram? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 23 of 31 What is ETL? What is VLDB? Is OLTP Database is Design Optimal for Data Warehouse? If denormalizing improves Data Warehouse Processes, then why is the Fact Table is in the Normal Form? What are Lookup Tables? What are Aggregate Tables? What is Real-Time Data-Warehousing? What are Conformed Dimensions? What is a Conformed Fact? How do you Load the Time Dimension? What is a Level of Granularity of a Fact Table? What are Non-Additive Facts? What is a Factless Facts Table? What are Slowly Changing Dimensions (SCD)? SQL SERVER – Interview Questions and Answers – Frequently Asked Questions – Data Warehousing Concepts – Day 24 of 31 What is Hybrid Slowly Changing Dimension? What is BUS Schema? What is a Star Schema? What Snow Flake Schema? Differences between the Star and Snowflake Schema? What is Difference between ER Modeling and Dimensional Modeling? What is Degenerate Dimension Table? Why is Data Modeling Important? What is a Surrogate Key? What is Junk Dimension? What is a Data Mart? What is the Difference between OLAP and Data Warehouse? What is a Cube and Linked Cube with Reference to Data Warehouse? What is Snapshot with Reference to Data Warehouse? What is Active Data Warehousing? What is the Difference between Data Warehousing and Business Intelligence? What is MDS? Explain the Paradigm of Bill Inmon and Ralph Kimball. SQL SERVER – Azure Interview Questions and Answers – Guest Post by Paras Doshi – Day 25 of 31 Paras Doshi has submitted 21 interesting question and answers for SQL Azure. 1.What is SQL Azure? 2.What is cloud computing? 3.How is SQL Azure different than SQL server? 4.How many replicas are maintained for each SQL Azure database? 5.How can we migrate from SQL server to SQL Azure? 6.Which tools are available to manage SQL Azure databases and servers? 7.Tell me something about security and SQL Azure. 8.What is SQL Azure Firewall? 9.What is the difference between web edition and business edition? 10.How do we synchronize On Premise SQL server with SQL Azure? 11.How do we Backup SQL Azure Data? 12.What is the current pricing model of SQL Azure? 13.What is the current limitation of the size of SQL Azure DB? 14.How do you handle datasets larger than 50 GB? 15.What happens when the SQL Azure database reaches Max Size? 16.How many databases can we create in a single server? 17.How many servers can we create in a single subscription? 18.How do you improve the performance of a SQL Azure Database? 19.What is code near application topology? 20.What were the latest updates to SQL Azure service? 21.When does a workload on SQL Azure get throttled? SQL SERVER – Interview Questions and Answers – Guest Post by Malathi Mahadevan – Day 26 of 31 Malachi had asked a simple question which has several answers. Each answer makes you think and ponder about the reality of the IT world. Look at the simple question – ‘What is the toughest challenge you have faced in your present job and how did you handle it’? and its various answers. Each answer has its own story. SQL SERVER – Interview Questions and Answers – Guest Post by Rick Morelan – Day 27 of 31 Rick Morelan of Joes2Pros has written an excellent blog post on the subject how to find top N values. Most people are fully aware of how the TOP keyword works with a SELECT statement. After years preparing so many students to pass the SQL Certification I noticed they were pretty well prepared for job interviews too. Yes, they would do well in the interview but not great. There seemed to be a few questions that would come up repeatedly for almost everyone. Rick addresses similar questions in his lucid writing skills. 2012 Observation of Top with Index and Order of Resultset SQL Server has lots of things to learn and share. It is amazing to see how people evaluate and understand different techniques and styles differently when implementing. The real reason may be absolutely different but we may blame something totally different for the incorrect results. Read the blog post to learn more. How do I Record Video and Webcast How to Convert Hex to Decimal or INT Earlier I asked regarding a question about how to convert Hex to Decimal. I promised that I will post an answer with Due Credit to the author but never got around to post a blog post around it. Read the original post over here SQL SERVER – Question – How to Convert Hex to Decimal. Query to Get Unique Distinct Data Based on Condition – Eliminate Duplicate Data from Resultset The natural reaction will be to suggest DISTINCT or GROUP BY. However, not all the questions can be solved by DISTINCT or GROUP BY. Let us see the following example, where a user wanted only latest records to be displayed. Let us see the example to understand further. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Parallel Computing Platform Developer Lab

    - by Daniel Moth
    This is an exciting announcement that I must share: "Microsoft Developer & Platform Evangelism, in collaboration with the Microsoft Parallel Computing Platform product team, is hosting a developer lab at the Platform Adoption Center on April 12-15, 2010.  This event is for Microsoft Partners and Customers seeking to incorporate either .NET Framework 4 or Visual C++ 2010 parallelism features into their new or existing applications, and to gain expertise with new Visual Studio 2010 tools including the Parallel Tasks and Parallel Stacks debugger toolwindows, and the Concurrency Visualizer in the profiler. Opportunities for attendees include: Gain expert design assistance with your Parallel Computing Platform based solution. Develop a solution prototype in collaboration with Microsoft Software Engineers. Attend topical presentations and “chalk-talk” sessions. Your team will be assigned private, secure offices for confidential collaboration activities. The event has limited capacity, thus enrollment is based on an application process.   Please download and complete the application form then return it to the event management team per instructions included within the form.  Applications will be evaluated based upon the technical solution scenario along with indicated project readiness timelines.  Microsoft event management team members may contact you directly for additional clarification and discussion of your project scenario during the nomination process." Comments about this post welcome at the original blog.

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  • The Cloud is STILL too slow!

    - by harry.foxwell(at)oracle.com
    If you've been in the computing industry sufficiently long enough to remember dialup modems and other "ancient" technologies, you might be tempted to marvel at today's wonderfully powerful multicore PCs, ginormous disks, and blazingly fast networks.  Wow, you're in Internet Nirvana, right!  Well, no, not by a long shot.Considering the exponentially growing expectations of what the Web, that is, "the Cloud", is supposed to provide, today's Web/Cloud services are still way too slow.Already we are seeing cloud-enabled consumer devices that are stressing even the most advanced public network services.  Like the iPad and its competitors, ever more powerful smart-phones, and an imminent hoard of special purpose gadgets such as the proposed "cloud camera" (see http://gdgt.com/discuss/it-time-cloud-camera-found-out-cnr/ ).And at the same time that the number and type of cloud services are growing, user tolerance for even the slightest of download delays is rapidly decreasing.  Ten years ago Web developers followed the "8-Second Rule", (average time a typical Web user would tolerate for a page to download and render).  Not anymore; now it's less than 3 seconds, and only a bit longer for mobile devices (see http://www.technologyreview.com/files/54902/GoogleSpeed_charts.pdf).  How spoiled we've become!Google, among others, recognizes this problem and is working to encourage the development of a faster Web (see http://www.technologyreview.com/web/32338/). They, along with their competitors and ISPs, will have to encourage and support significantly better Web performance in order to provide the types of services envisioned for the Cloud.  How will they do this? Through the development of faster components, better use of caching technologies, and the really tough one - exploiting parallelism. Not that parallel technologies like multicore processors are hard to build...we already have them.  It's just that we're not that good yet at using them effectively.  And if we don't get better, users will abandon cloud-based services...in less than 3 seconds.

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  • SQL Saturday #220 - Atlanta - Pre-Conference Scholarships!

    - by Most Valuable Yak (Rob Volk)
    We Want YOU…To Learn! AtlantaMDF and Idera are teaming up to find a few good people. If you are: A student looking to work in the database or business intelligence fields A database professional who is between jobs or wants a better one A developer looking to step up to something new On a limited budget and can’t afford professional SQL Server training Able to attend training from 9 to 5 on May 17, 2013 AtlantaMDF is presenting 5 Pre-Conference Sessions (pre-cons) for SQL Saturday #220! And thanks to Idera’s sponsorship, we can offer one free ticket to each of these sessions to eligible candidates! That means one scholarship per Pre-Con! One Recipient Each will Attend: Denny Cherry: SQL Server Security http://sqlsecurity.eventbrite.com/ Adam Machanic: Surfing the Multicore Wave: Processors, Parallelism, and Performance http://surfmulticore.eventbrite.com/ Stacia Misner: Languages of BI http://languagesofbi.eventbrite.com/ Bill Pearson: Practical Self-Service BI with PowerPivot for Excel http://selfservicebi.eventbrite.com/ Eddie Wuerch: The DBA Skills Upgrade Toolkit http://dbatoolkit.eventbrite.com/ If you are interested in attending these pre-cons send an email by April 30, 2013 to [email protected] and tell us: Why you are a good candidate to receive this scholarship Which sessions you’d like to attend, and why (list multiple sessions in order of preference) What the session will teach you and how it will help you achieve your goals The emails will be evaluated by the good folks at Midlands PASS in Columbia, SC. The recipients will be notified by email and announcements made on May 6, 2013. GOOD LUCK! P.S. - Don't forget that SQLSaturday #220 offers free* training in addition to the pre-cons! You can find more information about SQL Saturday #220 at http://www.sqlsaturday.com/220/eventhome.aspx. View the scheduled sessions at http://www.sqlsaturday.com/220/schedule.aspx and register for them at http://www.sqlsaturday.com/220/register.aspx. * Registration charges a $10 fee to cover lunch expenses.

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  • OpenGL CPU vs. GPU

    - by Nitrex88
    So I've always been under the impression that doing work on the GPU is always faster than on the CPU. Because of this, in OpenGL, I usually try to do intensive tasks in shaders so they get the speed boost from the GPU. However, now I'm starting to realize that some things simply work better on the CPU and actually perform worse on the GPU (particularly when a geometry shader is involved). For example, in a recent project I did involving procedurally generated terrain, I tried passing a grid of single triangles into a geometry shader, and tesselated each of these triangles into quads with 400 vertices whose height was determined by a noise function. This worked fine, and looked great, but easily maxed out the GPU with only 25 base triangles and caused a very slow framerate. I then discovered that tesselating on the CPU instead, and setting the height (using noise function) in the vertex shader was actually faster! This prompted me to question the benefits of using the GPU as much as possible... So, I was wondering if someone could describe the general pros and cons of using the GPU vs CPU for intensive graphics tasks. I know this mainly comes down to what your trying to achieve, so if necessary, use the above scenario to discuss why the "CPU + vertex shader" was actually faster than doing everything in the geometry shader on the GPU. It's possible my hardware (newest macbook pro) isn't optomized well for the geometry shader (thus causing the slow framerate). Also, I read that the vertex shader is very good with parallelism, and would love a quick explanation of how this may have played a role in speeding up my procedural terrain. Any info/advice about CPU/GPU/shaders would be awesome!

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  • Solving Big Problems with Oracle R Enterprise, Part II

    - by dbayard
    Part II – Solving Big Problems with Oracle R Enterprise In the first post in this series (see https://blogs.oracle.com/R/entry/solving_big_problems_with_oracle), we showed how you can use R to perform historical rate of return calculations against investment data sourced from a spreadsheet.  We demonstrated the calculations against sample data for a small set of accounts.  While this worked fine, in the real-world the problem is much bigger because the amount of data is much bigger.  So much bigger that our approach in the previous post won’t scale to meet the real-world needs. From our previous post, here are the challenges we need to conquer: The actual data that needs to be used lives in a database, not in a spreadsheet The actual data is much, much bigger- too big to fit into the normal R memory space and too big to want to move across the network The overall process needs to run fast- much faster than a single processor The actual data needs to be kept secured- another reason to not want to move it from the database and across the network And the process of calculating the IRR needs to be integrated together with other database ETL activities, so that IRR’s can be calculated as part of the data warehouse refresh processes In this post, we will show how we moved from sample data environment to working with full-scale data.  This post is based on actual work we did for a financial services customer during a recent proof-of-concept. Getting started with the Database At this point, we have some sample data and our IRR function.  We were at a similar point in our customer proof-of-concept exercise- we had sample data but we did not have the full customer data yet.  So our database was empty.  But, this was easily rectified by leveraging the transparency features of Oracle R Enterprise (see https://blogs.oracle.com/R/entry/analyzing_big_data_using_the).  The following code shows how we took our sample data SimpleMWRRData and easily turned it into a new Oracle database table called IRR_DATA via ore.create().  The code also shows how we can access the database table IRR_DATA as if it was a normal R data.frame named IRR_DATA. If we go to sql*plus, we can also check out our new IRR_DATA table: At this point, we now have our sample data loaded in the database as a normal Oracle table called IRR_DATA.  So, we now proceeded to test our R function working with database data. As our first test, we retrieved the data from a single account from the IRR_DATA table, pull it into local R memory, then call our IRR function.  This worked.  No SQL coding required! Going from Crawling to Walking Now that we have shown using our R code with database-resident data for a single account, we wanted to experiment with doing this for multiple accounts.  In other words, we wanted to implement the split-apply-combine technique we discussed in our first post in this series.  Fortunately, Oracle R Enterprise provides a very scalable way to do this with a function called ore.groupApply().  You can read more about ore.groupApply() here: https://blogs.oracle.com/R/entry/analyzing_big_data_using_the1 Here is an example of how we ask ORE to take our IRR_DATA table in the database, split it by the ACCOUNT column, apply a function that calls our SimpleMWRR() calculation, and then combine the results. (If you are following along at home, be sure to have installed our myIRR package on your database server via  “R CMD INSTALL myIRR”). The interesting thing about ore.groupApply is that the calculation is not actually performed in my desktop R environment from which I am running.  What actually happens is that ore.groupApply uses the Oracle database to perform the work.  And the Oracle database is what actually splits the IRR_DATA table by ACCOUNT.  Then the Oracle database takes the data for each account and sends it to an embedded R engine running on the database server to apply our R function.  Then the Oracle database combines all the individual results from the calls to the R function. This is significant because now the embedded R engine only needs to deal with the data for a single account at a time.  Regardless of whether we have 20 accounts or 1 million accounts or more, the R engine that performs the calculation does not care.  Given that normal R has a finite amount of memory to hold data, the ore.groupApply approach overcomes the R memory scalability problem since we only need to fit the data from a single account in R memory (not all of the data for all of the accounts). Additionally, the IRR_DATA does not need to be sent from the database to my desktop R program.  Even though I am invoking ore.groupApply from my desktop R program, because the actual SimpleMWRR calculation is run by the embedded R engine on the database server, the IRR_DATA does not need to leave the database server- this is both a performance benefit because network transmission of large amounts of data take time and a security benefit because it is harder to protect private data once you start shipping around your intranet. Another benefit, which we will discuss in a few paragraphs, is the ability to leverage Oracle database parallelism to run these calculations for dozens of accounts at once. From Walking to Running ore.groupApply is rather nice, but it still has the drawback that I run this from a desktop R instance.  This is not ideal for integrating into typical operational processes like nightly data warehouse refreshes or monthly statement generation.  But, this is not an issue for ORE.  Oracle R Enterprise lets us run this from the database using regular SQL, which is easily integrated into standard operations.  That is extremely exciting and the way we actually did these calculations in the customer proof. As part of Oracle R Enterprise, it provides a SQL equivalent to ore.groupApply which it refers to as “rqGroupEval”.  To use rqGroupEval via SQL, there is a bit of simple setup needed.  Basically, the Oracle Database needs to know the structure of the input table and the grouping column, which we are able to define using the database’s pipeline table function mechanisms. Here is the setup script: At this point, our initial setup of rqGroupEval is done for the IRR_DATA table.  The next step is to define our R function to the database.  We do that via a call to ORE’s rqScriptCreate. Now we can test it.  The SQL you use to run rqGroupEval uses the Oracle database pipeline table function syntax.  The first argument to irr_dataGroupEval is a cursor defining our input.  You can add additional where clauses and subqueries to this cursor as appropriate.  The second argument is any additional inputs to the R function.  The third argument is the text of a dummy select statement.  The dummy select statement is used by the database to identify the columns and datatypes to expect the R function to return.  The fourth argument is the column of the input table to split/group by.  The final argument is the name of the R function as you defined it when you called rqScriptCreate(). The Real-World Results In our real customer proof-of-concept, we had more sophisticated calculation requirements than shown in this simplified blog example.  For instance, we had to perform the rate of return calculations for 5 separate time periods, so the R code was enhanced to do so.  In addition, some accounts needed a time-weighted rate of return to be calculated, so we extended our approach and added an R function to do that.  And finally, there were also a few more real-world data irregularities that we needed to account for, so we added logic to our R functions to deal with those exceptions.  For the full-scale customer test, we loaded the customer data onto a Half-Rack Exadata X2-2 Database Machine.  As our half-rack had 48 physical cores (and 96 threads if you consider hyperthreading), we wanted to take advantage of that CPU horsepower to speed up our calculations.  To do so with ORE, it is as simple as leveraging the Oracle Database Parallel Query features.  Let’s look at the SQL used in the customer proof: Notice that we use a parallel hint on the cursor that is the input to our rqGroupEval function.  That is all we need to do to enable Oracle to use parallel R engines. Here are a few screenshots of what this SQL looked like in the Real-Time SQL Monitor when we ran this during the proof of concept (hint: you might need to right-click on these images to be able to view the images full-screen to see the entire image): From the above, you can notice a few things (numbers 1 thru 5 below correspond with highlighted numbers on the images above.  You may need to right click on the above images and view the images full-screen to see the entire image): The SQL completed in 110 seconds (1.8minutes) We calculated rate of returns for 5 time periods for each of 911k accounts (the number of actual rows returned by the IRRSTAGEGROUPEVAL operation) We accessed 103m rows of detailed cash flow/market value data (the number of actual rows returned by the IRR_STAGE2 operation) We ran with 72 degrees of parallelism spread across 4 database servers Most of our 110seconds was spent in the “External Procedure call” event On average, we performed 8,200 executions of our R function per second (110s/911k accounts) On average, each execution was passed 110 rows of data (103m detail rows/911k accounts) On average, we did 41,000 single time period rate of return calculations per second (each of the 8,200 executions of our R function did rate of return calculations for 5 time periods) On average, we processed over 900,000 rows of database data in R per second (103m detail rows/110s) R + Oracle R Enterprise: Best of R + Best of Oracle Database This blog post series started by describing a real customer problem: how to perform a lot of calculations on a lot of data in a short period of time.  While standard R proved to be a very good fit for writing the necessary calculations, the challenge of working with a lot of data in a short period of time remained. This blog post series showed how Oracle R Enterprise enables R to be used in conjunction with the Oracle Database to overcome the data volume and performance issues (as well as simplifying the operations and security issues).  It also showed that we could calculate 5 time periods of rate of returns for almost a million individual accounts in less than 2 minutes. In a future post, we will take the same R function and show how Oracle R Connector for Hadoop can be used in the Hadoop world.  In that next post, instead of having our data in an Oracle database, our data will live in Hadoop and we will how to use the Oracle R Connector for Hadoop and other Oracle Big Data Connectors to move data between Hadoop, R, and the Oracle Database easily.

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  • OpenGL CPU vs. GPU

    - by Nitrex88
    So I've always been under the impression that doing work on the GPU is always faster than on the CPU. Because of this, in OpenGL, I usually try to do intensive tasks in shaders so they get the speed boost from the GPU. However, now I'm starting to realize that some things simply work better on the CPU and actually perform worse on the GPU (particularly when a geometry shader is involved). For example, in a recent project I did involving procedurally generated terrain, I tried passing a grid of single triangles into a geometry shader, and tesselated each of these triangles into quads with 400 vertices whose height was determined by a noise function. This worked fine, and looked great, but easily maxed out the GPU with only 25 base triangles and caused a very slow framerate. I then discovered that tesselating on the CPU instead, and setting the height (using noise function) in the vertex shader was actually faster! This prompted me to question the benefits of using the GPU as much as possible... So, I was wondering if someone could describe the general pros and cons of using the GPU vs CPU for intensive graphics tasks. I know this mainly comes down to what your trying to achieve, so if necessary, use the above scenario to discuss why the "CPU + vertex shader" was actually faster than doing everything in the geometry shader on the GPU. It's possible my hardware (newest macbook pro) isn't optomized well for the geometry shader (thus causing the slow framerate). Also, I read that the vertex shader is very good with parallelism, and would love a quick explanation of how this may have played a role in speeding up my procedural terrain. Any info/advice about CPU/GPU/shaders would be awesome!

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  • Dev Lead Job opening on my team

    My product unit (Parallel Developer Tools) is hiring a developer lead here in Redmond. This position is specifically on the debugger feature team that I "Program Manage".So, if you have what it takes and don't mind working with me every single day, click on the link below to read more and apply. You can also send me your resume and I'll make sure it gets to the right place and that you get a prompt response.There is a very long job description on the Microsoft careers site under job id 707388.Here is an excerpt from the middle (emphasis mine):"...We are in search of a talented and innovative senior lead software design engineer to own development of the debugging tools for data parallelism (including GP-GPU) and HPC Clusters being built by our team.To be successful, you need to be able to guide careers, design and architect well, communicate and share the best development practices, collaborate with your peers, contribute to the vision, and code significant portions of the solution. We want to hear from you if you're passionate about making your mark in the parallel development space, improving people, and building world-class tools."Responsibilities include:Managing a team of senior and junior developersDesign and coding high-quality software..."For the full background story, requirements, qualifications and responsibilities please visit the official page. Comments about this post welcome at the original blog.

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  • HttpClient multithread performance

    - by pepper
    I have an application which downloads more than 4500 html pages from 62 target hosts using HttpClient (4.1.3 or 4.2-beta). It runs on Windows 7 64-bit. Processor - Core i7 2600K. Network bandwidth - 54 Mb/s. At this moment it uses such parameters: DefaultHttpClient and PoolingClientConnectionManager; Also it hasIdleConnectionMonitorThread from http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html; Maximum total connections = 80; Default maximum connections per route = 5; For thread management it uses ForkJoinPool with the parallelism level = 5 (Do I understand correctly that it is a number of working threads?) In this case my network usage (in Windows task manager) does not rise above 2.5%. To download 4500 pages it takes 70 minutes. And in HttpClient logs I have such things: DEBUG ForkJoinPool-2-worker-1 [org.apache.http.impl.conn.PoolingClientConnectionManager]: Connection released: [id: 209][route: {}-http://stackoverflow.com][total kept alive: 6; route allocated: 1 of 5; total allocated: 10 of 80] Total allocated connections do not raise above 10-12, in spite of that I've set it up to 80 connections. If I'll try to rise parallelism level to 20 or 80, network usage remains the same but a lot connection time-outs will be generated. I've read tutorials on hc.apache.org (HttpClient Performance Optimization Guide and HttpClient Threading Guide) but they does not help. Task's code looks like this: public class ContentDownloader extends RecursiveAction { private final HttpClient httpClient; private final HttpContext context; private List<Entry> entries; public ContentDownloader(HttpClient httpClient, List<Entry> entries){ this.httpClient = httpClient; context = new BasicHttpContext(); this.entries = entries; } private void computeDirectly(Entry entry){ final HttpGet get = new HttpGet(entry.getLink()); try { HttpResponse response = httpClient.execute(get, context); int statusCode = response.getStatusLine().getStatusCode(); if ( (statusCode >= 400) && (statusCode <= 600) ) { logger.error("Couldn't get content from " + get.getURI().toString() + "\n" + response.toString()); } else { HttpEntity entity = response.getEntity(); if (entity != null) { String htmlContent = EntityUtils.toString(entity).trim(); entry.setHtml(htmlContent); EntityUtils.consumeQuietly(entity); } } } catch (Exception e) { } finally { get.releaseConnection(); } } @Override protected void compute() { if (entries.size() <= 1){ computeDirectly(entries.get(0)); return; } int split = entries.size() / 2; invokeAll(new ContentDownloader(httpClient, entries.subList(0, split)), new ContentDownloader(httpClient, entries.subList(split, entries.size()))); } } And the question is - what is the best practice to use multi threaded HttpClient, may be there is a some rules for setting up ConnectionManager and HttpClient? How can I use all of 80 connections and raise network usage? If necessary, I will provide more code.

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  • Generalist Languages: Dying or Alive and Well?

    - by dsimcha
    Around here, it seems like there's somewhat of a consensus that generalist programming languages (that try to be good at everything, support multiple paradigms, support both very high- and very low-level programming), etc. are a bad idea, and that it's better to pick the right tool for the job and use lots of different languages. I see three major areas where this is flawed: Interfacing multiple languages is always at least a source of friction and is sometimes practically impossible. How severe a problem this is depends on how fine-grained the interfacing is. Near the boundary between the two languages, though, you're basically limited to the intersection of their features, and you have to care about things like binary interfaces that you usually wouldn't. Passing complex data structures (i.e. not just primitives and arrays of primitives) between languages is almost always a hassle. Furthermore, shifting between different syntaxes, different conventions, etc. can be confusing and annoying, though this is a fairly minor complaint. Requirements are never set in stone. I hate picking a language thinking it's the right tool for the job, then realizing that, when some new requirement surfaces, it's actually a terrible choice for that requirement. This has happened to me several times before, usually when working with languages that are very slow, very domain specific and/or has very poor concurrency/parallelism support. When you program in a language for a while, you start to build up a personal toolbox of small utility functions/classes/programs. The value of these goes drastically down if you're forced to use a different language than the one you've accumulated all this code in. What am I missing here? Why shouldn't more focus be placed on generalist languages? Are generalist languages as a category dying or alive and well?

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  • Parallelize incremental processing in Tabular #ssas #tabular

    - by Marco Russo (SQLBI)
    I recently came in a problem trying to improve the parallelism of Tabular processing. As you know, multiple tables can be processed in parallel, whereas the processing of several partitions within the same table cannot be parallelized. When you perform an incremental update by adding only new rows to existing table, what you really do is adding rows to a partition, so adding rows to many tables means adding rows to several partitions. The particular condition you have in this case is that every partition in which you add rows belongs to a different table. Adding rows implies using the ProcessAdd command; its QueryBinding parameter specifies a SQL syntax to read new rows, otherwise the original query specified for the partition will be used, and it could generate duplicated data if you don’t have a dynamic behavior on the SQL side. If you create the required XMLA code manually, you will find that the QueryBinding node that should be part of the ProcessAdd command has to be moved out from ProcessAdd in case you are using a Batch command with more than one Process command (which is the reason why you want to use a single batch: run multiple process operations in parallel!). If you use AMO (Analysis Management Objects) you will find that this combination is not supported, even if you don’t have a syntax error compiling the code, but you might obtain this error at execution time: The syntax for the 'Process' command is incorrect. The 'Bindings' keyword cannot appear under a 'Process' command if the 'Process' command is a part of a 'Batch' command and there are more than one 'Process' commands in the 'Batch' or the 'Batch' command contains any out of line related information. In this case, the 'Bindings' keyword should be a part of the 'Batch' command only. If this is happening to you, the best solution I’ve found is manipulating the XMLA code generated by AMO moving the Binding nodes in the right place. A more detailed description of the issue and the code required to send a correct XMLA batch to Analysis Services is available in my article Parallelize ProcessAdd with AMO. By the way, the same technique (and code) can be used also if you have the same problem in a Multidimensional model.

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  • Oracle R Distribution 2-13.2 Update Available

    - by Sherry LaMonica
    Oracle has released an update to the Oracle R Distribution, an Oracle-supported distribution of open source R. Oracle R Distribution 2-13.2 now contains the ability to dynamically link the following libraries on both Windows and Linux: The Intel Math Kernel Library (MKL) on Intel chips The AMD Core Math Library (ACML) on AMD chips To take advantage of the performance enhancements provided by Intel MKL or AMD ACML in Oracle R Distribution, simply add the MKL or ACML shared library directory to the LD_LIBRARY_PATH system environment variable. This automatically enables MKL or ACML to make use of all available processors, vastly speeding up linear algebra computations and eliminating the need to recompile R.  Even on a single core, the optimized algorithms in the Intel MKL libraries are faster than using R's standard BLAS library. Open-source R is linked to NetLib's BLAS libraries, but they are not multi-threaded and only use one core. While R's internal BLAS are efficient for most computations, it's possible to recompile R to link to a different, multi-threaded BLAS library to improve performance on eligible calculations. Compiling and linking to R yourself can be involved, but for many, the significantly improved calculation speed justifies the effort. Oracle R Distribution notably simplifies the process of using external math libraries by enabling R to auto-load MKL or ACML. For R commands that don't link to BLAS code, taking advantage of database parallelism using embedded R execution in Oracle R Enterprise is the route to improved performance. For more information about rebuilding R with different BLAS libraries, see the linear algebra section in the R Installation and Administration manual. As always, the Oracle R Distribution is available as a free download to anyone. Questions and comments are welcome on the Oracle R Forum.

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  • SQL Saturday #220 Atlanta May 2013!

    - by Most Valuable Yak (Rob Volk)
    If you love SQL Server training and are near the Atlanta area, or just love us so much you're willing to travel here, please come join us for: SQL SATURDAY #220! The main event is Saturday, May 18.  The event is free, with a $10.00 lunch fee.  The main page has more details here: http://www.sqlsaturday.com/220/eventhome.aspx We are also offering pre-conference sessions on Friday, May 17, by 5 world-renowned presenters: Denny Cherry: SQL Server Security Register! Site Twitter Adam Machanic: Surfing the Multicore Wave: Processors, Parallelism, and Performance Register! Site Twitter Stacia Misner: Languages of BI Register! Site Twitter Bill Pearson: Practical Self-Service BI with PowerPivot for Excel Register! Site Twitter Eddie Wuerch: The DBA Skills Upgrade Toolkit Register! Site Twitter         We have an early bird registration price of $119 until noon EST Friday, March 22.  After that the price goes to $149, a STEAL when you compare it to the PASS Summit price. :) Please click on the links to register and for more information.  You can also follow the hash tag #SQLSatATL on Twitter for more news about this event. Can't wait to see you all there!

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  • TXPAUSE : polite waiting for hardware transactional memory

    - by Dave
    Classic locks are an appropriate tool to prevent potentially conflicting operations A and B, invoked by different threads, from running at the same time. In a sense the locks cause either A to run before B or vice-versa. Similarly, we can replace the locks with hardware transactional memory, or use transactional lock elision to leverage potential disjoint access parallelism between A and B. But often we want A to wait until B has run. In a Pthreads environment we'd usually use locks in conjunction with condition variables to implement our "wait until" constraint. MONITOR-MWAIT is another way to wait for a memory location to change, but it only allows us to track one cache line and it's only available on x86. There's no similar "wait until" construct for hardware transactions. At the instruction-set level a simple way to express "wait until" in transactions would be to add a new TXPAUSE instruction that could be used within an active hardware transaction. TXPAUSE would politely stall the invoking thread, possibly surrendering or yielding compute resources, while at the same time continuing to track the transaction's address-set. Once a transaction has executed TXPAUSE it can only abort. Ideally that'd happen when some other thread modifies a variable that's in the transaction's read-set or write-set. And since we're aborting all writes would be discarded. In a sense this gives us multi-location MWAIT but with much more flexibility. We could also augment the TXPAUSE with a cycle-count bound to cap the time spent stalled. I should note that we can already enter a tight spin loop in a transaction to wait for updates to address-set to cause an abort. Assuming that the implementation monitors the address-set via cache-coherence probes, by waiting in this fashion we actually communicate via the probes, and not via memory values. That is the updating thread signals the waiter via probes instead of by traditional memory values. But TXPAUSE gives us a polite way to spin.

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  • Should I use OpenGL or DX11 for my game?

    - by Sundareswaran Senthilvel
    I'm planning to write a game from scratch (a BIG Game, for commercial purpose). I'm aware that there are certain compute libraries like OpenCL, AMD APP SDK, C++ AMP as well as DirectCompute - both from MS (NOT interested in CUDA) are available in the market. I'm planning to write the game from the scratch, which includes the following engines... Physics Engine AI Engine Main Game Engine (... and if anything is missed). I'm aware that, there are some free physics engine libraries in the market. Not sure about free AI engine libraries. I'm bit confused in choosing between the OpenCL, AMD APP SDK, and C++ AMP libraries (as already mentioned i'm NOT interested in CUDA). I want my game to be published in Windows/Android/Mac OSX. It means it should be a cross-platform game. I will be having "one source code" that i'll compile for various platforms like Windows/Android/Mac OSX, and any others if i missed. Note: Since I'm NOT a Java guy, kindly do NOT suggest me the Java Language. For Graphics language should i use OpenGL or DirectX 11? I have heard that OpenGL runs on a single core, and not sure of DirectX 11. Between OpenGL and DirectX which one should i follow? or else, are there any other graphics language that i need to start with? I want to make use of the parallelism in GPU as well as CPU.

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  • Game Development

    - by Sundareswaran Senthilvel
    I'm planning to write a game from scratch (a BIG Game, for commercial purpose). I'm aware that there are certain compute libraries like OpenCL, AMD APP SDK, C++ AMP as well as DirectCompute - both from MS (NOT interested in CUDA) are available in the market. I'm planning to write the game from the scratch, which includes the following engines... 1.Physics Engine 2.AI Engine 3.Main Game Engine (... and if anything is missed). I'm aware that, there are some free physics engine libraries in the market. Not sure about free AI engine libraries. I'm bit confused in choosing between the OpenCL, AMD APP SDK, and C++ AMP libraries (as already mentioned i'm NOT interested in CUDA). I want my game to be published in Windows/Android/Mac OSX. It means it should be a cross-platform game. I will be having "one source code" that i'll compile for various platforms like Windows/Android/Mac OSX, and any others if i missed. Note: Since I'm NOT a Java guy, kindly do NOT suggest me the Java Language. For Graphics language should i use OpenGL or DirectX 11? I have heard that OpenGL runs on a single core, and not sure of DirectX 11. Between OpenGL and DirectX which one should i follow? or else, are there any other graphics language that i need to start with? I want to make use of the parallelism in GPU as well as CPU.

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  • CodePlex Daily Summary for Saturday, January 29, 2011

    CodePlex Daily Summary for Saturday, January 29, 2011Popular ReleasesRawr: Rawr 4.0.17 Beta: Rawr is now web-based. The link to use Rawr4 is: http://elitistjerks.com/rawr.phpThis is the Cataclysm Beta Release. More details can be found at the following link http://rawr.codeplex.com/Thread/View.aspx?ThreadId=237262 and on the Version Notes page: http://rawr.codeplex.com/wikipage?title=VersionNotes As of the 4.0.16 release, you can now also begin using the new Downloadable WPF version of Rawr!This is a pre-alpha release of the WPF version, there are likely to be a lot of issues. If you...VivoSocial: VivoSocial 7.4.2: Version 7.4.2 of VivoSocial has been released. If you experienced any issues with the previous version, please update your modules to the 7.4.2 release and see if they persist. If you have any questions about this release, please post them in our Support forums. If you are experiencing a bug or would like to request a new feature, please submit it to our issue tracker. Web Controls * Updated Business Objects and added a new SQL Data Provider File. Groups * Fixed a security issue whe...PHP Manager for IIS: PHP Manager 1.1.1 for IIS 7: This is a minor release of PHP Manager for IIS 7. It contains all the functionality available in 56962 plus several bug fixes (see change list for more details). Also, this release includes Russian language support. SHA1 codes for the downloads are: PHPManagerForIIS-1.1.0-x86.msi - 6570B4A8AC8B5B776171C2BA0572C190F0900DE2 PHPManagerForIIS-1.1.0-x64.msi - 12EDE004EFEE57282EF11A8BAD1DC1ADFD66A654BloodSim: WControls.dll update: Priority Update It's just come to my attention that the latest version of WControls.dll was not included in the 1.4 release and as a result, BloodSim has been unuseable. Please download WControls.dll from here, and this will rectify the issue.VFPX: VFP2C32 2.0.0.8 Release Candidate: This release includes several bugfixes, new functions and finally a CHM help file for the complete library.DB>doc for Microsoft SQL Server: 1.0.0.0: Initial release Supported output HTML WikiPlex markup Raw XML Supported objects Tables Primary Keys Foreign Keys ViewsmojoPortal: 2.3.6.1: see release notes on mojoportal.com http://www.mojoportal.com/mojoportal-2361-released.aspx Note that we have separate deployment packages for .NET 3.5 and .NET 4.0 The deployment package downloads on this page are pre-compiled and ready for production deployment, they contain no C# source code. To download the source code see the Source Code Tab I recommend getting the latest source code using TortoiseHG, you can get the source code corresponding to this release here.Office Web.UI: Alpha preview: This is the first alpha release. Very exciting moment... This download is just the demo application : "Contoso backoffice Web App". No source included for the moment, just the app, for testing purposes and for feedbacks !! This package includes a set of official MS Office icons (143 png 16x16 and 132 png 32x32) to really make a great app ! Please rate and give feedback ThanksParallel Programming with Microsoft Visual C++: Drop 6 - Chapters 4 and 5: This is Drop 6. It includes: Drafts of the Preface, Introduction, Chapters 2-7, Appendix B & C and the glossary Sample code for chapters 2-7 and Appendix A & B. The new material we'd like feedback on is: Chapter 4 - Parallel Aggregation Chapter 5 - Futures The source code requires Visual Studio 2010 in order to run. There is a known bug in the A-Dash sample when the user attempts to cancel a parallel calculation. We are working to fix this.Catel - WPF and Silverlight MVVM library: 1.1: (+) Styles can now be changed dynamically, see Examples application for a how-to (+) ViewModelBase class now have a constructor that allows services injection (+) ViewModelBase services can now be configured by IoC (via Microsoft.Unity) (+) All ViewModelBase services now have a unit test implementation (+) Added IProcessService to run processes from a viewmodel with directly using the process class (which makes it easier to unit test view models) (*) If the HasErrors property of DataObjec...NodeXL: Network Overview, Discovery and Exploration for Excel: NodeXL Excel Template, version 1.0.1.160: The NodeXL Excel template displays a network graph using edge and vertex lists stored in an Excel 2007 or Excel 2010 workbook. What's NewThis release improves NodeXL's Twitter and Pajek features. See the Complete NodeXL Release History for details. Installation StepsFollow these steps to install and use the template: Download the Zip file. Unzip it into any folder. Use WinZip or a similar program, or just right-click the Zip file in Windows Explorer and select "Extract All." Close Ex...Kooboo CMS: Kooboo CMS 3.0 CTP: Files in this downloadkooboo_CMS.zip: The kooboo application files Content_DBProvider.zip: Additional content database implementation of MSSQL, RavenDB and SQLCE. Default is XML based database. To use them, copy the related dlls into web root bin folder and remove old content provider dlls. Content provider has the name like "Kooboo.CMS.Content.Persistence.SQLServer.dll" View_Engines.zip: Supports of Razor, webform and NVelocity view engine. Copy the dlls into web root bin folder to enable...UOB & ME: UOB ME 2.6: UOB ME 2.6????: ???? V1.0: ???? V1.0 ??Password Generator: 2.2: Parallel password generation Password strength calculation ( Same method used by Microsoft here : https://www.microsoft.com/protect/fraud/passwords/checker.aspx ) Minor code refactoringVisual Studio 2010 Architecture Tooling Guidance: Spanish - Architecture Guidance: Francisco Fagas http://geeks.ms/blogs/ffagas, Microsoft Most Valuable Professional (MVP), localized the Visual Studio 2010 Quick Reference Guidance for the Spanish communities, based on http://vsarchitectureguide.codeplex.com/releases/view/47828. Release Notes The guidance is available in a xps-only (default) or complete package. The complete package contains the files in xps, pdf and Office 2007 formats. 2011-01-24 Publish version 1.0 of the Spanish localized bits.ASP.NET MVC Project Awesome, jQuery Ajax helpers (controls): 1.6.2: A rich set of helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager the html generation has been optimized, the html page size is much smaller nowFacebook Graph Toolkit: Facebook Graph Toolkit 0.6: new Facebook Graph objects: Application, Page, Post, Comment Improved Intellisense documentation new Graph Api connections: albums, photos, posts, feed, home, friends JSON Toolkit upgraded to version 0.9 (beta release) with bug fixes and new features bug fixed: error when handling empty JSON arrays bug fixed: error when handling JSON array with square or large brackets in the message bug fixed: error when handling JSON obejcts with double quotation in the message bug fixed: erro...Microsoft All-In-One Code Framework: Visual Studio 2008 Code Samples 2011-01-23: Code samples for Visual Studio 2008MVVM Light Toolkit: MVVM Light Toolkit V3 SP1 (3): Instructions for installation: http://www.galasoft.ch/mvvm/installing/manually/ Includes the hotfix templates for Windows Phone 7 development. This is only relevant if you didn't already install the hotfix described at http://blog.galasoft.ch/archive/2010/07/22/mvvm-light-hotfix-for-windows-phone-7-developer-tools-beta.aspx.New ProjectsAsp.Net MvcRoute Debugger Visualizer: Asp.Net MvcRoute Debugger Visualizer is an extension for Visual Studio 2010.It displays the matched route data and datatokens of all defined routes in your mvc applicationAutoLaunch for Windows Embedded Compact (CE): AutoLaunch component for Windows Embedded CE 6.0 and Windows Embedded Compact 7BicubicResizeSilverlight: A client-side Silverlight library for performing a bicubic resize. Cloud Monitoring Studio: Cloud Monitoring Studio provides real-time performance monitoring mechanism for Azure deployed applications/Azure roles with the help of easy-to-understand graphs. Users can configure required performance counters for individual Azure roles through easy-to-use & intuitive GUI.CoreCon for Windows Embedded Compact (CE): CoreCon component for Windows Embedded CE 6.0 and Windows Embedded Compact 7, to simplify the tasks needed to include CoreCon files to the OS image.DokanDiscUtils Bridge: This a a bridge for the Dokan library and the DiscUtils library that allows Any partition/image that discutils can open to be mounted using dokanEverything About My Share: Everything About My ShareExtraordinary Ideas: This project contains some Extra oradinary solutions for difficult software problems.. Article's are in Turkish Language tahircakmak.blogspot.comIE9 Helper: The IE9 Helper is an ASP.NET Helper to makes adding IE9 features simple.ITSolutions: .NET Sandbox SolutionsKitty - Async Server: Kitty is an Async Server with C# and Java versions. It builds on Parallelism to deliver a Internet Scale Server StarterKit.mediainfocollector: Retrieves info from mediafilesMini - Async WebSocket Server: Mini is an Async WebSocket Server with versions in C# and Java. It builds on Parallelism and Kitty to deliver an Internet Scale WebSocket Server StarterKit. MVC N-tier EMR Sample Application: This sample uses EMR to showcase a MVC N-Tier application. It uses WCF to separate the presentation from the DB/Backend.MyPhotoGallery: MyPhotoGallery is a photo gallery developed in ASP.Net MVC.NuGet: NuGet is a free, open source developer focused package management system for the .NET platform intent on simplifying the process of incorporating third party libraries into a .NET application during development.OneCode CodeBox: OneCode CodeBoxonecode toolkit: toolsOrchard SSL: Orchard Secured Sockets Layer (SSL) adds new features to force the usage of SSL in sections like authentication pages or the dashboard.OrchardCMS - Lokalizacija: OrchardCMS - Lokalizacija je projekat lokalizacije Orchard CMS-a na srpski, hrvatski, srpskohrvatski, hrvatskosrpski i sve ostale jezike sa podrucija ex-YU. Pokušacemo da iskorisitmo slicnosti u jezicima kako bi jedni drugima pomogli i olakšali lokalizaciju Orchard-a. Pyxis Install Maker: This utility creates single file installs for Pyxis 2 applications.SaleCard: TestSharePoint Social Networking: A Collection of solutions aimed at adding social network to your SharePoint 2010 site. The collection will include web parts, ribbon extensions and other type of solutions that will add or enhance the social networking capabilities of SharePoint. The solution is written in c#.SmartScreenTerminator: Pissed off by the stupid "smart screen" asking you to "remember to protect your password" every time you click someone else's blog link in your Windows Live homepage? Use this three line appication to allow your IE to automatically navigate to the destination page.StreetScene: StreetScene is a sample project showing how to use Microsoft technologies such as ASP.NET, Azure and Silverlight to build rich applications.svmnetx: testtest_project: test projectTweet-Links: Tweet-Links is designed for ultra-fast sending a twitter selected text and files and images.WCMF - Windows Content Management Framework: WCMF is a framework that allows one to build CMS appllications that target the Windows platform (whereas a typical CMS system is usually web based). Used technologies are MEF, WCF, WPF (including Silverlight) and Caliburn.Micro.WebNoteAOP: A sample project for aspect oriented programming with PostSharp. The main purpose is a short introduction. All aspects are made in a very simple way. They should be useful for simple applications. Please keep in mind, that complex problems often require a complex solution, too.

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  • Is there a way to ‘join’ (block) in POSIX threads, without exiting the joinee?

    - by elliottcable
    I’m buried in multithreading / parallelism documents, trying to figure out how to implement a threading implementation in a programming language I’ve been designing. I’m trying to map a mental model to the pthreads.h library, but I’m having trouble with one thing: I need my interpreter instances to continue to exist after they complete interpretation of a routine (the language’s closure/function data type), because I want to later assign other routines to them for interpretation, thus saving me the thread and interpreter setup/teardown time. This would be fine, except that pthread_join(3) requires that I call pthread_exit(3) to ‘unblock’ the original thread. How can I block the original thread (when it needs the result of executing the routine), and then unblock it when interpretation of the child routine is complete?

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  • PLINQ delayed execution

    - by tbischel
    I'm trying to understand how parallelism might work using PLINQ, given delayed execution. Here is a simple example. string[] words = { "believe", "receipt", "relief", "field" }; bool result = words.AsParallel().Any(w => w.Contains("ei")); With LINQ, I would expect the execution to reach the "receipt" value and return true, without executing the query for rest of the values. If we do this in parallel, the evaluation of "relief" may have began before the result of "receipt" has returned. But once the query knows that "receipt" will cause a true result, will the other threads yield immediately? In my case, this is important because the "any" test may be very expensive, and I would want to free up the processors for execution of other tasks.

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