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  • Would this method work to scale out SQL queries?

    - by David
    I have a database containing a single huge table. At the moment a query can take anything from 10 to 20 minutes and I need that to go down to 10 seconds. I have spent months trying different products like GridSQL. GridSQL works fine, but is using its own parser which does not have all the needed features. I have also optimized my database in various ways without getting the speedup I need. I have a theory on how one could scale out queries, meaning that I utilize several nodes to run a single query in parallel. The idea is to take an incoming SQL query and simply run it exactly like it is on all the nodes. When the results are returned to a coordinator node, the same query is run on the union of the resultsets. I realize that an aggregate function like average need to be rewritten into a count and sum to the nodes and that the coordinator divides the sum of the sums with the sum of the counts to get the average. What kinds of problems could not easily be solved using this model. I believe one issue would be the count distinct function. Edit: I am getting so many nice suggestions, but none have addressed the method.

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  • Parallel Computing Platform Developer Lab

    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...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • White Paper on Parallel Processing

    - by Andrew Kelly
      I just ran across what I think is a newly published white paper on parallel  processing in SQL Server 2008 R2. The date is October 2010 but this is the first time I have seen it so I am not 100% sure how new it really is. Maybe you have seen it already but if not I recommend taking a look. So far I haven’t had time to read it extensively but from a cursory look it appears to be quite informative and this is one of the areas least understood by a lot of dba’s. It was authored by Don Pinto...(read more)

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  • BPM Parallel Multi Instance sub processes by Niall Commiskey

    - by JuergenKress
    Here is a very simple scenario: An order with lines is processed. The OrderProcess accepts in an order with its attendant lines. The Fulfillment process is called for each order line. We do not have many order lines, and the processing is simple, so we run this in parallel. Let's look at the definition of the Multi Instance sub-process - Read the full article here. SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: BPM,Niall Commiskey,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • Looking for parallel programming problem

    - by Chris Lieb
    I am trying to come up with a problem that is easily solvable in a parallel manner and that requires communication between threads for a test. I also am trying to avoid problems that require require random waits, which rules out dining philosophers and producer-consumer (bounded buffer), two of the classics. My goal is for the student to be able to write the program in less than 20-30 minutes in front of a computer not knowing of the problem beforehand. (This is to prevent preparation more than to come up with something novel.) I am trying to stress the communication aspect of the program, though the multi-threaded nature is also important. Does anyone have some ideas? Edit: I'm using Google Go for the language and testing comprehension of the goroutines/channels combo vs an actors library that I authored.

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  • Optimum Number of Parallel Processes

    - by System Down
    I just finished coding a (basic) ray tracer in C# for fun and for the learning experience. Now I want to further that learning experience. It seems to me that ray tracing is a prime candidate for parallel processing, which is something I have very little experience in. My question is this: how do I know the optimum number of concurrent processes to run? My first instinct tells me: it depends on how many cores my processor has, but like I said I'm new to this and I may be neglecting something.

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  • Parallel Threading in Multi-Language Software?

    - by Smarty Twiti
    I'm developing a software that contain many modules/Daemon running in parallel manner, what i'm looking for is how to implement that, i cannot use Thread because some of those modules/Daemon are perhaps implemented in other languages (C,java,C#...). For example I'm using C for Hooking Messages exchanged between Windows kernel and top level applications, Java/C# to use some free library to simply parse XML(for example) or to accept and execute commands over the network..this can be done by C Language but just to improve productivity... Finally for GUI I'm using Ultimate++ (c++) that is like the main process that call and monitor(activate/deactivate/get state) of all other modules/Daemon through an interface. I admit that the development of each module/Daemon in a separate language greatly facilitates maintenance, but especially I am obliged to do that.. What is the best practice way to do that ? All helps will be appreciated.

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  • Parallel LINQ - PLINQ

    - by nmarun
    Turns out now with .net 4.0 we can run a query like a multi-threaded application. Say you want to query a collection of objects and return only those that meet certain conditions. Until now, we basically had one ‘control’ that iterated over all the objects in the collection, checked the condition on each object and returned if it passed. We obviously agree that if we can ‘break’ this task into smaller ones, assign each task to a different ‘control’ and ask all the controls to do their job - in-parallel, the time taken the finish the entire task will be much lower. Welcome to PLINQ. Let’s take some examples. I have the following method that uses our good ol’ LINQ. 1: private static void Linq(int lowerLimit, int upperLimit) 2: { 3: // populate an array with int values from lowerLimit to the upperLimit 4: var source = Enumerable.Range(lowerLimit, upperLimit); 5:  6: // Start a timer 7: Stopwatch stopwatch = new Stopwatch(); 8: stopwatch.Start(); 9:  10: // set the expectation => build the expression tree 11: var evenNumbers =   from num in source 12: where IsDivisibleBy(num, 2) 13: select num; 14: 15: // iterate over and print the returned items 16: foreach (var number in evenNumbers) 17: { 18: Console.WriteLine(string.Format("** {0}", number)); 19: } 20:  21: stopwatch.Stop(); 22:  23: // check the metrics 24: Console.WriteLine(String.Format("Elapsed {0}ms", stopwatch.ElapsedMilliseconds)); 25: } I’ve added comments for the major steps, but the only thing I want to talk about here is the IsDivisibleBy() method. I know I could have just included the logic directly in the where clause. I called a method to add ‘delay’ to the execution of the query - to simulate a loooooooooong operation (will be easier to compare the results). 1: private static bool IsDivisibleBy(int number, int divisor) 2: { 3: // iterate over some database query 4: // to add time to the execution of this method; 5: // the TableB has around 10 records 6: for (int i = 0; i < 10; i++) 7: { 8: DataClasses1DataContext dataContext = new DataClasses1DataContext(); 9: var query = from b in dataContext.TableBs select b; 10: 11: foreach (var row in query) 12: { 13: // Do NOTHING (wish my job was like this) 14: } 15: } 16:  17: return number % divisor == 0; 18: } Now, let’s look at how to modify this to PLINQ. 1: private static void Plinq(int lowerLimit, int upperLimit) 2: { 3: // populate an array with int values from lowerLimit to the upperLimit 4: var source = Enumerable.Range(lowerLimit, upperLimit); 5:  6: // Start a timer 7: Stopwatch stopwatch = new Stopwatch(); 8: stopwatch.Start(); 9:  10: // set the expectation => build the expression tree 11: var evenNumbers = from num in source.AsParallel() 12: where IsDivisibleBy(num, 2) 13: select num; 14:  15: // iterate over and print the returned items 16: foreach (var number in evenNumbers) 17: { 18: Console.WriteLine(string.Format("** {0}", number)); 19: } 20:  21: stopwatch.Stop(); 22:  23: // check the metrics 24: Console.WriteLine(String.Format("Elapsed {0}ms", stopwatch.ElapsedMilliseconds)); 25: } That’s it, this is now in PLINQ format. Oh and if you haven’t found the difference, look line 11 a little more closely. You’ll see an extension method ‘AsParallel()’ added to the ‘source’ variable. Couldn’t be more simpler right? So this is going to improve the performance for us. Let’s test it. So in my Main method of the Console application that I’m working on, I make a call to both. 1: static void Main(string[] args) 2: { 3: // set lower and upper limits 4: int lowerLimit = 1; 5: int upperLimit = 20; 6: // call the methods 7: Console.WriteLine("Calling Linq() method"); 8: Linq(lowerLimit, upperLimit); 9: 10: Console.WriteLine(); 11: Console.WriteLine("Calling Plinq() method"); 12: Plinq(lowerLimit, upperLimit); 13:  14: Console.ReadLine(); // just so I get enough time to read the output 15: } YMMV, but here are the results that I got:    It’s quite obvious from the above results that the Plinq() method is taking considerably less time than the Linq() version. I’m sure you’ve already noticed that the output of the Plinq() method is not in order. That’s because, each of the ‘control’s we sent to fetch the results, reported with values as and when they obtained them. This is something about parallel LINQ that one needs to remember – the collection cannot be guaranteed to be undisturbed. This could be counted as a negative about PLINQ (emphasize ‘could’). Nevertheless, if we want the collection to be sorted, we can use a SortedSet (.net 4.0) or build our own custom ‘sorter’. Either way we go, there’s a good chance we’ll end up with a better performance using PLINQ. And there’s another negative of PLINQ (depending on how you see it). This is regarding the CPU cycles. See the usage for Linq() method (used ResourceMonitor): I have dual CPU’s and see the height of the peak in the bottom two blocks and now compare to what happens when I run the Plinq() method. The difference is obvious. Higher usage, but for a shorter duration (width of the peak). Both these points make sense in both cases. Linq() runs for a longer time, but uses less resources whereas Plinq() runs for a shorter time and consumes more resources. Even after knowing all these, I’m still inclined towards PLINQ. PLINQ rocks! (no hard feelings LINQ)

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  • Consecutive verse Parallel Nunit Testing

    - by Jacobm001
    My office has roughly ~300 webpages that should be tested on a fairly regular basis. I'm working with Nunit, Selenium, and C# in Visual Studio 2010. I used this framework as a basis, and I do have a few working tests. The problem I'm running into is is that when I run the entire suite. In each run, a random test(s) will fail. If they're run individually, they will all pass. My guess is that Nunit is trying to run all 7 tests at the same time and the browser can't support this for obvious reasons. Watching the browser visually, this does seem to be the case. Looking at the screenshot below, I need to figure out a way in which the tests under Index_Tests are run sequentially, not in parallel. errors: Selenium2.OfficeClass.Tests.Index_Tests.index_4: OpenQA.Selenium.NoSuchElementException : Unable to locate element: "method":"id","selector":"textSelectorName"} Selenium2.OfficeClass.Tests.Index_Tests.index_7: OpenQA.Selenium.NoSuchElementException : Unable to locate element: "method":"id","selector":"textSelectorName"} example with one test: using OpenQA.Selenium; using NUnit.Framework; namespace Selenium2.OfficeClass.Tests { [TestFixture] public class Index_Tests : TestBase { public IWebDriver driver; [TestFixtureSetUp] public void TestFixtureSetUp() { driver = StartBrowser(); } [TestFixtureTearDown] public void TestFixtureTearDown() { driver.Quit(); } [Test] public void index_1() { OfficeClass index = new OfficeClass(driver); index.Navigate("http://url_goeshere"); index.SendKeyID("txtFiscalYear", "input"); index.SendKeyID("txtIndex", ""); index.SendKeyID("txtActivity", "input"); index.ClickID("btnDisplay"); } } }

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  • C++ Parallel Asynchonous task

    - by Doodlemeat
    I am currently building a randomly generated terrain game where terrain is created automatically around the player. I am experiencing lag when the generated process is active, as I am running quite heavy tasks with post-processing and creating physics bodies. Then I came to mind using a parallel asynchronous task to do the post-processing for me. But I have no idea how I am going to do that. I have searched for C++ std::async but I believe that is not what I want. In the examples I found, a task returned something. I want the task to change objects in the main program. This is what I want: // Main program // Chunks that needs to be processed. // NOTE! These chunks are already generated, but need post-processing only! std::vector<Chunk*> unprocessedChunks; And then my task could look something like this, running like a loop constantly checking if there is chunks to process. // Asynced task if(unprocessedChunks.size() > 0) { processChunk(unprocessedChunks.pop()); } I know it's not far from easy as I wrote it, but it would be a huge help for me if you could push me at the right direction. In Java, I could type something like this: asynced_task = startAsyncTask(new PostProcessTask()); And that task would run until I do this: asynced_task.cancel();

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  • Is it possible to distribute STDIN over parallel processes?

    - by Erik
    Given the following example input on STDIN: foo bar bar baz === qux bla === def zzz yyy Is it possible to split it on the delimiter (in this case '===') and feed it over stdin to a command running in parallel? So the example input above would result in 3 parallel processes (for example a command called do.sh) where each instance received a part of the data on STDIN, like this: do.sh (instance 1) receives this over STDIN: foo bar bar baz do.sh (instance 2) receives this over STDIN: qux bla do.sh (instance 3) receives this over STDIN: def zzz yyy I suppose something like this is possible using xargs or GNU parallel, but I do not know how.

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  • Where has my parallel port gone? ioperm(888,1,1) returns -1.

    - by marcusw
    I have an old Dell Dimension 8200 running Gentoo which I use solely to control various things using the parallel port. After shutting it down a few weeks ago, I started it up again today and tried to access the parallel port like I usually do. Unfortunately, my code bombed out when it tried to call ioperm(888,1,1) to grab the parallel port which returned an error code of -1. There have been no changes to the system be it hardware or software, no updates, no tweaking, no dropping the case, no over-amping the data pins, nothing. The port and the software have been working fine for months with no changes, and were working fine when I shut it down last. Running my code with root privileges changes nothing. What is breaking this and how can I fix it?

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  • Parallel port no longer accessible even though no changes to system.

    - by marcusw
    I have an old Dell Dimension 8200 running Gentoo which I use solely to control various things using the parallel port. After shutting it down a few weeks ago, I started it up again today and tried to access the parallel port like I usually do. Unfortunately, my code bombed out when it tried to call ioperm(888,1,1) to grab the parallel port which returned an error code of -1. There have been no changes to the system be it hardware or software, no updates, no tweaking, no dropping the case, no over-amping the data pins, nothing. The port and the software have been working fine for months with no changes, and were working fine when I shut it down last. Running my code with root privileges changes nothing. What is breaking this and how can I fix it?

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  • C# [Mono]: MPAPI vs MPI.NET vs ?

    - by Olexandr
    Hi. I'm working on college project. I have to develop distributed computing system. And i decided to do some research to make this task fun :) I've found MPAPI and MPI.NET libraries. Yes, they are .NET libraries(Mono, in my case). Why .NET ? I'm choosing between Ada, C++ and C# so to i've choosed C# because of lower development time. I have two goals: Simplicity; Performance; Cluster computing. So, what to choose - MPAPI or MPI.NET or something else ?

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  • MPAPI vs MPI.NET vs ?

    - by Olexandr
    I'm working on college project. I have to develop distributed computing system. And i decided to do some research to make this task fun :) I've found MPAPI and MPI.NET libraries. Yes, they are .NET libraries(Mono, in my case). Why .NET ? I'm choosing between Ada, C++ and C# so to i've choosed C# because of lower development time. I have two goals: Simplicity; Performance; Cluster computing. So, what to choose - MPAPI or MPI.NET or something else ?

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  • Parallelism on two duo-core processor system

    - by Qin
    I wrote a Java program that draw the Mandelbrot image. To make it interesting, I divided the for loop that calculates the color of each pixel into 2 halves; each half will be executed as a thread thus parallelizing the task. On a two core one cpu system, the performance of using two thread approach vs just one main thread is nearly two fold. My question is on a two dual-core processor system, will the parallelized task be split among different processor instead of just utilize the two core on one processor? I suppose the former scenario will be slower than the latter one simply because the latency of communicating between 2 CPU over the motherboard wires. Any ideas? Thanks

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  • Are there references discussing the use parallel programming as a development methodology? [closed]

    - by ahsteele
    I work on a team which employs many of the extreme programming practices. We've gone to great lengths to utilize paired programming as much as possible. Unfortunately the practice sometimes breaks down and becomes ineffective. In looking for ways to tweak our process I came across two articles describing parallel pair programming: Parallel Pair Programming Death of paired programming. Its 2008 move on to parallel pairing While these are good resources I wanted to read a bit more on the topic. As you can imagine Googling for variations on parallel pair programming nets mostly results which relate to parallel programming. What I'm after is additional discussion on the topic of parallel pair programming. Do additional references exist that my Google-fu is unable to discern? Has anyone used the practice and care to share here (thus creating a reference)?

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  • How to you solve the problem of implicit locking and parallel execution?

    - by Eonil
    Where the code is: function A() { lock() doSomething() unlock() } We can call A safely from multiple threads, but it never be executed in parallel . For parallel execution, we have to evade all of this code. But the problem is we never know the A is getting lock or not. If we have source code (maybe lucky case), we have to decode all code to know locking is happening or not. This sucks. But even worse is we normally have no source code. It's obvious this kind of hidden locks will become bottleneck of parallel execution even all the other parts are designed for parallel. And also, (1) With locks, execution cannot be parallel. (2) And I can't know whether the locks are used or not in any code. (3) Defensively, I can't make parallel anything! This facts drives me crazy. How do you solve this problem?

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  • How to break out of a nested parallel (OpenMP) Fortran loop idiomatically?

    - by J.F. Sebastian
    Here's sequential code: do i = 1, n do j = i+1, n if ("some_condition") then result = "here's result" return end if end do end do Is there a cleaner way to execute iterations of the outer loop concurrently other than: !$OMP PARALLEL private(i,j) !$OMP DO do i = 1, n if (found) goto 10 do j = i+1, n if (found) goto 10 if ("some_condition") then !$OMP CRITICAL !$OMP FLUSH if (.not.found) then found = .true. result = "here's result" end if !$OMP FLUSH !$OMP END CRITICAL goto 10 end if end do 10 continue end do !$OMP END DO NOWAIT !$OMP END PARALLEL

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  • What Parallel computing APIs take good use of sockets?

    - by Ole Jak
    What Parallel computing APIs take good use of sockets? So my programm uses soskets, what Parallel computing APIs I can use that would help me but will not obligate me to go from sockets to anything else... I mean when we are on claster with some special, not socket infrastructure sistem that API emulates something like socket but uses that infrustructure (so programm peforms much faster then on sockets, but keeps having nice soskets API)

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