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  • JUnit terminates child threads

    - by Marco
    Hi to all, When i test the execution of a method that creates a child thread, the JUnit test ends before the child thread and kills it. How do i force JUnit to wait for the child thread to complete its execution? Thanks

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  • Using threads and event handlers within a WCF Web Service

    - by user368984
    While making a WCF Web Service, I came across a problem while using a method with a webbrowser control. The method starts a thread and uses a webbrowser control to fill in some forms and click further, waiting for a event handler to fire and return a answer I need. The method is tested and works within its own enviroment, but used in a WCF Web Service enviroment, the event handlers just won't fire. A result of that is the waiting manualresetevent not ending. Is this because of the new thread or because of the bad event handling of the web service? If yes, what is a reasonable solution?

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  • How to know who kills my threads

    - by mcabral
    I got a thread that is just banishing.. i'd like to know who is killing my thread and why. It occurs to me my thread is being killed by the OS, but i'd like to confirm this and if possible to know why it's killing it. As for the thread, i can assert it has at least 40 min of execution before dying, but it suddenly dies around 5 min. public void RunWorker() { Thread worker = new Thread(delegate() { DoSomethingForALongLongTime(); }); worker.IsBackground = true; worker.SetApartmentState(System.Threading.ApartmentState.STA); worker.Start(); }

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  • how to differentiate between two threads

    - by mithun1538
    Hello everyone, I have the following code in my program: Thread getUsersist, getChatUsers; getUsersList = new Thread(this, "getOnlineUsers"); getUsersList.start(); getChatUsers = new Thread(this, "getChatUsers"); getChatUsers.start(); In run(), I wish to know which thread is using run(). If its "getOnlineUsers" i will do something, If it is "getChatUsers" I will do something else. So how do I know which thread is using run()?

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  • Swing and handling threads

    - by James P.
    There's a couple questions here on StackOverflow on the subject of threading with the Swing api but things still aren't clear. What is the issue with the EDT, what is the proper way to initiate a Thread with Swing and in what cases should it be used? P.S: Any sources in terms of good practises would be appreciated.

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  • problem with threads

    - by Nadeem
    i want to be done for 10 times!!, to scan teh number and print it again!!, how i can do that #include <stdio.h> #include <pthread.h> #include <semaphore.h> sem_t m; int n; void *readnumber(void *arg) { scanf("%d",&n); sem_post(&m); } void *writenumber(void *arg) { //int x =3; //while(x>0) //{ //x = x-1; sem_wait(&m); printf("%d",n); //} } int main(){ pthread_t t1, t2; sem_init(&m, 0, 0); pthread_create(&t2, NULL, writenumber, NULL); pthread_create(&t1, NULL, readnumber, NULL); pthread_join(t2, NULL); pthread_join(t1, NULL); sem_destroy(&m); return 0; }

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  • Explain the code: c# locking feature and threads

    - by Mendy
    I used this pattern in a few projects, (this snipped of code is from CodeCampServer), I understand what it does, but I'm really interesting in an explanation about this pattern. Specifically: Why is the double check of _dependenciesRegistered. Why to use lock (Lock){}. Thanks. public class DependencyRegistrarModule : IHttpModule { private static bool _dependenciesRegistered; private static readonly object Lock = new object(); public void Init(HttpApplication context) { context.BeginRequest += context_BeginRequest; } public void Dispose() { } private static void context_BeginRequest(object sender, EventArgs e) { EnsureDependenciesRegistered(); } private static void EnsureDependenciesRegistered() { if (!_dependenciesRegistered) { lock (Lock) { if (!_dependenciesRegistered) { new DependencyRegistrar().ConfigureOnStartup(); _dependenciesRegistered = true; } } } } }

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  • Problem using GDI+ with multiple threads (VB.NET)

    - by Joe B
    I think it would be best if I just copy and pasted the code (it's very trivial). Private Sub Main() Handles MyBase.Shown timer.Interval = 10 timer.Enabled = True End Sub Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint e.Graphics.DrawImage(image, 0, 0) End Sub Private Sub tick() Handles timer.Elapsed Using g = Graphics.FromImage(image) g.Clear(Color.Transparent) g.DrawLine(Pens.Red, 0 + i, 0 + i, Me.Width - i, Me.Height - i) End Using Me.Invalidate() End Sub An exception, "The object is currently in use elsewhere", is raised during the tick event. Could someone tell me why this happens and how to solve it? Thanks.

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  • Passing Data to Multi Threads

    - by alaamh
    I study this code from some book: #include <pthread.h> #include <stdio.h> /* Parameters to print_function. */ struct char_print_parms { /* The character to print. */ char character; /* The number of times to print it. */ int count; }; /* Prints a number of characters to stderr, as given by PARAMETERS, which is a pointer to a struct char_print_parms. */ void* char_print(void* parameters) { /* Cast the cookie pointer to the right type. */ struct char_print_parms* p = (struct char_print_parms*) parameters; int i; for (i = 0; i < p->count; ++i) fputc(p->character, stderr); return NULL; } /* The main program. */ int main() { pthread_t thread1_id; pthread_t thread2_id; struct char_print_parms thread1_args; struct char_print_parms thread2_args; /* Create a new thread to print 30,000 ’x’s. */ thread1_args.character = 'x'; thread1_args.count = 30000; pthread_create(&thread1_id, NULL, &char_print, &thread1_args); /* Create a new thread to print 20,000 o’s. */ thread2_args.character = 'o'; thread2_args.count = 20000; pthread_create(&thread2_id, NULL, &char_print, &thread2_args); usleep(20); return 0; } after running this code, I see different result each time. and some time corrupted result. what is wrong and what the correct way to do that?

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  • In Perl, how can I wait for threads to end in parallel?

    - by Pmarcoen
    I have a Perl script that launches 2 threads,one for each processor. I need it to wait for a thread to end, if one thread ends a new one is spawned. It seems that the join method blocks the rest of the program, therefore the second thread can't end until everything the first thread does is done which sort of defeats its purpose. I tried the is_joinable method but that doesn't seem to do it either. Here is some of my code : use threads; use threads::shared; @file_list = @ARGV; #Our file list $nofiles = $#file_list + 1; #Real number of files $currfile = 1; #Current number of file to process my %MSG : shared; #shared hash $thr0 = threads->new(\&process, shift(@file_list)); $currfile++; $thr1 = threads->new(\&process, shift(@file_list)); $currfile++; while(1){ if ($thr0->is_joinable()) { $thr0->join; #check if there are files left to process if($currfile <= $nofiles){ $thr0 = threads->new(\&process, shift(@file_list)); $currfile++; } } if ($thr1->is_joinable()) { $thr1->join; #check if there are files left to process if($currfile <= $nofiles){ $thr1 = threads->new(\&process, shift(@file_list)); $currfile++; } } } sub process{ print "Opening $currfile of $nofiles\n"; #do some stuff if(some condition){ lock(%MSG); #write stuff to hash } print "Closing $currfile of $nofiles\n"; } The output of this is : Opening 1 of 4 Opening 2 of 4 Closing 1 of 4 Opening 3 of 4 Closing 3 of 4 Opening 4 of 4 Closing 2 of 4 Closing 4 of 4

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  • Skype, green screen, no microphone

    - by EddyThe B
    I have issues with skype using my brand new System 76 Galago Ultrapro, running Ubuntu 13.04. I installed Skype through ubuntu software centre (after allowing Canonical partner stuff), but it won't work, the video is a green screen, and it won't connect to the microphone. The webcam works when using Cheese, and the microphone appears to work in general (it shows sound levels when I go to the Input tab under the Sound settings). I tried to fix the green screen issue using this command: $ echo -e '#!bin/bash n LD_PRELOAD=/usr/lib/i386-linux-gnu/libv4l/v4l1compat.so /usr/bin/skype' | sudo tee /usr/local/bin/skype sudo chmod a+x /usr/local/bin/skype as suggested here: http://debianhelp.wordpress.com/2012/09/28/to-do-list-after-installing-ubuntu-13-04-aka-raring-ringtail-operating-system/ but no luck. Any ideas? I have also asked this question to the System 76 tech support folk.

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  • Connecting Ubuntu 11.10 to Samsung LSCD TV over HDMI TV, gives screen in green and lila

    - by Gorog Imre
    I have a Dell 5720 laptop with ubuntu 11.10. I can't connect to my Samsung LCD TV (over Marantz nr 1601 AV). Audio is ok but the pictures are displayed in two colours: green and lila ! Please send me a massage how can I fix this problem ! Thanks a lot. I am very confused because I do not do anything however it comes(seldom) to the right colouring but only for a while(5minutes) and returns to the green-lila picture again when I do something else for example surfing with firefox or starting other programs ! The settings : resolutions of laptopscreenplay and TV are the same and I did not change the colour profile as well . My laptop screen is HD+ truebright (1600x900) and my TV SAmsung 1280x720 I have no idea what to do my HDMI connection to make right with the colours! How can I fix this situation to gain a stable colouring ?

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  • JAVA: 500 Worker Threads, what kind of thread pool?

    - by Submerged
    I am wondering if this is the best way to do this. I have about 500 threads that run indefinitely, but Thread.sleep for a minute when done one cycle of processing. ExecutorService es = Executors.newFixedThreadPool(list.size()+1); for (int i = 0; i < list.size(); i++) { es.execute(coreAppVector.elementAt(i)); //coreAppVector is a vector of extends thread objects } I do need a separate threads for each running task, so changing the architecture isn't an option. I tried making my threadPool size equal to Runtime.getRuntime().availableProcessors() which attempted to run all 500 threads, but only let 8 (4xhyperthreading) of them execute. The other threads wouldn't surrender and let other threads have their turn. I tried putting in a wait() and notify(), but still no luck. If anyone has a simple example or some tips, I would be grateful!

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  • Is my way of doing threads in Android correct?

    - by Charlie
    Hi, I'm writing a live wallpaper, and I'm forking off two separate threads in my main wallpaper service. One updates, and the other draws. I was under the impression that once you call thread.start(), it took care of everything for you, but after some trial and error, it seems that if I want my update and draw threads to keep running, I have to manually keep calling their run() methods? In other words, instead of calling start() on both threads and forgetting, I have to manually set up a delayed handler event that calls thread.run() on both the update and draw threads every 16 milliseconds. Is this the correct way of having a long running thread? Also, to kill threads, I'm just setting them to be daemons, then nulling them out. Is this method ok? Most examples I see use some sort of join() / interrupt() in a while loop...I don't understand that one...

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  • Performance degrades for more than 2 threads on Xeon X5355

    - by zoolii
    Hi All, I am writing an application using boost threads and using boost barriers to synchronize the threads. I have two machines to test the application. Machine 1 is a core2 duo (T8300) cpu machine (windows XP professional - 4GB RAM) where I am getting following performance figures : Number of threads :1 , TPS :21 Number of threads :2 , TPS :35 (66 % improvement) further increase in number of threads decreases the TPS but that is understandable as the machine has only two cores. Machine 2 is a 2 quad core ( Xeon X5355) cpu machine (windows 2003 server with 4GB RAM) and has 8 effective cores. Number of threads :1 , TPS :21 Number of threads :2 , TPS :27 (28 % improvement) Number of threads :4 , TPS :25 Number of threads :8 , TPS :24 As you can see, performance is degrading after 2 threads (though it has 8 cores). If the program has some bottle neck , then for 2 thread also it should have degraded. Any idea? , Explanations ? , Does the OS has some role in performance ? - It seems like the Core2duo (2.4GHz) scales better than Xeon X5355 (2.66GHz) though it has better clock speed. Thank you -Zoolii

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  • ODEE Green Field (Windows) Part 5 - Deployment and Validation

    - by AndyL-Oracle
    And here we are, almost finished with our installation of Oracle Documaker Enterprise Edition ("ODEE") in a Windows green field environment. Let's recap what we've done so far: In part 1, I went over the basic process that I intended to show with installing an ODEE on a green field server. I walked you through the basic installation of Oracle 11g database In part 2, I covered the installation of WebLogic application server. In part 3, I showed you how to install SOA Suite for WebLogic. In part 4, we did the first part of the installation of ODEE itself. What remains after all of that, is the deployment of the ODEE components onto the database and application server - so let's get to it! DATABASE First, we'll deploy the schemas to the database. The schemas are created during the ODEE installation according to the responses provided during the install process. To deploy the schemas, you'll need to login to the database server in your green field environment. Open a command line and CD into ODEE_HOME\documaker\database\oracle11g.Run SQLPLUS as SYSDBA and execute dmkr_admin.sql:  sqlplus / as sysdba @dmkr_admin.sql Execute dmkr_asline.sql, dmkr_admin_correspondence_example.sql.  If you require additional languages, run the appropriate SQL scripts (e.g. dmkr_asline_es.sql for Spanish). APPLICATION SERVER Next, we'll deploy the WebLogic domain and it's components - Documaker web services, Documaker Interactive, Documaker dashboard, and more. To deploy the components, you'll need to login to the application server in your green field environment. 1. Open Windows Explorer and navigate to ODEE_HOME\documaker\j2ee\weblogic\oracle11g\scripts.2. Using a text editor such as Notepad++, modify weblogic_installation_properties and set location of MIDDLEWARE_HOME and ODEE HOME. If you have used the defaults you’ll probably need to change the E: to C: and that’s it. Save the changes.3. Continuing in the same directory, use your text editor to modify set_middleware_env.cmd and set the drive and path to MIDDLEWARE_HOME. If you have used the defaults you’ll probably need to just change E: to C: and that’s it. Save the changes.4. In the same directory, execute wls_create_domain.cmd by double-clicking it. This should run to completion. If it does not, review any errors and correct them, and rerun the script.5. In the same directory, execute wls_add_correspondence.cmd by double-clicking it - again this should run to completion. 6. Next, we'll start the AdminServer - this is the main WebLogic domain server. To start it, use Windows Explorer and navigate to MIDDLEWARE_HOME\user_projects\domains\idocumaker_domain. Double-click startWebLogic.cmd and the server startup will begin. Once you see output that indicates that the server status changed to RUNNING you may proceed.  a. Note: if you saw database connection errors, you probably didn’t make sure your database name and connection type match. You can change this manually in the WebLogic Console. Open a browser and navigate to http://localhost:7001/console (replace localhost with the name of your application server host if you aren't opening the browser on the server), and login with the the weblogic credential you provided in the ODEE installation process. b. Once you're logged in, open Services?Data Sources. Select dmkr_admin and click Connection Pool.  c. The end of the URL should match the connection type you chose. If you chose ServiceName, the URL should be: jdbc:oracle:thin:@//<hostname>:1521/<serviceName> and if you chose SID, the URL should be: jdbc:oracle:thin:@//<hostname>:1521/<SIDname> d. An example serviceName is a fully qualified DNS-style name, e.g. "idmaker.us.oracle.com". (It does not need to actually resolve in DNS). An example SID is just a name, e.g. IDMAKER. e. Save the change and repeat for the data source dmkr_asline.  f. You will also need to make the same changes in the ODEE_HOME/documaker/docfactory/config/context/.bindings file - open the file in a text editor, locate the URL lines and make the appropriate change, then save the file.  7. Back in the ODEE_HOME\documaker\j2ee\weblogic\oracle11g\scripts directory, execute create_users_groups.cmd. 8. In the same directory, execute create_users_groups_correspondence_example.cmd. 9. Open a browser and navigate to http://localhost:7001/jpsquery. Replace localhost with the name of your application server host if you aren't running the browser on the application server. If you changed the default port for the AdminServer from 7001, use the port you changed it to. You should see output like this: 10. Start the WebLogic managed servers by opening a command prompt and navigating to MIDDLEWARE_HOME/user_projects/domains/idocumaker_domain/bin/. When you start the servers listed below, you will be prompted to enter the WebLogic credentials to start the server. You can prevent this by providing the credential in the startManagedwebLogic.cmd file for the WLS_USER and WLS_PASS values. Note that the credential will be stored in cleartext. To start the server, type in the command shown. a. Start the JMS Server: ./startManagedWebLogic.cmd jms_server b. Start Dashboard/Documaker Administrator: ./startManagedWebLogic.cmd dmkr_server c. Start Documaker Interactive for Correspondence: ./startManagedWebLogic.cmd idm_server SOA Composites  If you're planning on testing out the approval process components of BPEL that can be used with Documaker Interactive, then use the following steps to deploy the SOA composites. If you're not going to use BPEL, you can skip to the next section.1. Stop the servers listed in the previous section (Step 10) in the reverse order that they were started.2. Run the Domain configuration command: navigate to and execute MIDDLEWARE_HOME/wlserver_10.3/common/bin/config.cmd.3. Select Extend and click next. 4. Select the iDocumaker Domain and click Next. 5. Select the Oracle SOA Suite – 11.1.1.0 (this may automatically select other components which is OK). Click Next. 6. View the Configure JDBC resources screen. You should not make any changes. Click Next. 7. Check both connections and click Test Connections. After successful test, click Next. If the tests fail, something is broken. Go back to configure JDBC resources and check your service name/SID. 8. Check all schemas. Set a password (will be the same for all schemas). Enter the database information (service name, host name, port). Click Next. 9. Connections should test successfully. If not, go back and fix any errors. Click Next. 10. Click Next to pass through Optional Configuration. 11. Click Extend. 12. Click Done. 13. Open a terminal window and navigate to/execute: ODEE_HOME/documaker/j2ee/weblogic/oracle11g/bpel/antbuild.cmd14. Start the WebLogic Servers – AdminServer, jms_server, dmkr_server, idm_server. If you forgot how to do this, see the previous section Step 10. Note: if you previously changed the startManagedWebLogic.cmd script for WLS_USER and WLS_PASS you will need to make those changes again. 15. Start the WebLogic server soa_server1: MIDDLEWARE_HOME/user_projects/domains/idocumaker_domain/bin/startManagedWebLogic.cmd soa_server116. Open a browser to http://localhost:7001/console and login. 17. Navigate to Services?Data Sources and select DMKR_ASLINE. 18. Click the Targets tab. Check soa_server1, then click Save. Repeat for the DMKR_ADMIN data source. 19. Open a command prompt and navigate to ODEE_HOME/j2ee/weblogic/oracle11g/scripts, then execute deploy_soa.cmd. That's it! (As if that wasn't enough?) DOCUMAKER Deploy the sample MRL resources by navigating to/executing ODEE_HOME/documaker/mstrres/dmres/deploysamplemrl.bat. You should see approximately 500 resources deployed into the database. Start the Factory Services. Start?Run?services.msc. Locate the service named "ODDF xxxx" and right-click, select Start. Note that each Assembly Line has a separate Factory setup, including its own Factory service and Docupresentment service. The services are named for the assembly line and the machine on which they are installed (because you could have multiple machines servicing a single assembly line, so this allows for easy scripting to control all the services if you choose to do so. Repeat for the Docupresentment service. Note that each Assembly Line has a separate Docupresentment. Using Windows Explorer, navigate to ODEE_HOME/documaker/mstrres/dmres/input and select one of the XML files, and copy it into ODEE_HOME/documaker/hotdirectory. Note: if you chose a different hot directory during installation, copy the file there instead. Momentarily you should see the XML file disappear! Open browser and navigate to http://localhost:10001/DocumakerDashboard (previous versions 12.0-12.2 use http://localhost:10001/dashboard) and verify that job processed successfully. Note that some transactions may fail if you do not have a properly configured email server, and this is ok. You can set up a simple SMTP server (just search the internet for "SMTP developer" and you'll get several to choose from.  So... that's it? Where are we at this point? You now have a completely functional ODEE installation, from soup to nuts as they say. You can further expand your installation by doing some of the following activities: clustering WebLogic services configuring WebLogic for redundancy configuring Oracle 11g for RAC adding additional Factory servers for redundancy/processing capacity setting up a real MRL (instead of the sample resources) testing Documaker Web Services for job submission and more!  I certainly hope you've enjoyed this and find it useful. If you find yourself running into trouble, visit the Oracle Community for Documaker - there is plenty of activity there and you can ask questions. For more concentrated assistance, you can engage an Oracle consultant who is a subject matter expert to assist you. Feel free to email me [andy (dot) little (at) oracle (dot) com] and I can connect you with the appropriate resource to get started. Best of luck! -Andy 

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  • Turn a Green Laser into a Microscope Projector [Science]

    - by ETC
    No need to settle for squinting over a microscope, hack a green laser and a cheap webcam lens into a projector. Check out the video below to see the projector in action. Over at Hackteria, user Dusjagr shares a clever tutorial on how to hack a laser and some odd parts into a projector intended for microscopic subjects. With a strong enough light source, a properly spaced lens assembly, and a slide or petri dish filled with something of interest, you can create microscope projector. Curious how it would work and what the results would look like? Check out this demonstration video: That wiggling creature you see in the video is a nematode from a sample of pond water. For more information on building your own laser-scope projector, hit up the link below. DIY Laser Microscope [Hackteria via Make] Latest Features How-To Geek ETC Learn To Adjust Contrast Like a Pro in Photoshop, GIMP, and Paint.NET Have You Ever Wondered How Your Operating System Got Its Name? Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions Awesome 10 Meter Curved Touchscreen at the University of Groningen [Video] TV Antenna Helper Makes HDTV Antenna Calibration a Snap Turn a Green Laser into a Microscope Projector [Science] The Open Road Awaits [Wallpaper] N64oid Brings N64 Emulation to Android Devices Super-Charge GIMP’s Image Editing Capabilities with G’MIC [Cross-Platform]

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  • Meet "Faces of Fusion": Aaron Green

    - by Natalia Rachelson
    If you are like us, you might be interested in knowing what Fusion Apps Development folks are currently working on.  Wouldn't be cool to get into that Fusion 'kitchen" and see what is cooking and what flavors are getting mixed in together?  Well, this is that special opportunity.  Join us as we meet the creators of Fusion Applications through our "Faces of Fusion" video series.  Watch as these fun loving, interesting people talk about their passions and how these passions drove them to create Fusion.  They explain what makes Fusion special and why they are excited to be working on it. And one by one, they share the satisfaction of hearing customers say WOW! Our featured Oracle Fusion HCM guru this week is Aaron Green. We think his enthusiasm for Fusion is contagious, but you be the judge.  Please sit back and enjoy Aaron Green on Oracle Fusion Applications YouTube Channel 

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  • Graduated transition from Green - Yellow - Red

    - by GoldBishop
    I have am having algorithm mental block in designing a way to transition from Green to Red, as smoothly as possible with a, potentially, unknown length of time to transition. For testing purposes, i will be using 300 as my model timespan but the methodology algorithm design needs to be flexible enough to account for larger or even smaller timespans. Figured using RGB would probably be the best to transition with, but open to other color creation types, assuming its native to .Net (VB/C#). Currently i have: t = 300 x = t/2 z = 0 low = Green (0, 255, 0) mid = Yellow (255, 255, 0) high = Red (255, 0, 0) Lastly, sort of an optional piece, is to account for the possibility of the low, mid, and high color's to be flexible as well. I assume that there would need to be a check to make sure that someone isnt putting in low = (255,0,0), mid=(254,0,0), and high=(253,0,0). Outside of this anomaly, which i will handle myself based on the best approach to evaluate a color. Question: What would be the best approach to do the transition from low to mid and then from mid to high? What would be some potential pitfalls of implementing this type of design, if any?

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  • Linux per-process resource limits - a deep Red Hat Mystery

    - by BobBanana
    I have my own multithreaded C program which scales in speed smoothly with the number of CPU cores.. I can run it with 1, 2, 3, etc threads and get linear speedup.. up to about 5.5x speed on a 6-core CPU on a Ubuntu Linux box. I had an opportunity to run the program on a very high end Sunfire x4450 with 4 quad-core Xeon processors, running Red Hat Enterprise Linux. I was eagerly anticipating seeing how fast the 16 cores could run my program with 16 threads.. But it runs at the same speed as just TWO threads! Much hair-pulling and debugging later, I see that my program really is creating all the threads, they really are running simultaneously, but the threads themselves are slower than they should be. 2 threads runs about 1.7x faster than 1, but 3, 4, 8, 10, 16 threads all run at just net 1.9x! I can see all the threads are running (not stalled or sleeping), they're just slow. To check that the HARDWARE wasn't at fault, I ran SIXTEEN copies of my program independently, simultaneously. They all ran at full speed. There really are 16 cores and they really do run at full speed and there really is enough RAM (in fact this machine has 64GB, and I only use 1GB per process). So, my question is if there's some OPERATING SYSTEM explanation, perhaps some per-process resource limit which automatically scales back thread scheduling to keep one process from hogging the machine. Clues are: My program does not access the disk or network. It's CPU limited. Its speed scales linearly on a single CPU box in Ubuntu Linux with a hexacore i7 for 1-6 threads. 6 threads is effectively 6x speedup. My program never runs faster than 2x speedup on this 16 core Sunfire Xeon box, for any number of threads from 2-16. Running 16 copies of my program single threaded runs perfectly, all 16 running at once at full speed. top shows 1600% of CPUs allocated. /proc/cpuinfo shows all 16 cores running at full 2.9GHz speed (not low frequency idle speed of 1.6GHz) There's 48GB of RAM free, it is not swapping. What's happening? Is there some process CPU limit policy? How could I measure it if so? What else could explain this behavior? Thanks for your ideas to solve this, the Great Xeon Slowdown Mystery of 2010!

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  • Threads slowing down application and not working properly

    - by Belgin
    I'm making a software renderer which does per-polygon rasterization using a floating point digital differential analyzer algorithm. My idea was to create two threads for rasterization and have them work like so: one thread draws each even scanline in a polygon and the other thread draws each odd scanline, and they both start working at the same time, but the main application waits for both of them to finish and then pauses them before continuing with other computations. As this is the first time I'm making a threaded application, I'm not sure if the following method for thread synchronization is correct: First of all, I use two global variables to control the two threads, if a global variable is set to 1, that means the thread can start working, otherwise it must not work. This is checked by the thread running an infinite loop and if it detects that the global variable has changed its value, it does its job and then sets the variable back to 0 again. The main program also uses an empty while to check when both variables become 0 after setting them to 1. Second, each thread is assigned a global structure which contains information about the triangle that is about to be rasterized. The structures are filled in by the main program before setting the global variables to 1. My dilemma is that, while this process works under some conditions, it slows down the program considerably, and also it fails to run properly when compiled for Release in Visual Studio, or when compiled with any sort of -O optimization with gcc (i.e. nothing on screen, even SEGFAULTs). The program isn't much faster by default without threads, which you can see for yourself by commenting out the #define THREADS directive, but if I apply optimizations, it becomes much faster (especially with gcc -Ofast -march=native). N.B. It might not compile with gcc because of fscanf_s calls, but you can replace those with the usual fscanf, if you wish to use gcc. Because there is a lot of code, too much for here or pastebin, I created a git repository where you can view it. My questions are: Why does adding these two threads slow down my application? Why doesn't it work when compiling for Release or with optimizations? Can I speed up the application with threads? If so, how? Thanks in advance.

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