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  • executorservice to read data from database in chuncks and run process on them

    - by TazMan
    I'm trying to write a process that would read data from a database and upload it onto a cloud datastore. How can I decide the partition strategy of the data? I want to query the table in chunks and process each chunk in 10 threads. Each thread basically will send the data to an individual node on a 10 node cluster on the cloud.. Where in the below multi threading code will the dataquery to extract and send 10 concurrent requests for uploading data to cloud would be? public class Caller { public static void main(String[] args) { ExecutorService executor = Executors.newFixedThreadPool(10); for (int i = 0; i < 10; i++) { Runnable worker = new DomainCDCProcessor(i); executor.execute(worker); } executor.shutdown(); while (!executor.isTerminated()) { } System.out.println("Finished all threads"); } }

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  • Possible to implement an IsViewPortVisible dependencyproperty for an item in an ItemsControl?

    - by Matt H.
    I need to enable/disable spell checking in a richtextbox in an ItemsControl, based on whether the RichTextBox is visible in the ItemsControl's Scrollviewer. I think the route is to implement an IsViewPortVisible dependency property and wire an event handler for a changed event... I found this article that describes the lengthy process for determining if an item is in the viewport: http://social.msdn.microsoft.com/Forums/en/wpf/thread/e6ccfec3-3dc0-4702-9d0d-1cfa55ecfc90 Any ideas on where to start? I'm familiar with implementing my own dependency property for the sake of simple bindings (integers, strings, etc...). I have no idea how to undergo something like this though) This is the end result I'm hoping for: <DataTemplate> <Grid> ...Stuff in the Grid <local:CustomRichTextBox SpellCheck.IsEnabled={Binding RelativeSource={RelativeSource Self}, Path=IsViewPortVisible}/> </Grid> </DataTemplate> Help will be EXTREMELY appreciated... you'll be saving me about 500MB in memory consumption while the program is running!!!! :)

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  • remine focus on the main activity (while switching activities)

    - by rayman
    Hi, Ive got two activities in the same application. the first one is with gui(main activity) the second one is a listener which works infinite without gui. Wierd problem occurs: i am running the second activity with a diffrent thread so i could keep on manipulate the gui.. but for some reason, the gui losing it's focus for some reason, only when i press 'home' and come back to it, then i can continune maniuplate the gui. it feels like after i launch the second activity, the gui activity(the main) is losing the focus. how come? in my mainactivity i have: setContentView(R.layout.main); and its setted as the launcher in the manifest. thanks, ray.

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  • Jmeter Query new user

    - by Sri
    First of all apologies for the below question. Am from a Testing background for the past 8 years and very novice to Jmeter. I went through the Jmeter site, and ran a sample recording using the jmeter.apache.org site and it went fine. I want to test my knowledge and understanding. So, I did the following way. Created a thread group. Added a config element HTTP Default Requests with server name as mail.google.com. Added a Sampler as HTTP request, set the METHOD to POST and gave the username and password, and i ran the test. When i see the Results Viewer, i could see the login page of gmail, I need to know how to pass my username and password and simulate the clicking of Submit button and getting the next page. Please help, am very new and will really appreciate if it's explained as simple as possible.

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  • Threaded application sleeps with other application

    - by DeeD
    I have a weird problem with my threaded software. I start 2 instances of the software. Each instance has 2 threads, one thread creates a socket to use, and the other one is uses the socket for communication. When one of the threads in one instance calls sleep(3), the other threads in the the other instance sleeps too. And the weirdest thing is that when I rebooted the computer, it works the first time, but after trying a second time, it sleeps like described. How is this possible? Is it using some shared resource?

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  • Queued WCF Service which processes every X seconds

    - by Jeff Windsor
    I need to create a service which can process queued requests on a configured time interval. For example go to the web and get financial data from a site the requires we limit requests to once per second. I am new to WCF and I am not sure if (1) WCF with MSMQ a proper choice for implementing this? and (2) if so what is the best mechanism for enforcing the interval? a thread wait? a timer (not sure how that would work).

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  • How do I determine darker or lighter color variant of a given color?

    - by Nidonocu
    Given a source color of any hue by the system or user, I'd like a simple algorithm I can use to work out a lighter or darker variants of the selected color. Similar to effects used on Windows Live Messenger for styling the user interface. Language is C# with .net 3.5. Responding to comment: Color format is (Alpha)RGB. With values as bytes or floats. Marking answer: For the context of my use (a few simple UI effects), the answer I'm marking as accepted is actually the most simple for this context. However, I've given up votes to the more complex and accurate answers too. Anyone doing more advanced color operations and finding this thread in future should definitely check those out. Thanks SO. :)

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  • What is the absolute fastest way to implement a concurrent queue with ONLY one consumer and one producer?

    - by JohnPristine
    java.util.concurrent.ConcurrentLinkedQueue comes to mind, but is it really optimum for this two-thread scenario? I am looking for the minimum latency possible on both sides (producer and consumer). If the queue is empty you can immediately return null AND if the queue is full you can immediately discard the entry you are offering. Does ConcurrentLinkedQueue use super fast and light locks (AtomicBoolean) ? Has anyone benchmarked ConcurrentLinkedQueue or knows about the ultimate fastest way of doing that? Additional Details: I imagine the queue should be a fair one, meaning the consumer should not make the consumer wait any longer than it needs (by front-running it) and vice-versa.

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  • Commands implicitly threaded in Makefiles ?

    - by apple92
    Hi, I have a "super" makefile which launches two "sub" make file: libwebcam: @echo -e "\nInvoking libwebcam make." $(MAKE) -C $(TOPDIR)/libwebcam uvcdynctrl: @echo -e "\nInvoking uvcdynctrl make." $(MAKE) -C $(TOPDIR)/uvcdynctrl uvcdynctrl uses libwebcam... I noticed that those two builds are launched as separate threads by make ! Thus sometimes the lib is not available when uvcdynctrl starts being built, and I get errors. By default, make should not launch commands as threads since this is available only through -j (number of jobs) and, according to the make manual, there is no thread by default. I run this on an Ubuntu. Did someone face the same issue ? Apple92

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  • Project works in eclipse but not when exported

    - by Mike
    I wrote an application that uses GraphViz to generate some graphs as .gif's according to the DOT syntax. When I run from Eclipse the images are generated fine but when I export it as a jar the images are created but there is no data in them. When I view them in Microsoft Picture Viewer its just the red X. It was working as an exported jar until I put the picture generation in its own thread. I can't seem to figure out whats going on here. Are there any problems exporting multi-threaded projects? Any one have any ideas? Thanks

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  • How to run "android.bat sdk" in Window 7

    - by user1730495
    I have downloaded and installed Android SDK and tried to start android.bat sdk but got following exception: C:\products\Android\tools>android.bat sdk Exception in thread "main" java.lang.UnsatisfiedLinkError: no swt-win32-3550 or swt-win32 in swt.library.path, java.library.path or the jar file at org.eclipse.swt.internal.Library.loadLibrary(Unknown Source) at org.eclipse.swt.internal.Library.loadLibrary(Unknown Source) at org.eclipse.swt.internal.C.<clinit>(Unknown Source) at org.eclipse.swt.widgets.Display.<clinit>(Unknown Source) at com.android.sdkmanager.Main.showSdkManagerWindow(Main.java:328) at com.android.sdkmanager.Main.doAction(Main.java:302) at com.android.sdkmanager.Main.run(Main.java:118) at com.android.sdkmanager.Main.main(Main.java:101) I have searched for solution a long time but I cannot get it to work. Is there anything I have to set up first?

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  • Lua operations, that works in mutitheaded environment

    - by SBKarr
    My application uses Lua in multithreaded environment with global mutex. It implemented like this: Thread locks mutex, Call lua_newthread Perform some initialization on coroutine Run lua_resume on coroutine Unlocks mutex lua_lock/unlock is not implemented, GC is stopped, when lua works with coroutine. My question is, can I perform steps 2 and 3 without locking, if initialisation process does not requires any global Lua structs? Can i perform all this process without locking at all, if coroutine does not requires globals too? In what case I generally can use Lua functions without locking?

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  • Embedded Java Databases for Large Data Sets

    - by ExAmerican
    I would like to port a PHP/MySQL-based client/server application to be a standalone desktop application written in Java. The database has grown to be fairly large, with several tables with hundreds of thousands of rows. I expect these could grow to over a million entries for certain tables. What embedded database would best handle this? HSQLDB and Sqlite seem to be the obvious choices, though I'm guessing there are others out there as well. My main priorities are the ability to perform queries on large amounts of data efficiently (this thread seems to confirm Sqlite can handle this) and the ease with which I can import old data from MySQL (I remember HSQLDB being kind of a pain for that). Note: I am aware that similar questions comparing embedded databases have been posted before (for example here and here) but as my priorities differ somewhat from most applications considering the large data migration I thought it justified a new question.

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  • How do I guarantee row uniqueness in MySQL without the use of a UNIQUE constraint?

    - by MalcomTucker
    Hi I have some fairly simple requirements but I'm not sure how I implement them: I have multiple concurrent threads running the same query The query supplies a 'string' value - if it exists in the table, the query should return the id of the matching row, if not the query should insert the 'string' value and return the last inserted id The 'string' column is (and must be) a text column (it's bigger than varchar 255) so I cannot set it as unique - uniqueness must be enforced through the access mechanism The query needs to be in stored procedure format (which doesnt support table locks in MySQL) How can I guarantee that 'string' is unique? How can I prevent other threads writing to the table after another thread has read it and found no matching 'string' item? Thanks for any advice..

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  • Creating a System.Windows.Controls.Image throws an exception - how do I use the dispatcher to instan

    - by Scott Whitlock
    I'm running my unit tests on a piece of code that does the following in the test: Assert.IsNotNull(target.Icon); Inside the getter for the Icon property, I'm doing this: System.Windows.Controls.Image img = new System.Windows.Controls.Image(); That's throwing this exception: System.InvalidOperationException : The calling thread must be STA, because many UI components require this. I understand what that means, and I understand that I need to use the Dispatcher, but I'm a bit confused about how or why... this is a property of my ViewModel and I don't get any of these exceptions when running the application. Other info: this only started failing when I upgraded to .NET 4.

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  • UITableViewController executes delate functions before network request finishes

    - by user1543132
    I'm having trouble trying to populate a UITableView with the results of a network request. It seems that my code is alright as it works perfectly when my network is speedy, however, when it's not, the function - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath- still executes, which results in a bad access error. I presume that this is because the array that the aforesaid function attempts to utilize has not been populated. This brings me to my question: Is there anyway that I can have the UITableView delegate methods delayed to avoid this? - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"AlbumsCell"; //UITableViewCell *basicCell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath]; AlbumsCell *cell = (AlbumsCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (!cell) { **// Here is where the Thread 1: EXC_BAD_ACCESS (code=2 address=0x8)** cell = [[[AlbumsCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } Album *album = [_albums objectAtIndex:[indexPath row]]; [cell setAlbum:album]; return cell; }

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  • asp.net impersonation identity: Where does it come from?

    - by Rising Star
    Here's a simple question I've been stuck on for a while. When I set < identity impersonate=true > in my web.config so that asp.net impersonates the logged on user automatically (or the anonymous account if not using Windows Authentication), where does the identity that asp.net impersonates come from? This document: http://msdn.microsoft.com/en-us/library/ff649264.aspx shows three places you can retrieve information about the logged on user: Httpcontext.Current.user System.Threading.Thread.Current System.Security.Principal.WindowsIdentity.GetCurrent It seems that none of these locations consistently match the identity that gets impersonated when I set < identity impersonate=true > in web.config. I would like to know where the impersonated identity comes from.

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  • Wait for animation, render to complete - XAML and C#

    - by Adam S
    Hi all. I have a situation where I am animating part of my XAML application, and I need to wait for the animation AND rendering to complete before I can move on in my code. So far the tail end of my function looks like: ProcExpandCollapse.Begin(); while (ProcExpandCollapse.GetCurrentState() != ClockState.Stopped) { } } Which, in theory, will wait until the animation is finished. But it will not wait until the rendering is finished - the thread drawing the application might still not have re-drawn the animation. The animation is expanding a UIElement, and then the next part of my code uses it's rendered size to do some things. My question then is, how do I wait until my UI Element is re-rendered before moving on?

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  • [grails + xfire] How to handle errors in SOAP services?

    - by Mulone
    Hi all, I'm implementing a web service on the xfire plugin. I was wondering how I'm supposed to handle the errors. I tried with this setup but the error is not returned to the SOAP client: GaSession[] myMethod( String userId ) throws MyException{ GaUser user = GaUser.findByUserId( userId ) if (!user) throw new MyException("user ${userId} does not exist") // do stuff and return valid results } Is there a standard way to handle errors and return them to the client in a clear way? My log is full of messages like: 2010-06-13 18:20:40,926 [Thread-289] DEBUG aegis.XMLClassMetaInfoManager - Mapping file : /com/mycompany/MyClass.aegis.xml not found. Is there a way to fix this? Cheers!

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  • Take advantage of multiple cores executing SQL statements

    - by willvv
    I have a small application that reads XML files and inserts the information on a SQL DB. There are ~ 300 000 files to import, each one with ~ 1000 records. I started the application on 20% of the files and it has been running for 18 hours now, I hope I can improve this time for the rest of the files. I'm not using a multi-thread approach, but since the computer I'm running the process on has 4 cores I was thinking on doing it to get some improvement on the performance (although I guess the main problem is the I/O and not only the processing). I was thinking on using the BeginExecutingNonQuery() method on the SqlCommand object I create for each insertion, but I don't know if I should limit the max amount of simultaneous threads (nor I know how to do it). What's your advice to get the best CPU utilization? Thanks

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  • embedded dev. question - how to break free from a faulty serial port opening?

    - by user347266
    Under WindowsCE, C++ project, I'm trying to work with devices connected via both "real" serial ports and/or serial-to-usb wrappers ("virtual" serial ports); my problem is - when I try to open the port, if something goes wrong, the function never returns and the system goes into some non-responsive state and has to be eventually rebooted. I need to open the ports from the main thread. The question is - how can I make it happen in a controlled way?? this is the opening code snippet: std::ostringstream device_name; device_name << "\\.\COM" << port; m_port = ::CreateFile(device_name.str().c_str(), GENERIC_READ | GENERIC_WRITE, 0, // exclusive access NULL, // no security OPEN_EXISTING, FILE_FLAG_OVERLAPPED, // overlapped I/O NULL); // null template any suggestions would be greatly appreciated thanks!

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  • How does lock(syncRoot) make sense on a static method?

    - by Rising Star
    The following code is excerpted from the (Windows Identity Foundation SDK) template that MS uses to create a new Security Token Service Web Site. public static CustomSecurityTokenServiceConfiguration Current { get { HttpApplicationState httpAppState = HttpContext.Current.Application; CustomSecurityTokenServiceConfiguration customConfiguration = httpAppState.Get( CustomSecurityTokenServiceConfigurationKey ) as CustomSecurityTokenServiceConfiguration; if ( customConfiguration == null ) { lock ( syncRoot ) { customConfiguration = httpAppState.Get( CustomSecurityTokenServiceConfigurationKey ) as CustomSecurityTokenServiceConfiguration; if ( customConfiguration == null ) { customConfiguration = new CustomSecurityTokenServiceConfiguration(); httpAppState.Add( CustomSecurityTokenServiceConfigurationKey, customConfiguration ); } } } return customConfiguration; } } I'm relatively new to multi-threaded programming. I assume that the reason for the lock statement is to make this code thread-safe in the event that two web requests arrive at the web site at the same time. However, I would have thought that using lock (syncRoot) would not make sense because syncRoot refers to the current instance that this method is operating on... but this is a static method? How does this make sense?

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  • java version 1.6 applet requistes

    - by gautam
    Hi, I upgraded my java version 1.5 to 1.6. My applet is not working what are prequesties ? i have changed classid and MIME type to 1.6. Its giving exception: load: class com.timer.AppletGenerator.class not found. java.lang.ClassNotFoundException: com.timer.AppletGenerator.class at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source) at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source) at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: java.io.IOException: open HTTP connection failed:http://localhost:8080/Perfmonitoringgui-000.004.000/com/timer/AppletGenerator/class.class at sun.plugin2.applet.Applet2ClassLoader.getBytes(Unknown Source) at sun.plugin2.applet.Applet2ClassLoader.access$000(Unknown Source) at sun.plugin2.applet.Applet2ClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) ... 7 more Exception: java.lang.ClassNotFoundException: com.timer.AppletGenerator.class Thanks

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  • Re-ordering C++ template functions

    - by DeadMG
    In C++, I have a certain template function that, on a given condition, calls a template function in another class. The trouble is that the other class requires the full definition of the first class to be implemented, as it creates the second class and stores them and manages them in similar fashions. The trouble is that naturally, they fall as one class, and thus have some tight interop, except that I need them to be two classes for threading reasons. A sort of, master for all threads, one child per thread, system. Any advice on how this can be implemented?

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  • SQL Server concurrency and generated sequence

    - by Goyuix
    I need a sequence of numbers for an application, and I am hoping to leverage the abilities of SQL Server to do it. I have created the following table and procedure (in SQL Server 2005): CREATE TABLE sequences ( seq_name varchar(50) NOT NULL, seq_value int NOT NULL ) CREATE PROCEDURE nextval @seq_name varchar(50) AS BEGIN DECLARE @seq_value INT SET @seq_value = -1 UPDATE sequences SET @seq_value = seq_value = seq_value + 1 WHERE seq_name = @seq_name RETURN @seq_value END I am a little concerned that without locking the table/row another request could happen concurrently and end up returning the same number to another thread or client. This would be very bad obviously. Is this design safe in this regard? Is there something I can add that would add the necessary locking to make it safe? Note: I am aware of IDENTITY inserts in SQL Server - and that is not what I am looking for this in particular case. Specifically, I don't want to be inserting/deleting rows. This is basically to have a central table that manages the sequential number generator for a bunch of sequences.

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