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  • How to set UCS2 in numpy?

    - by mindcorrosive
    I'm trying to build numpy 1.2.1 as a module for a third-party python interpreter (custom-built, py2.4 linux x86_64) so that I can make calls to numpy from within it. Let's call this one interpreter A. The thing is, the system-wide python interpreter (also py2.4, let's call it B) from the vendor is built with --enable-unicode=ucs4, while the custom one is with UCS2. Needless to say, when I try to build a module with B, I get an error when I try to import numpy in A -- it complains about undefined symbol _PyUnicodeUCS4_IsWhiteSpace. I've searched around and apparently there's no way around this but to compile a custom Python interpreter -- which I did (let's call it interpreter C), properly specifying the unicode string length (verifiable through sys.maxunicode). I managed to build numpy with C as well, surprisingly enough, but still the problem persists when I try to import it in interpreter C. Previously, when I built numpy using B, there were no problems when importing it in B, but A would complain. Perhaps there's an option when building numpy to specify the length of Unicode strings to be used, as when configuring Python builds? Or am I doing something else wrong? A few notes: Upgrading to newer versions of python and/or numpy is not an option - interpreter A will stay on this version of the grammar for the foreseeable future. Also, it is not possible to start the interpreter A in standalone mode to build numpy with it, as it needs some other libraries preloaded I know that this whole thing is a mess, but I'd appreciate any help I can get to make this work. If you need more information, please let me know, I'd be happy to oblige. Thanks to everybody for their time in advance.

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  • Insert Comment Reply Form Into Page Using Jquery

    - by Joe
    I have been making a threaded comment system as a way to learn php and javascript/jquery properly. Ive done bits and bobs in the past but ive made a new years resolution to learn it properly. Im having trouble inserting a reply form into the comment tree below the comment being replied to. I know this is probably pretty basic but how do you insert html into a page when someone clicks a link. This code wasn't working for me: $(document).ready(function(){ $(function() { $('a#reply').click(function() { $(this).append("the html blah"); }); }); }); Anyone see where im going wrong?

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  • how to kill (or avoid) zombie processes with subprocess module

    - by Dave
    When I kick off a python script from within another python script using the subprocess module, a zombie process is created when the subprocess "completes". I am unable to kill this subprocess unless I kill my parent python process. Is there a way to kill the subprocess without killing the parent? I know I can do this by using wait(), but I need to run my script with no_wait().

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  • Cache consistency & spawning a thread

    - by Dave Keck
    Background I've been reading through various books and articles to learn about processor caches, cache consistency, and memory barriers in the context of concurrent execution. So far though, I have been unable to determine whether a common coding practice of mine is safe in the strictest sense. Assumptions The following pseudo-code is executed on a two-processor machine: int sharedVar = 0; myThread() { print(sharedVar); } main() { sharedVar = 1; spawnThread(myThread); sleep(-1); } main() executes on processor 1 (P1), while myThread() executes on P2. Initially, sharedVar exists in the caches of both P1 and P2 with the initial value of 0 (due to some "warm-up code" that isn't shown above.) Question Strictly speaking – preferably without assuming any particular CPU – is myThread() guaranteed to print 1? With my newfound knowledge of processor caches, it seems entirely possible that at the time of the print() statement, P2 may not have received the invalidation request for sharedVar caused by P1's assignment in main(). Therefore, it seems possible that myThread() could print 0. References These are the related articles and books I've been reading. (It wouldn't allow me to format these as links because I'm a new user - sorry.) Shared Memory Consistency Models: A Tutorial hpl.hp.com/techreports/Compaq-DEC/WRL-95-7.pdf Memory Barriers: a Hardware View for Software Hackers rdrop.com/users/paulmck/scalability/paper/whymb.2009.04.05a.pdf Linux Kernel Memory Barriers kernel.org/doc/Documentation/memory-barriers.txt Computer Architecture: A Quantitative Approach amazon.com/Computer-Architecture-Quantitative-Approach-4th/dp/0123704901/ref=dp_ob_title_bk

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  • MySQL: Transactions across multiple threads

    - by Zombies
    Preliminary: I have an application which maintains a thread pool of about 100 threads. Each thread can last about 1-30 seconds before a new task replaces it. When a thread end, that thread almost always will result in inserting 1-3 records into a table, this table is used by all of the threads. Right now, no transactional support exists, but I am trying to add that now. So... Goal I want to implement a transaction for this. The rules for whether or not this transaction commits or rollback reside in the main thread. Basically there is a simple function that will return a boolean. Can I implement a transaction across multiple connections? If not, can multiple threads share the same connection? (Note: there are a LOT of inserts going on here, and that is a requirement).

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  • How can I make these images download on a seperate thread?

    - by Andy Barlow
    Hello!! I have the following code running on my Android device. It works great and displays my list items wonderfully. It's also clever in the fact it only downloads the data when it's needed by the ArrayAdapter. However, whilst the download of the thumbnail is occurring, the entire list stalls and you cannot scroll until it's finished downloading. Is there any way of threading this so it'll still scroll happily, maybe show a place holder for the downloading image, finish the download, and then show? Any help with this would be really apreciated. Thank-you kindly. Andy Barlow private class CatalogAdapter extends ArrayAdapter { private ArrayList<SingleQueueResult> items; //Must research what this actually does! public CatalogAdapter(Context context, int textViewResourceId, ArrayList<SingleQueueResult> items) { super(context, textViewResourceId, items); this.items = items; } /** This overrides the getview of the ArrayAdapter. It should send back our new custom rows for the list */ @Override public View getView(int position, View convertView, ViewGroup parent) { View v = convertView; if (v == null) { LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE); v = vi.inflate(R.layout.mylists_rows, null); } final SingleQueueResult result = items.get(position); // Sets the text inside the rows as they are scrolled by! if (result != null) { TextView title = (TextView)v.findViewById(R.id.mylist_title); TextView format = (TextView)v.findViewById(R.id.mylist_format); title.setText(result.getTitle()); format.setText(result.getThumbnail()); // Download Images ImageView myImageView = (ImageView)v.findViewById(R.id.mylist_thumbnail); downloadImage(result.getThumbnail(), myImageView); } return v; } } // This should run in a seperate thread public void downloadImage(String imageUrl, ImageView myImageView) { try { url = new URL(imageUrl); URLConnection conn = url.openConnection(); conn.connect(); InputStream is = conn.getInputStream(); BufferedInputStream bis = new BufferedInputStream(is); Bitmap bm = BitmapFactory.decodeStream(bis); bis.close(); is.close(); myImageView.setImageBitmap(bm); } catch (IOException e) { /* Reset to Default image on any error. */ //this.myImageView.setImageDrawable(getResources().getDrawable(R.drawable.default)); } }

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  • Basic Java Multi-Threading Question

    - by Veered
    When an object is instantiated in Java, is it bound to the thread that instantiated in? Because when I anonymously implement an interface in one thread, and pass it to another thread to be run, all of its methods are run in the original thread. If they are bound to their creation thread, is there anyway to create an object that will run in whatever thread calls it?

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  • C# Threads.Abort()

    - by Betamoo
    If a thread is running a function func1 that calls another function func2 inside it... Then I called thread.Abort() Will this stop func1 only OR func1 and func2 and all the functions func1 has called?? Thanks Edit: Here are more detail: func1 is called in a new thread, it continuously calls func2 on regular basis... func2 begin doing some work only if some array is not null.. it finishes it and return When supervisor wants to save data, it aborts Thread of func1- and then makes array null, saves data, then fill in the array with new one.. and starts Thread with func1 again.. Sometimes exception is raised because array is null in func2.. so func1 abort did not affect func2

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  • Spawning worker threads

    - by LB
    In C#, How would one go about spawning multiple threads and then sequentially adding results to a list before returning the entire result set? What are some best practices? I'm so far using an ManualResetEvent to signal when the last element has been processed by a thread. But when it returns, I need to have them consolidate the result sets in sequential order so that we don't get into contention issues with the return value list (total results).

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  • Windows threading: _beginthread vs _beginthreadex vs CreateThread C++

    - by Lirik
    What's a better way to start a thread? I'm trying to determine what are the advantages/disadvantages of _beginthread, _beginthreadex and CreateThread. All of these functions return a thread handle to a newly created thread, I already know that CreateThread provides a little extra information when an error occurs (it can be checked by calling GetLastError)... but what are some things I should consider when I'm using these functions? I'm working with a windows application, so cross-platform computability is already out of the question. I have gone through the msdn documentation and I just can't understand, for example, why anybody would decide to use _beginthread instead of CreateThread or vice versa. Cheers! Update: OK, thanks for all the info, I've also read in a couple of places that I can't call WaitForSingleObject() if I used _beginthread(), but if I call _endthread() in the thread shouldn't that work? What's the deal there?

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  • WaitForSingleObject( )

    - by Rakesh Agarwal
    I have got myself stuck into a really amazing issue here.The code is like as below. class A { public: A(){ m_event = CreateEvent(NULL, false, false, NULL); // create an event with initial value as non-signalled m_thread = _beginthread(StaticThreadEntry, 0, this); // create a thread } static void StaticThreadEntry(A * obj) { obj->ThreadEntry(); } void ThreadEntry(); }; void A::ThreadEntry() { WaitforSingleObject(m_event,INFINITE); } int main() { A a; SetEvent(m_event); // sets the event to signalled state which causes the running thread to terminate WaitForSingleObject(m_thread, INFINITE); // waits for the thread to terminate return 0; } Problem : When the above code is run,sometimes( 1 out of 5 ) it hangs and the control gets stuck in the call to WaitforSingleObject()( inside the main function ).The code always calls SetEvent() function to ensure that the thread would terminate before calling Wait() function. I do not see any reason why it should ever hang?

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  • Swing: what to do when a JTree update takes too long and freezes other GUI elements?

    - by java.is.for.desktop
    Hello, everyone! I know that GUI code in Java Swing must be put inside SwingUtilities.invokeAndWait or SwingUtilities.invokeLater. This way threading works fine. Sadly, in my situation, the GUI update it that thing which takes much longer than background thread(s). More specific: I update a JTree with about just 400 entries, nesting depth is maximum 4, so should be nothing scary, right? But it takes sometimes one second! I need to ensure that the user is able to type in a JTextPane without delays. Well, guess what, the slow JTree updates do cause delays for JTextPane during input. It refreshes only as soon as the tree gets updated. I am using Netbeans and know empirically that a Java app can update lots of information without freezing the rest of the UI. How can it be done? NOTE 1: All those DefaultMutableTreeNodes are prepared outside the invokeAndWait. NOTE 2: When I replace invokeAndWait with invokeLater the tree doesn't get updated. NOTE 3: Fond out that recursive tree expansion takes far the most time. NOTE 4: I'm using custom tree cell renderer, will try without and report. NOTE 4a: My tree cell renderer uses a map to cache and reuse created JTextComponents, depending on tree node (as a key). CLUE 1: Wow! Without setting custom cell renderer it's 10 times faster. I think, I'll need few good tutorials on writing custom tree cell renderers.

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  • Multiple threads modifying a collection in Java??

    - by posdef
    Hi, The project I am working on requires a whole bunch of queries towards a database. In principle there are two types of queries I am using: read from excel file, check for a couple of parameters and do a query for hits in the database. These hits are then registered as a series of custom classes. Any hit may (and most likely will) occur more than once so this part of the code checks and updates the occurrence in a custom list implementation that extends ArrayList. for each hit found, do a detail query and parse the output, so that the classes created in (I) get detailed info. I figured I would use multiple threads to optimize time-wise. However I can't really come up with a good way to solve the problem that occurs with the collection these items are stored in. To elaborate a little bit; throughout the execution objects are supposed to be modified by both (I) and (II). I deliberately didn't c/p any code, as it would be big chunks of code to make any sense.. I hope it make some sense with the description above. Thanks,

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  • Testing a Non-blocking Queue

    - by jsw
    I've ported the non-blocking queue psuedocode here to C#. The code below is meant as a near verbatim copy of the paper. What approach would you take to test the implementation? Note: I'm running in VS2010 so I don't have CHESS support yet. using System.Threading; #pragma warning disable 0420 namespace ConcurrentCollections { class QueueNodePointer<T> { internal QueueNode<T> ptr; internal QueueNodePointer() : this(null) { } internal QueueNodePointer(QueueNode<T> ptr) { this.ptr = ptr; } } class QueueNode<T> { internal T value; internal QueueNodePointer<T> next; internal QueueNode() : this(default(T)) { } internal QueueNode(T value) { this.value = value; this.next = new QueueNodePointer<T>(); } } public class ConcurrentQueue<T> { private volatile int count = 0; private QueueNodePointer<T> qhead = new QueueNodePointer<T>(); private QueueNodePointer<T> qtail = new QueueNodePointer<T>(); public ConcurrentQueue() { var node = new QueueNode<T>(); node.next.ptr = null; this.qhead.ptr = this.qtail.ptr = node; } public int Count { get { return this.count; } } public void Enqueue(T value) { var node = new QueueNode<T>(value); node.next.ptr = null; QueueNodePointer<T> tail; QueueNodePointer<T> next; while (true) { tail = this.qtail; next = tail.ptr.next; if (tail == this.qtail) { if (next.ptr == null) { var newtail = new QueueNodePointer<T>(node); if (Interlocked.CompareExchange(ref tail.ptr.next, newtail, next) == next) { Interlocked.Increment(ref this.count); break; } else { Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(next.ptr), tail); } } } } Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(node), tail); } public T Dequeue() { T value; while (true) { var head = this.qhead; var tail = this.qtail; var next = head.ptr.next; if (head == this.qhead) { if (head.ptr == tail.ptr) { if (next.ptr == null) { return default(T); } Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(next.ptr), tail); } else { value = next.ptr.value; var newhead = new QueueNodePointer<T>(next.ptr); if (Interlocked.CompareExchange(ref this.qhead, newhead, head) == head) { Interlocked.Decrement(ref this.count); break; } } } } return value; } } } #pragma warning restore 0420

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  • C# Threading vs single thread

    - by user177883
    Is it always guaranteed that a multi-threaded application would run faster than a single threaded application? I have two threads that populates data from a data source but different entities (eg: database, from two different tables), seems like single threaded version of the application is running faster than the version with two threads. Why would the reason be? when i look at the performance monitor, both cpu s are very spikey ? is this due to context switching? what are the best practices to jack the CPU and fully utilize it? I hope this is not ambiguous.

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  • Is I/O Completion ports(Windows) or Asynchronous I/O (AIO) will improve performance of multithreaded

    - by Naga
    Hi, I want to use I/O Completion ports for Windows and Asynchronous I/O (AIO) for solaris and Linux versions of my server application. The application server is multithreaded and it can accept lot of concurrent TCP connections and can process many requests per conenction. Every request will be handled by seperate detached thread. Is this criteria well enough to use the latest AIO?. Is there any standardization using which one code can be used to all platforms. Thanks, Naga

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  • Why can't I use an Action to a ThreadStart?

    - by Rookian
    Both are delegates and have the same signature, but I can not use Action as ThreadStart. Why? Action doIt; doIt = () => MyMethod("test"); Thread t; t = new Thread(doIt); t.Start(); but this seams to work: Thread t; t = new Thread(() => MyMethod("test")); t.Start();

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  • Is SynchronizationContext.Post() threadsafe?

    - by cyclotis04
    This is a pretty basic question, and I imagine that it is, but I can't find any definitive answer. Is SynchronizationContext.Post() threadsafe? I have a member variable which holds the main thread's context, and _context.Post() is being called from multiple threads. I imagine that Post() could be called simultaneously on the object. Should I do something like lock (_contextLock) _context.Post(myDelegate, myEventArgs); or is that unnecessary? Edit: MSDN states that "Any instance members are not guaranteed to be thread safe." Should I keep my lock(), then?

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  • Help with java executors: wait for task termination.

    - by Raffo
    I need to submit a number of task and then wait for them until all results are available. Each of them adds a String to a Vector (that is synchronized by default). Then I need to start a new task for each result in the Vector but I need to do this only when all the previous tasks have stopped doing their job. I want to use Java Executor, in particular I tried using Executors.newFixedThreadPool(100) in order to use a fixed number of thread (I have a variable number of task that can be 10 or 500) but I'm new with executors and I don't know how to wait for task termination. This is something like a pseudocode of what my program needs to do: EecutorService e = Executors.newFixedThreadPool(100); while(true){ /*do something*/ for(...){ <start task> } <wait for all task termination> for each String in result{ <start task> } <wait for all task termination> } I can't do a e.shutdown because I'm in a while(true) and I need to reuse the executorService... Can you help me? Can you suggest me a guide/book about java executors??

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  • SQLite multi process access

    - by Nicolas
    Hello, We are using SQLite in a multi processes and multi threaded application. The SQLite database files are encrypted using the embedded SQLite encryption. The FAQ states that SQLite should be able to manage multi process accesses using locks mechanism. We are experiencing a strange problem: When many threads are accessing the same database file, sometime constrains violations occur, more specifically - a field with a unique constrain is getting duplicate values after calling "insert or replace" statement. It happens quite often now, that we are using the encryption. Before we started using SQLite encryption we did not notice such a behavior. Are there any specific known issues with this?

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  • Thread.CurrentThread.CurrentUICulture not working consistently

    - by xTRUMANx
    I've been working on a pet project on the weekends to learn more about C# and have encountered an odd problem when working with localization. To be more specific, the problem I have is with System.Threading.Thread.CurrentThread.CurrentUICulture. I've set up my app so that the user can quickly change the language of the app by clicking a menu item. The menu item in turn, saves the two-letter code for the language (e.g. "en", "fr", etc.) in a user setting called 'Language' and then restarts the application. Properties.Settings.Default.Language = "en"; Properties.Settings.Default.Save(); Application.Restart(); When the application is started up, the first line of code in the Form's constructor (even before InitializeComponent()) fetches the Language string from the settings and sets the CurrentUICulture like so: public Form1() { Thread.CurrentThread.CurrentUICulture = new CultureInfo(Properties.Settings.Default.Language); InitializeComponent(); } The thing is, this doesn't work consistently. Sometimes, all works well and the application loads the correct language based on the string saved in the settings file. Other times, it doesn't, and the language remains the same after the application is restarted. At first I thought that I didn't save the language before restarting the application but that is definitely not the case. When the correct language fails to load, if I were to close the application and run it again, the correct language would come up correctly. So this implies that the Language string has been saved but the CurrentUICulture assignment in my form constructor is having no effect sometimes. Any help? Is there something I'm missing of how threading works in C#? This could be machine-specific, so if it makes any difference I'm using Pentium Dual-Core CPU. UPDATE Vlad asked me to check what the CurrentThread's CurrentUICulture is. So I added a MessageBox on my constructor to tell me what the CurrentUICulture two-letter code is as well as the value of my Language user string. MessageBox.Show(string.Format("Current Language: {0}\nCurrent UI Culture: {1}", Properties.Settings.Default.Language, Thread.CurrentThread.CurrentUICulture.TwoLetterISOLanguageName)); When the wrong language is loaded, both the Language string and CurrentUICulture have the wrong language. So I guess the CurrentUICulture has been cleared and my problem is actually with the Language Setting. So I guess the problem is that my application sometimes loads the previously saved language string rather than the last saved language string. If the app is restarted, it will then load the actual saved language string.

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  • MySQLdb not INSERTING, _mysql does fine.

    - by Mad_Casual
    Okay, I log onto the MySQL command-line client as root. I then open or otherwise run a python app using the MySQLdb module as root. When I check the results using python (IDLE), everything looks fine. When I use the MySQL command-line client, no INSERT has occurred. If I change things around to _mysql instead of MySQLdb, everything works fine. I'd appreciate any clarification(s). "Works" until IDLE/Virtual machine is reset: <pre><code>import MySQLdb db = MySQLdb.connect(user='root', passwd='*******',db='test') cursor = db.cursor() cursor.execute("""INSERT INTO test VALUES ('somevalue');""",)</code></end> Works: <pre><code>import _mysql db = _mysql.connect(user='root', passwd='*******',db='test') db.query("INSERT INTO test VALUES ('somevalue');")</code></end> System info: Intel x86 WinXP Python 2.5 MySQL 5.1.41 MySQL-Python 1.2.2

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