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• Memory Bandwidth Performance for Modern Machines

  - by porgarmingduod

  I'm designing a real-time system that occasionally has to duplicate a large amount of memory. The memory consists of non-tiny regions, so I expect the copying performance will be fairly close to the maximum bandwidth the relevant components (CPU, RAM, MB) can do. This led me to wonder what kind of raw memory bandwidth modern commodity machine can muster? My aging Core2Duo gives me 1.5 GB/s if I use 1 thread to memcpy() (and understandably less if I memcpy() with both cores simultaneously.) While 1.5 GB is a fair amount of data, the real-time application I'm working on will have have something like 1/50th of a second, which means 30 MB. Basically, almost nothing. And perhaps worst of all, as I add multiple cores, I can process a lot more data without any increased performance for the needed duplication step. But a low-end Core2Due isn't exactly hot stuff these days. Are there any sites with information, such as actual benchmarks, on raw memory bandwidth on current and near-future hardware? Furthermore, for duplicating large amounts of data in memory, are there any shortcuts, or is memcpy() as good as it will get? Given a bunch of cores with nothing to do but duplicate as much memory as possible in a short amount of time, what's the best I can do?

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• Bash: how to simply parallelize tasks?

  - by NoozNooz42

  I'm writing a tiny script that calls the "PNGOUT" util on a few hundred PNG files. I simply did this: find $BASEDIR -iname "*png" -exec pngout {} \; And then I looked at my CPU monitor and noticed only one of the core was used, which is quite sad. In this day and age of dual, quad, octo and hexa (?) cores desktop, how do I simply parallelize this task with Bash? (it's not the first time I've had such a need, for quite a lot of these utils are mono-threaded... I already had the case with mp3 encoders). Would simply running all the pngout in the background do? How would my find command look like then? (I'm not too sure how to mix find and the '&' character) I if have three hundreds pictures, this would mean swapping between three hundreds processes, which doesn't seem great anyway!? Or should I copy my three hundreds files or so in "nb dirs", where "nb dirs" would be the number of cores, then run concurrently "nb finds"? (which would be close enough) But how would I do this?

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• C & MinGW: Hello World gives me the error "programm too big to fit in memory"

  - by user1692088

  I'm new here. Here's my problem: I installed MinGW on my Windows 7 Home Premium 32-bit Netbook with Intel Atom CPU N550, 1.50GHz and 2GB RAM. Now I made a file named hello.h and tried to compile it via CMD with the following command: "gcc c:\workspace\c\helloworld\hello.h -o out.exe" It compiles with no error, but when I try to run out.exe, it gives me following error: "program too big to fit in memory" Things I have checked: I have added "C:\MinGW\bin" to the Windows PATH Variable I have googled for about one hour, but ever since I'm a newbie, I can't really figure out what the problem is. I have compiled the same code on my 64-bit machine, compiles perfectly, but cannot be run due to 64-bit <- 16-bit problematic. I'd really appreciate, if someone could figure out, what the problem is. Btw, here's my hello.h: #include <stdio.h> int main(void){ printf("Hello, World\n"); } ... That's it. Thanks for your replies. Cheers, Boris

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• Which linear programming package should I use for high numbers of constraints and "warm starts"

  - by davidsd

  I have a "continuous" linear programming problem that involves maximizing a linear function over a curved convex space. In typical LP problems, the convex space is a polytope, but in this case the convex space is piecewise curved -- that is, it has faces, edges, and vertices, but the edges aren't straight and the faces aren't flat. Instead of being specified by a finite number of linear inequalities, I have a continuously infinite number. I'm currently dealing with this by approximating the surface by a polytope, which means discretizing the continuously infinite constraints into a very large finite number of constraints. I'm also in the situation where I'd like to know how the answer changes under small perturbations to the underlying problem. Thus, I'd like to be able to supply an initial condition to the solver based on a nearby solution. I believe this capability is called a "warm start." Can someone help me distinguish between the various LP packages out there? I'm not so concerned with user-friendliness as speed (for large numbers of constraints), high-precision arithmetic, and warm starts. Thanks!

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• How to terminate all [grand]child processes using C# on WXP (and newer MSWindows)

  - by NVRAM

  Question: How can I determine all processes in the child's Process Tree to kill them? I have an application, written in C# that will: Get a set of data from the server, Spawn a 3rd party utility to process the data, then Return the results to the server. This is working fine. But since a run consumes a lot of CPU and may take as long as an hour, I want to add the ability to have my app terminate its child processes. Some issues that make the simple solutions I've found elsewhere are: My app's child process "A" (InstallAnywhere EXE I think) spawns the real processing app "B" (a java.exe), which in turns spawns more children "C1".."Cn" (most of which are also written in Java). There will likely be multiple copies of my application (and hence, multiple sets of its children) running on the same machine. The child process is not in my control so there might be some "D" processes in the future. My application must run on 32-bit and 64-bit versions of MSWindows. On the plus side there is no issue of data loss, a "clean" shutdown doesn't matter as long as the processes end fairly quickly.

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• A map and set which uses contiguous memory and has a reserve function

  - by edA-qa mort-ora-y

  I use several maps and sets. The lack of contiguous memory, and high number of (de)allocations, is a performance bottleneck. I need a mainly STL-compatbile map and set class which can use a contiguous block of memory for internal objects (or multiple blocks). It also needs to have a reserve function so that I can preallocate for expected sizes. Before I write my own I'd like to check what is available first. Is there something in Boost which does this? Does somebody know of an available implementation elsewhere? Intrusive collection types are not usable here as the same objects need to exist in several collections. As far as I know STL memory pools are per-type, not per instance. These global pools are not efficient with respect to memory locality in mutli-cpu/core processing. Object pools don't work as the types will be shared between instance but their pool should not. In many cases a hash map may be an option in some cases.

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• Is there a PHP benchmark that meets these specific criteria? [closed]

  - by Alex R

  I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The PHP source needs to be in a single file. It should solve a real-world problem. No silly looping over empty methods etc. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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• learning to type - tips for programmers?

  - by OrbMan

  After hunting and pecking for about 35 years, I have decided to learn to type. I am learning QWERTY and have learned about 2/3 of the letters so far. While learning, I have noticed how asymmeterical the keyboard is, which really bothers me. (I will probably switch to a symmetrical keyboard eventually, but for now am trying to do everything as standard and "correct" as possible.) Although I am not there yet in my lessons, it seems that many of the keys I am going to use as a C# web developer are supposed to be typed by the pinky of my right hand. Are there any typing patterns you have developed that are more ergonomic (or faster) when typing large volumes of code rife with braces, colons, semi-colons and quotes? Or, should I just accept the fact that every other key is going to be hit with my right pinky? It is not that speed is such a huge concern, as much as that it seems so inefficient to rely on one finger so much... As an example, some of the conventions I use as a hunt and pecker, like typing open and close braces right away with my index and middle finger, and then hitting the left arrow key to fill in the inner content, don't seem to work as well with just a pinky. What are some typing patterns using a standard QWERTY keyboard that work really well for you as a programmer?

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• UpdateAllViews() from within a worker thread?

  - by Harvey

  I have a worker thread in a class that is owned by a ChildView. (I intend to move this to the Doc eventually.) When the worker thread completes a task I want all the views to be updated. How can I make a call to tell the Doc to issue an UpdateAllViews()? Or is there a better approach? Thank you. Added by OP: I am looking for a simple solution. The App is running on a single user, single CPU computer and does not need network (or Internet) access. There is nothing to cause a deadlock. I think I would like to have the worker thread post (or send) a message to cause the views to update. Everything I read about threading seems way more complicated than what I need - and, yes, I understand that all those precautions are necessary for applications that are running in multiprocessor, multiuser, client-server systems, etc. But none of those apply in my situation. I am just stuck at getting the right combination of getting the window handle, posting the message and responding to the message in the right functions and classes to compile and function at all.

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• SQL Server lock/hang issue

  - by mattwoberts

  Hi, I'm using SQL Server 2008 on Windows Server 2008 R2, all sp'd up. I'm getting occasional issues with SQL Server hanging with the CPU usage on 100% on our live server. It seems all the wait time on SQL Sever when this happens is given to SOS_SCHEDULER_YIELD. Here is the Stored Proc that causes the hang. I've added the "WITH (NOLOCK)" in an attempt to fix what seems to be a locking issue. ALTER PROCEDURE [dbo].[MostPopularRead] AS BEGIN SET NOCOUNT ON; SELECT c.ForeignId , ct.ContentSource as ContentSource , sum(ch.HitCount * hw.Weight) as Popularity , (sum(ch.HitCount * hw.Weight) * 100) / @Total as Percent , @Total as TotalHits from ContentHit ch WITH (NOLOCK) join [Content] c WITH (NOLOCK) on ch.ContentId = c.ContentId join HitWeight hw WITH (NOLOCK) on ch.HitWeightId = hw.HitWeightId join ContentType ct WITH (NOLOCK) on c.ContentTypeId = ct.ContentTypeId where ch.CreatedDate between @Then and @Now group by c.ForeignId , ct.ContentSource order by sum(ch.HitCount * hw.HitWeightMultiplier) desc END The stored proc reads from the table "ContentHit", which is a table that tracks when content on the site is clicked (it gets hit quite frequently - anything from 4 to 20 hits a minute). So its pretty clear that this table is the source of the problem. There is a stored proc that is called to add hit tracks to the ContentHit table, its pretty trivial, it just builds up a string from the params passed in, which involves a few selects from some lookup tables, followed by the main insert: BEGIN TRAN insert into [ContentHit] (ContentId, HitCount, HitWeightId, ContentHitComment) values (@ContentId, isnull(@HitCount,1), isnull(@HitWeightId,1), @ContentHitComment) COMMIT TRAN The ContentHit table has a clustered index on its ID column, and I've added another index on CreatedDate since that is used in the select. When I profile the issue, I see the Stored proc executes for exactly 30 seconds, then the SQL timeout exception occurs. If it makes a difference the web application using it is ASP.NET, and I'm using Subsonic (3) to execute these stored procs. Can someone please advise how best I can solve this problem? I don't care about reading dirty data... Thanks

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• ADO/SQL Server: What is the error code for "timeout expired"?

  - by Ian Boyd

  i'm trying to trap a "timeout expired" error from ADO. When a timeout happens, ADO returns: Number: 0x80040E31 (DB_E_ABORTLIMITREACHED in oledberr.h) SQLState: HYT00 NativeError: 0 The NativeError of zero makes sense, since the timeout is not a function of the database engine (i.e. SQL Server), but of ADO's internal timeout mechanism. The Number (i.e. the COM hresult) looks useful, but the definition of DB_E_ABORTLIMITREACHED in oledberr.h says: Execution stopped because a resource limit was reached. No results were returned. This error could apply to things besides "timeout expired" (some potentially server-side), such as a governor that limits: CPU usage I/O reads/writes network bandwidth and stops a query. The final useful piece is SQLState, which is a database-independent error code system. Unfortunately the only reference for SQLState error codes i can find have no mention of HYT00. What to do? What do do? Note: i can't trust 0x80040E31 (DB_E_ABORTLIMITREACHED) to mean "timeout expired", anymore than i could trust 0x80004005 (E_UNSPECIFIED_ERROR) to mean "Transaction was deadlocked on lock resources with another process and has been chosen as the deadlock victim". My pseudo-question becomes: does anyone have documentation on what the SQLState "HYT000" means? And my real question still remains: How can i specifically trap an ADO timeout expired exception thrown by ADO? Gotta love the questions where the developer is trying to "do the right thing", but nobody knows how to do the right thing. Also gotta love how googling for DB_E_ABORTLIMITREACHED and this question is #9, with MSDN nowhere to be found. Update 3 From the OLEdb ICommand.Execute reference: DB_E_ABORTLIMITREACHED Execution has been aborted because a resource limit has been reached. For example, a query timed out. No results have been returned. "For example", meaning not an exhaustive list.

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• Dragging an UIView inside UIScrollView

  - by Sergey Mikhanov

  Hello community! I am trying to solve a basic problem with drag and drop on iPhone. Here's my setup: I have a UIScrollView which has one large content subview (I'm able to scroll and zoom it) Content subview has several small tiles as subviews that should be dragged around inside it. My UIScrollView subclass has this method: - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event { UIView *tile = [contentView pointInsideTiles:[self convertPoint:point toView:contentView] withEvent:event]; if (tile) { return tile; } else { return [super hitTest:point withEvent:event]; } } Content subview has this method: - (UIView *)pointInsideTiles:(CGPoint)point withEvent:(UIEvent *)event { for (TileView *tile in tiles) { if ([tile pointInside:[self convertPoint:point toView:tile] withEvent:event]) return tile; } return nil; } And tile view has this method: - (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event { UITouch *touch = [touches anyObject]; CGPoint location = [touch locationInView:self.superview]; self.center = location; } This works, but not fully correct: the tile sometimes "falls down" during the drag process. More precisely, it stops receiving touchesMoved: invocations, and scroll view starts scrolling instead. I noticed that this depends on the drag speed: the faster I drag, the quicker the tile "falls". Any ideas on how to keep the tile glued to the dragging finger? Thanks in advance!

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• Best Practice - Removing item from generic collection in C#

  - by Matt Davis

  I'm using C# in Visual Studio 2008 with .NET 3.5. I have a generic dictionary that maps types of events to a generic list of subscribers. A subscriber can be subscribed to more than one event. private static Dictionary<EventType, List<ISubscriber>> _subscriptions; To remove a subscriber from the subscription list, I can use either of these two options. Option 1: ISubscriber subscriber; // defined elsewhere foreach (EventType event in _subscriptions.Keys) { if (_subscriptions[event].Contains(subscriber)) { _subscriptions[event].Remove(subscriber); } } Option 2: ISubscriber subscriber; // defined elsewhere foreach (EventType event in _subscriptions.Keys) { _subscriptions[event].Remove(subscriber); } I have two questions. First, notice that Option 1 checks for existence before removing the item, while Option 2 uses a brute force removal since Remove() does not throw an exception. Of these two, which is the preferred, "best-practice" way to do this? Second, is there another, "cleaner," more elegant way to do this, perhaps with a lambda expression or using a LINQ extension? I'm still getting acclimated to these two features. Thanks. EDIT Just to clarify, I realize that the choice between Options 1 and 2 is a choice of speed (Option 2) versus maintainability (Option 1). In this particular case, I'm not necessarily trying to optimize the code, although that is certainly a worthy consideration. What I'm trying to understand is if there is a generally well-established practice for doing this. If not, which option would you use in your own code?

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• Link checker ; how to avoid false positives

  - by Burnzy

  I'm working a on a link checker/broken link finder and I am getting many false positives, after double checking I noticed that many error codes were returning webexceptions but they were actually downloadable, but in some other cases the statuscode is 404 and i can access the page from the browse. So here is the code, its pretty ugly, and id like to have something more, id say practical. All the status codes are in that big if are used to filter the ones i dont want to add to brokenlink because they are valid links ( i tested them all ). What i need to fix is the structure (if possible) and how to not get false 404. Thank you! try { HttpWebRequest request = ( HttpWebRequest ) WebRequest.Create ( uri ); request.Method = "Head"; request.MaximumResponseHeadersLength = 32; // FOR IE SLOW SPEED request.AllowAutoRedirect = true; using ( HttpWebResponse response = ( HttpWebResponse ) request.GetResponse() ) { request.Abort(); } /* WebClient wc = new WebClient(); wc.DownloadString( uri ); */ _validlinks.Add ( strUri ); } catch ( WebException wex ) { if ( !wex.Message.Contains ( "The remote name could not be resolved:" ) && wex.Status != WebExceptionStatus.ServerProtocolViolation ) { if ( wex.Status != WebExceptionStatus.Timeout ) { HttpStatusCode code = ( ( HttpWebResponse ) wex.Response ).StatusCode; if ( code != HttpStatusCode.OK && code != HttpStatusCode.BadRequest && code != HttpStatusCode.Accepted && code != HttpStatusCode.InternalServerError && code != HttpStatusCode.Forbidden && code != HttpStatusCode.Redirect && code != HttpStatusCode.Found ) { _brokenlinks.Add ( new Href ( new Uri ( strUri , UriKind.RelativeOrAbsolute ) , UrlType.External ) ); } else _validlinks.Add ( strUri ); } else _brokenlinks.Add ( new Href ( new Uri ( strUri , UriKind.RelativeOrAbsolute ) , UrlType.External ) ); } else _validlinks.Add ( strUri ); }

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• Fetching real time data from excel

  - by Umesh Sharma

  I am seriouly looking for your valuable help first time here. If possible, plese help me. I am developing a VB.NET app in which i read "real time data" from a excel sheet using "Microsoft.Office.Interop.Excel" i.e. excel automation. All cells in excel sheet are fetching stock data from some LOCAL DDE Server like "=XYZ|Bid!GOLD", "=XYZ|Bid!SILVER", "=XYZ|Ask!SILVER" and so on... Some cells also having fixed values like "Symbol", "Bid Rate", "32.90" etc. Values of DDE mapped cells (i.e. =XYZ|xxxx!yyy) are continuously changing. THE PROBLEM is here..."FIXED values" from excel cells are coming quite ok to my app but all DDE mapped cells values are coming "-2146826246" (When datasource local dde server ON) or "-2146826265" (OFF). Although, if i use C#.NET, it's all ok but not with Vb.NET. I want to display range of excel (A1 to J50) into VB.NET ListView which are changing in every 200ms (5 times in every 1 second) ================ Important ====================================================== Is it possible to BIND "listview items/columns values" with "excel cells" or some local memory variables ?? Currently, i am reading excel "cell by cell" and trying to put values in .NET listview but CPU USES are very high as well as it's toooo slow process. If yes, then how please ? I am a VFP developer but new to .NET It's very easy in VFP then why not in .NET ?? Please guide me, if someone has the solution...

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• SQL Server insert performance

  - by Jose

  I have an insert query that gets generated like this INSERT INTO InvoiceDetail (LegacyId,InvoiceId,DetailTypeId,Fee,FeeTax,Investigatorid,SalespersonId,CreateDate,CreatedById,IsChargeBack,Expense,RepoAgentId,PayeeName,ExpensePaymentId,AdjustDetailId) VALUES(1,1,2,1500.0000,0.0000,163,1002,'11/30/2001 12:00:00 AM',1116,0,550.0000,850,NULL,@ExpensePay1,NULL); DECLARE @InvDetail1 INT; SET @InvDetail1 = (SELECT @@IDENTITY); This query is generated for only 110K rows. It takes 30 minutes for all of these query's to execute I checked the query plan and the largest % nodes are A Clustered Index Insert at 57% query cost which has a long xml that I don't want to post. A Table Spool which is 38% query cost <RelOp AvgRowSize="35" EstimateCPU="5.01038E-05" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimateRows="1" LogicalOp="Eager Spool" NodeId="80" Parallel="false" PhysicalOp="Table Spool" EstimatedTotalSubtreeCost="0.0466109"> <OutputList> <ColumnReference Database="[SkipPro]" Schema="[dbo]" Table="[InvoiceDetail]" Column="InvoiceId" /> <ColumnReference Database="[SkipPro]" Schema="[dbo]" Table="[InvoiceDetail]" Column="InvestigatorId" /> <ColumnReference Column="Expr1054" /> <ColumnReference Column="Expr1055" /> </OutputList> <Spool PrimaryNodeId="3" /> </RelOp> So my question is what is there that I can do to improve the speed of this thing? I already run ALTER TABLE TABLENAME NOCHECK CONSTRAINTS ALL Before the queries and then ALTER TABLE TABLENAME NOCHECK CONSTRAINTS ALL after the queries. And that didn't shave off hardly anything off of the time. Know I am running these queries in a .NET application that uses a SqlCommand object to send the query. I then tried to output the sql commands to a file and then execute it using sqlcmd, but I wasn't getting any updates on how it was doing, so I gave up on that. Any ideas or hints or help?

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• Why is curl in Ruby slower than command-line curl?

  - by Stiivi

  I am trying to download more than 1m pages (URLs ending by a sequence ID). I have implemented kind of multi-purpose download manager with configurable number of download threads and one processing thread. The downloader downloads files in batches: curl = Curl::Easy.new batch_urls.each { |url_info| curl.url = url_info[:url] curl.perform file = File.new(url_info[:file], "wb") file << curl.body_str file.close # ... some other stuff } I have tried to download 8000 pages sample. When using the code above, I get 1000 in 2 minutes. When I write all URLs into a file and do in shell: cat list | xargs curl I gen all 8000 pages in two minutes. Thing is, I need it to have it in ruby code, because there is other monitoring and processing code. I have tried: Curl::Multi - it is somehow faster, but misses 50-90% of files (does not download them and gives no reason/code) multiple threads with Curl::Easy - around the same speed as single threaded Why is reused Curl::Easy slower than subsequent command line curl calls and how can I make it faster? Or what I am doing wrong? I would prefer to fix my download manager code than to make downloading for this case in a different way. Before this, I was calling command-line wget which I provided with a file with list of URLs. Howerver, not all errors were handled, also it was not possible to specify output file for each URL separately when using URL list. Now it seems to me that the best way would be to use multiple threads with system call to 'curl' command. But why when I can use directly Curl in Ruby? Code for the download manager is here, if it might help: Download Manager (I have played with timeouts, from not-setting it to various values, it did not seem help) Any hints appreciated.

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• Why is cell phone software is still so primitive?

  - by Tomislav Nakic-Alfirevic

  I don't do mobile development, but it strikes me as odd that features like this aren't available by default on most phones: full text search: searches all address book contents, messages, anything else being a plus better call management: e.g. a rotating audio call log, meaning you always have the last N calls recorded for your listening pleasure later (your little girl just said her first "da-da" while you were on a business trip, you had a telephone job interview, you received complex instructions to do something etc.) bluetooth remote control (like e.g. anyRemote, but available by default on a bluetooth phone) no multitasking capabilities worth mentioning and in general no e.g. weekly software updates, making the phone much more usable (even if it had to be done over USB, rather than over the network). I'm sure I was dumbfounded by the lack or design of other features as well, but they don't come to mind right now. To clarify, I'm not talking about smartphones here: my plain, 2-year old phone has a CPU an order of magnitude faster than my first PC, about as much storage space and it's ridiculous how bad (slow, unwieldy) the software is and it's not one phone or one manufacturer. What keeps the (to me) obvious software functionality vacuum on a capable hardware platform from being filled up?

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• Why is VB6 still so widely used?

  - by Uri

  Note that this question is not meant to start an argument, I am genuinely curious: Back in the 90s I used to work for a large CPU maker and we were building some debuggers. All our core logic was in C++, but the GUI was made in VB6. We couldn't figure out MFC and it was too much a hassle. We glued together VB6 and C++ using COM which we created via ATL. Fast forward to 2009, having been mostly in the Java world I am looking at job boards and seeing more VB6 jobs than I expected. I genuinely thought that VB6 was extinct, especially since VB.NET supposedly solved a lot of the problems with the VB6 which at the time felt a lot like a scripting language than a true OOP language. So what happened? Why is new code still written in it? Isn't there a better way to glue C++ and VB.NET? Note that I haven't used VB.NET, I just understand that it is a much more "stricter" language than VB6 was. Even with Option Explicit or whatever it was.

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• Fastest way to generate delimited string from 1d numpy array

  - by Abiel

  I have a program which needs to turn many large one-dimensional numpy arrays of floats into delimited strings. I am finding this operation quite slow relative to the mathematical operations in my program and am wondering if there is a way to speed it up. For example, consider the following loop, which takes 100,000 random numbers in a numpy array and joins each array into a comma-delimited string. import numpy as np x = np.random.randn(100000) for i in range(100): ",".join(map(str, x)) This loop takes about 20 seconds to complete (total, not each cycle). In contrast, consider that 100 cycles of something like elementwise multiplication (x*x) would take than one 1/10 of a second to complete. Clearly the string join operation creates a large performance bottleneck; in my actual application it will dominate total runtime. This makes me wonder, is there a faster way than ",".join(map(str, x))? Since map() is where almost all the processing time occurs, this comes down to the question of whether there a faster to way convert a very large number of numbers to strings.

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• javafx doesnt repaint label till method has finished, why?

  - by jeff porter

  Hi all, I have a JavaFX app with a some code like this... public class MainListener extends EventListener{ override public function event (arg0 : String) : Void { statusText.content = arg0; } } statusText is defined like this... var statusText = Text { x: 30 y: stageHeight - 40 font: Font { name: "Bitstream Vera Sans Bold" size: 10 } wrappingWidth: 420 fill: Color.WHITE textAlignment: TextAlignment.CENTER content: "Status: awaiting DBF file." }; I also have some other Javacode that is load data, much like this.. public ArrayList<CustomerRecord> read(EventListener listener) { ArrayList<CustomerRecord> listOfCustomerRecords = new ArrayList<CustomerRecord>(); listener.event("Status: Starting read"); // ** takes a while... List<Map<String, CustomerField>> customerRecords = new Reader(file).readData(listener); // ** long running method over. listener.event("Status: Loaded all customers, count:" + listOfCustomerRecords.size()); return listOfCustomerRecords; } Now while the last method is in its long running call, I would expect to see my statusText updated to have 'Status: Starting read', but its doesn't. Its only when the read() method returns that the text is updated. If its was 'straight' java I would presume that the long running job is hogging the CPU, or the statusText needed to have repaint() called on it. Can anyone give me any ideas? Thanks Jeff Porter

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• DAL Layer : EF 4.0 or Normal Data access layer with Stored Procedure

  - by Harryboy

  Hello Experts, Application : I am working on one mid-large size application which will be used as a product, we need to decide on our DAL layer. Application UI is in Silverlight and DAL layer is going to be behind service layer. We are also moving ahead with domain model, so our DB tables and domain classes are not having same structure. So patterns like Data Mapper and Repository will definitely come into picture. I need to design DAL Layer considering below mentioned factors in priority manner Speed of Development with above average performance Maintenance Future support and stability of the technology Performance Limitation : 1) As we need to strictly go ahead with microsoft, we can not use NHibernate or any other ORM except EF 4.0 2) We can use any code generation tool (Should be Open source or very cheap) but it should only generate code in .Net, so there would not be any licensing issue on per copy basis. Questions I read so many articles about EF 4.0, on outset it looks like that it is still lacking in features from NHibernate but it is considerably better then EF 1.0 So, Do you people feel that we should go ahead with EF 4.0 or we should stick to ADO .Net and use any code geneartion tool like code smith or any other you feel best Also i need to answer questions like what time it will take to port application from EF 4.0 to ADO .Net if in future we stuck up with EF 4.0 for some features or we are having serious performance issue. In reverse case if we go ahead and choose ADO .Net then what time it will take to swith to EF 4.0 Lastly..as i was going through the article i found the code only approach (with POCO classes) seems to be best suited for our requirement as switching is really easy from one technology to other. Please share your thoughts on the same and please guide on the above questions

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• Which is the best jQuery-powered site?

  - by Reigel

  This "Top 10 JavaScript (jQuery) Powered Sites", posted about 2 years ago, was the one that invites me(after seeing the list) to use jQuery. All the sites in that list made me realize how cool it is to build sites powered by jQuery. And now more and more sites are being powered by jQuery. More and more developers are learning jQuery. Two years have past now but I still do a search to google for best sites and still got me to that link and which the link is not updated from the first time I have looked at it. Here at stackoverflow, there are lots of jQuery user. I was thinking if we can here show some of the sites that you know that is powered by jQuery which you think is best. If you can, please make it one site one answer, so that we can make a vote if it's really best jQuery powered site. We will take a look if it is really well implemented ( the way the codes are written, fast speed site, etc...) and deserves to be the best. Lot's of viewers will benefit from it. Like, we can view and have an idea of how we will make our next project cooler, faster, and powerful.

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• Use a vector to index a matrix without linear index

  - by David_G

  G'day, I'm trying to find a way to use a vector of [x,y] points to index from a large matrix in MATLAB. Usually, I would convert the subscript points to the linear index of the matrix.(for eg. Use a vector as an index to a matrix in MATLab) However, the matrix is 4-dimensional, and I want to take all of the elements of the 3rd and 4th dimensions that have the same 1st and 2nd dimension. Let me hopefully demonstrate with an example: Matrix = nan(4,4,2,2); % where the dimensions are (x,y,depth,time) Matrix(1,2,:,:) = 999; % note that this value could change in depth (3rd dim) and time (4th time) Matrix(3,4,:,:) = 888; % note that this value could change in depth (3rd dim) and time (4th time) Matrix(4,4,:,:) = 124; Now, I want to be able to index with the subscripts (1,2) and (3,4), etc and return not only the 999 and 888 which exist in Matrix(:,:,1,1) but the contents which exist at Matrix(:,:,1,2),Matrix(:,:,2,1) and Matrix(:,:,2,2), and so on (IRL, the dimensions of Matrix might be more like size(Matrix) = (300 250 30 200) I don't want to use linear indices because I would like the results to be in a similar vector fashion. For example, I would like a result which is something like: ans(time=1) 999 888 124 999 888 124 ans(time=2) etc etc etc etc etc etc I'd also like to add that due to the size of the matrix I'm dealing with, speed is an issue here - thus why I'd like to use subscript indices to index to the data. I should also mention that (unlike this question: Accessing values using subscripts without using sub2ind) since I want all the information stored in the extra dimensions, 3 and 4, of the i and jth indices, I don't think that a slightly faster version of sub2ind still would not cut it..

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• Where is my python script spending time? Is there "missing time" in my cprofile / pstats trace?

  - by fmark

  I am attempting to profile a long running python script. The script does some spatial analysis on raster GIS data set using the gdal module. The script currently uses three files, the main script which loops over the raster pixels called find_pixel_pairs.py, a simple cache in lrucache.py and some misc classes in utils.py. I have profiled the code on a moderate sized dataset. pstats returns: p.sort_stats('cumulative').print_stats(20) Thu May 6 19:16:50 2010 phes.profile 355483738 function calls in 11644.421 CPU seconds Ordered by: cumulative time List reduced from 86 to 20 due to restriction <20> ncalls tottime percall cumtime percall filename:lineno(function) 1 0.008 0.008 11644.421 11644.421 <string>:1(<module>) 1 11064.926 11064.926 11644.413 11644.413 find_pixel_pairs.py:49(phes) 340135349 544.143 0.000 572.481 0.000 utils.py:173(extent_iterator) 8831020 18.492 0.000 18.492 0.000 {range} 231922 3.414 0.000 8.128 0.000 utils.py:152(get_block_in_bands) 142739 1.303 0.000 4.173 0.000 utils.py:97(search_extent_rect) 745181 1.936 0.000 2.500 0.000 find_pixel_pairs.py:40(is_no_data) 285478 1.801 0.000 2.271 0.000 utils.py:98(intify) 231922 1.198 0.000 2.013 0.000 utils.py:116(block_to_pixel_extent) 695766 1.990 0.000 1.990 0.000 lrucache.py:42(get) 1213166 1.265 0.000 1.265 0.000 {min} 1031737 1.034 0.000 1.034 0.000 {isinstance} 142740 0.563 0.000 0.909 0.000 utils.py:122(find_block_extent) 463844 0.611 0.000 0.611 0.000 utils.py:112(block_to_pixel_coord) 745274 0.565 0.000 0.565 0.000 {method 'append' of 'list' objects} 285478 0.346 0.000 0.346 0.000 {max} 285480 0.346 0.000 0.346 0.000 utils.py:109(pixel_coord_to_block_coord) 324 0.002 0.000 0.188 0.001 utils.py:27(__init__) 324 0.016 0.000 0.186 0.001 gdal.py:848(ReadAsArray) 1 0.000 0.000 0.160 0.160 utils.py:50(__init__) The top two calls contain the main loop - the entire analyis. The remaining calls sum to less than 625 of the 11644 seconds. Where are the remaining 11,000 seconds spent? Is it all within the main loop of find_pixel_pairs.py? If so, can I find out which lines of code are taking most of the time?

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