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• Can a large transaction log cause cpu hikes to occur

  - by Simon Rigby

  Hello all, I have a client with a very large database on Sql Server 2005. The total space allocated to the db is 15Gb with roughly 5Gb to the db and 10 Gb to the transaction log. Just recently a web application that is connecting to that db is timing out. I have traced the actions on the web page and examined the queries that execute whilst these web operation are performed. There is nothing untoward in the execution plan. The query itself used multiple joins but completes very quickly. However, the db server's CPU hikes to 100% for a few seconds. The issue occurs when several simultaneous users are working on the system (when I say multiple .. read about 5). Under this timeouts start to occur. I suppose my question is, can a large transaction log cause issues with CPU performance? There is about 12Gb of free space on the disk currently. The configuration is a little out of my hands but the db and log are both on the same physical disk. I appreciate that the log file is massive and needs attending to, but I'm just looking for a heads up as to whether this may cause CPU spikes (ie trying to find the correlation). The timeouts are a recent thing and this app has been responsive for a few years (ie its a recent manifestation). Many Thanks,

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• Function returning dictionary, not seen by calling function

  - by twiga

  Hi There, I have an interesting problem, which is a function that returns a Dictionary<String,HashSet<String>>. The function converts some primitive structs to a Dictionary Class. The function is called as follows: Dictionary<String, HashSet<String>> Myset = new Dictionary<String,HashSet<String>>(); Myset = CacheConverter.MakeDictionary(_myList); Upon execution of the two lines above, Myset is non-existent to the debugger. Adding a watch results in: "The name 'Myset' does not exist in the current context" public Dictionary<String, HashSet<String>> MakeDictionary(LightWeightFetchListCollection _FetchList) { Dictionary<String, HashSet<String>> _temp = new Dictionary<String, HashSet<String>>(); // populate the Dictionary // return return _temp; } The Dictionary _temp is correctly populated by the called function and _temp contains all the expected values. The problem seems to be with the dictionary not being returned at all. Examples I could find on the web of functions returning primitive Dictionary<string,string> work as expected.

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• Self-describing file format for gigapixel images?

  - by Adam Goode

  In medical imaging, there appears to be two ways of storing huge gigapixel images: Use lots of JPEG images (either packed into files or individually) and cook up some bizarre index format to describe what goes where. Tack on some metadata in some other format. Use TIFF's tile and multi-image support to cleanly store the images as a single file, and provide downsampled versions for zooming speed. Then abuse various TIFF tags to store metadata in non-standard ways. Also, store tiles with overlapping boundaries that must be individually translated later. In both cases, the reader must understand the format well enough to understand how to draw things and read the metadata. Is there a better way to store these images? Is TIFF (or BigTIFF) still the right format for this? Does XMP solve the problem of metadata? The main issues are: Storing images in a way that allows for rapid random access (tiling) Storing downsampled images for rapid zooming (pyramid) Handling cases where tiles are overlapping or sparse (scanners often work by moving a camera over a slide in 2D and capturing only where there is something to image) Storing important metadata, including associated images like a slide's label and thumbnail Support for lossy storage What kind of (hopefully non-proprietary) formats do people use to store large aerial photographs or maps? These images have similar properties.

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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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• Code bacteria: evolving mathematical behavior

  - by Stefano Borini

  It would not be my intention to put a link on my blog, but I don't have any other method to clarify what I really mean. The article is quite long, and it's in three parts (1,2,3), but if you are curious, it's worth the reading. A long time ago (5 years, at least) I programmed a python program which generated "mathematical bacteria". These bacteria are python objects with a simple opcode-based genetic code. You can feed them with a number and they return a number, according to the execution of their code. I generate their genetic codes at random, and apply an environmental selection to those objects producing a result similar to a predefined expected value. Then I let them duplicate, introduce mutations, and evolve them. The result is quite interesting, as their genetic code basically learns how to solve simple equations, even for values different for the training dataset. Now, this thing is just a toy. I had time to waste and I wanted to satisfy my curiosity. however, I assume that something, in terms of research, has been made... I am reinventing the wheel here, I hope. Are you aware of more serious attempts at creating in-silico bacteria like the one I programmed? Please note that this is not really "genetic algorithms". Genetic algorithms is when you use evolution/selection to improve a vector of parameters against a given scoring function. This is kind of different. I optimize the code, not the parameters, against a given scoring function.

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• How to Manage CSS Explosion

  - by Jason

  I have been heavily relying on CSS for a website that I am working on (currently, everything is done as property values within each tag on the website and I'm trying to get away from that to make updates significantly easier). The problem I am running into, is I'm starting to get a bit of "CSS explosion" going on. It is becoming difficult for me to decide how to best organize and abstract data within the CSS file. For example: I am using a large number of div tags within the website (previously it was completely tables based). So I'm starting to get a lot of CSS that looks like this... div.title { background-color: Blue; color: White; text-align: center; } div.footer { /* Stuff Here */ } div.body { /* Stuff Here */ } etc. It's not too bad yet, but since I am learning here, I was wondering if recommendations could be made on how best to organize the various parts of a CSS file. What I don't want to get to is where I have a separate CSS attribute for every single thing on my website (which I have seen happen), and I always want the CSS file to be fairly intuitive. (P.S. I do realize this is a very generic, high-level question. My ultimate goal is to make it easy to use the CSS files and demonstrate their power to increase the speed of web development so other individuals that may work on this site in the future will also get into the practice of using them rather than hard-coding values everywhere.)

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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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• need a near 100% uptime third-party web-accesible hosting for static web resources

  - by Jared Henderson

  I hope this makes sense: my business sells a website template, we currently have about 10,000 users. For various reasons that are unimportant to this question, I try to keep the file size of the zipped template we give them as small as possible. Because of this, I have taken a bunch of images and a couple of static files used by the template and moved them to external hosting. They are referenced by absolute URL in the css and markup, instead of shipping all of those images and files with every template. So, basically 10,000+ and growing users are requesting images and files from a third-party host. I don't use my own webhosting for this because I still kind of use a medium-cheap shared hosting for my website, and if it goes down, 10,000+ users are potentially effected. Currently I'm having the template directly access files inside of an open-source google-code project that I created for just this purpose. But, that seems like a bastardization of what a google-code repository is for, and plus, google code (i've found out) often spews 502 bad gateway errors for hours at a time. So, anyway, my question is: where is the right kind of place to host these? Obviously I'm willing to pay. My main needs are speed and uptime, since the images and files are being requested from thousands of different websites every day. Is this something that I should use Amazon S3 for? I'm guessing there's some kind of service exactly for this kind of need, but I'm at a loss to figure out what it is.

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• Java performance issue

  - by Colby77

  Hi, I've got a question related to java performance and method execution. In my app there are a lot of place where I have to validate some parameter, so I've written a Validator class and put all the validation methods into it. Here is an example: public class NumberValidator { public static short shortValidator(String s) throws ValidationException{ try{ short sh = Short.parseShort(s); if(sh < 1){ throw new ValidationException(); } return sh; }catch (Exception e) { throw new ValidationException("The parameter is wrong!"); } } ... But I'm thinking about that. Is this OK? It's OO and modularized, but - considering performance - is it a good idea? What if I had awful lot of invocation at the same time? The snippet above is short and fast, but there are some methods that take more time. What happens when there are a lot of calling to a static method or an instance method in the same class and the method is not synchronized? All the calling methods have to fall in line and the JVM executes them sequentially? Is it a good idea to have some class that are identical to the above-mentioned and randomly call their identical methods? I think it is not, because "Don't repeat yourself " and "Duplication is Evil" etc. But what about performance? Thanks is advance.

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• DBD::CSV: Problem with file-name-extensions

  - by sid_com

  In this script I have problems with file-name-extensions: if I use /home/mm/test_x it works, with file named /home/mm/test_x.csv it doesn't: #!/usr/bin/env perl use warnings; use strict; use 5.012; use DBI; my $table_1 = '/home/mm/test_1.csv'; my $table_2 = '/home/mm/test_2.csv'; #$table_1 = '/home/mm/test_1'; #$table_2 = '/home/mm/test_2'; my $dbh = DBI->connect( "DBI:CSV:" ); $dbh->{RaiseError} = 1; $table_1 = $dbh->quote_identifier( $table_1 ); $table_2 = $dbh->quote_identifier( $table_2 ); my $sth = $dbh->prepare( "SELECT a.id, a.name, b.city FROM $table_1 AS a NATURAL JOIN $table_2 AS b" ); $sth->execute; $sth->dump_results; $dbh->disconnect; Output with file-name-extention: DBD::CSV::st execute failed: Execution ERROR: No such column '"/home/mm/test_1.csv".id' called from /usr/local/lib/perl5/site_perl/5.12.0/x86_64-linux/DBD/File.pm at 570. Output without file-name-extension: '1', 'Brown', 'Laramie' '2', 'Smith', 'Watertown' 2 rows Is this a bug?

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• DataTable won't DataBind with a DataTable.NewRow()

  - by David

  Is DataRow.NewRow() insufficient as the only row in a DataTable? I would expect this to work, but it doesn't. It's near the end of my Page_Load inside my If(!Postback) block. gridCPCP is GridView DataTable dt = new DataTable(); dt.Columns.Add("ID", int.MinValue.GetType()); dt.Columns.Add("Code", string.Empty.GetType()); dt.Columns.Add("Date", DateTime.MinValue.GetType()); dt.Columns.Add("Date2", DateTime.MinValue.GetType()); dt.Columns.Add("Filename", string.Empty.GetType()); //code to add rows if (dt.Rows.Count > 0) { gridCPCP.DataSource = dt; gridCPCP.DataBind(); } else { dt.Rows.Add(dt.NewRow()); gridCPCP.DataSource = dt; gridCPCP.DataBind(); //EXCEPTION int TotalColumns = gridCPCP.Rows[0].Cells.Count; gridCPCP.Rows[0].Cells.Clear(); gridCPCP.Rows[0].Cells.Add(new TableCell()); gridCPCP.Rows[0].Cells[0].ColumnSpan = TotalColumns; gridCPCP.Rows[0].Cells[0].Text = "No Record Found"; } The exception throws on gridCPCP.DataBind() and only when execution reaches the else block. If there were rows added above via dt.Rows.Add(new object[] { ... } binding works. System.ArgumentOutOfRangeException: Length cannot be less than zero. Parameter name: length

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• BackgroundWorker might be causing my application to hang

  - by alexD

  I have a Form that uses a BackgroundWorker to execute a series of tests. I use the ProgressChanged event to send messages to the main thread, which then does all of the updates on the UI. I've combed through my code to make sure I'm not doing anything to the UI in the background worker. There are no while loops in my code and the BackgroundWorker has a finite execution time (measured in seconds or minutes). However, for some reason when I lock my computer, often times the application will be hung when I log back in. The thing is, the BackgroundWorker isn't even running when this happens. The reason I believe it is related to the BackgroundWorker though is because the form only hangs when the BackgroundWorker has been executed since the application was loaded (it only runs when given a certain user input). I pass this thread a List of TreeNodes from a TreeView in my UI through the RunWorkerAsync method, but I only read those nodes in the worker thread..any modifications I make to them is done in the UI thread through the progressChanged event. I do use Thread.Sleep in my worker thread to execute tests at timed intervals (which involves sending messages over a TCP socket, which was not created in the worker thread). I am completely perplexed as to why my application might be hanging. I'm sure I'm doing something 'illegal' somewhere, I just don't know what.

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• How to access C arrays from assembler for Windows x64?

  - by 0xdword32

  I've written an assembler function to speed up a few things for image processing (images are created with CreateDIBSection). For Win32 the assembler code works without problems, but for Win64 I get a crash as soon as I try to access my array data. I put the relevant info in a struct and my assembler function gets a pointer to this struct. The struct pointer is put into ebx/rbx and with indexing I read the data from the struct. Any idea what I am doing wrong? I use nasm together with Visual Studio 2008 and for Win64 I set "default rel". C++ code: struct myData { tUInt32 ulParam1; void* pData; }; CallMyAssemblerFunction(&myData); Assembler Code: Win32: ... push ebp; mov ebp,esp mov ebx, [ebp + 8]; pointer to our struct mov eax, [ebx]; ulParam1 mov esi, [ebx + 4]; pData, 4 byte pointer movd xmm0, [esi]; ... Win64: ... mov rbx, rcx; pointer to our struct mov eax, [rbx]; ulParam1 mov rsi, [rbx + 4]; pData, 8 byte pointer movd xmm0, [rsi]; CRASH! ...

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• How can I make this method more Scalalicious

  - by Neil Chambers

  I have a function that calculates the left and right node values for some collection of treeNodes given a simple node.id, node.parentId association. It's very simple and works well enough...but, well, I am wondering if there is a more idiomatic approach. Specifically is there a way to track the left/right values without using some externally tracked value but still keep the tasty recursion. /* * A tree node */ case class TreeNode(val id:String, val parentId: String){ var left: Int = 0 var right: Int = 0 } /* * a method to compute the left/right node values */ def walktree(node: TreeNode) = { /* * increment state for the inner function */ var c = 0 /* * A method to set the increment state */ def increment = { c+=1; c } // poo /* * the tasty inner method * treeNodes is a List[TreeNode] */ def walk(node: TreeNode): Unit = { node.left = increment /* * recurse on all direct descendants */ treeNodes filter( _.parentId == node.id) foreach (walk(_)) node.right = increment } walk(node) } walktree(someRootNode) Edit - The list of nodes is taken from a database. Pulling the nodes into a proper tree would take too much time. I am pulling a flat list into memory and all I have is an association via node id's as pertains to parents and children. Adding left/right node values allows me to get a snapshop of all children (and childrens children) with a single SQL query. The calculation needs to run very quickly in order to maintain data integrity should parent-child associations change (which they do very frequently). In addition to using the awesome Scala collections I've also boosted speed by using parallel processing for some pre/post filtering on the tree nodes. I wanted to find a more idiomatic way of tracking the left/right node values. After looking at the answers listed I have settled on this synthesised version: def walktree(node: TreeNode) = { def walk(node: TreeNode, counter: Int): Int = { node.left = counter node.right = treeNodes .filter( _.parentId == node.id) .foldLeft(counter+1) { (counter, curnode) => walk(curnode, counter) + 1 } node.right } walk(node,1) }

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• Error handling in PHP

  - by Industrial

  Hi guys, We're building a PHP app based on Good old MVC (codeigniter framework) and have run into trouble with a massive chained action that consists of multiple model calls, that together is a part of a big transaction to the database. We want to be able to do a list of actions and get a status report of each one back from the function, whatever the outcome is. Our first initial idea was to utilize the exceptions of PHP5, but since we want to also need status messages that doesnt break the execution of the script, this was our solution that we came up with. It goes a little something like this: $sku = $this->addSku( $name ); if ($sku === false) { $status[] = 'Something gone terrible wrong'; $this->db->trans_rollback(); return $status; } $image= $this->addImage( $filename); if ($image=== false) { $error[] = 'Image could not be uploaded, check filesize'; $this->db->trans_rollback(); return $status; } Our controller looks like this: $var = $this->products->addProductGroup($array); if (is_array($var)) { foreach ($var as $error) { echo $error . '<br />'; } } It appears to be a very fragile solution to do what we need, but it's neither scalable, neither effective when compared to pure PHP exceptions for instance. Is this really the way that this kind of stuff generally is handled in MVC based apps? Thanks!

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• Best intro to C++ static metaprogramming?

  - by jwfearn

  Static metaprogramming (aka "template metaprogramming") is a great C++ technique that allows the execution of programs at compile-time. A light bulb went off in my head as soon as I read this canonical metaprogramming example: #include <iostream> using namespace std; template< int n > struct factorial { enum { ret = factorial< n - 1 >::ret * n }; }; template<> struct factorial< 0 > { enum { ret = 1 }; }; int main() { cout << "7! = " << factorial< 7 >::ret << endl; // 5040 return 0; } If one wants to learn more about C++ static metaprogramming, what are the best sources (books, websites, on-line courseware, whatever)?

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• Total Order between !different! volatile variables?

  - by andreas

  Hi all, Consider the following Java code: volatile boolean v1 = false; volatile boolean v2 = false; //Thread A v1 = true; if (v2) System.out.println("v2 was true"); //Thread B v2 = true; if (v1) System.out.println("v1 was true"); If there was a globally visible total order for volatile accesses then at least one println would always be reached. Is that actually guaranteed by the Java Standard? Or is an execution like this possible: A: v1 = true; B: v2 = true; A: read v2 = false; B: read v1 = false; A: v2 = true becomes visible (after the if) B: v1 = true becomes visible (after the if) I could only find statements about accesses to the same volatile variable in the Standard (but I might be missing something). "A write to a volatile variable (§8.3.1.4) v synchronizes-with all subsequent reads of v by any thread (where subsequent is defined according to the synchronization order)." http://java.sun.com/docs/books/jls/third_edition/html/memory.html#17.4.4 Thanks!

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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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• Whats wrong with this piece of code?

  - by cambr

  vector<int>& mergesort(vector<int> &a) { if (a.size() == 1) return a; int middle = a.size() / 2; vector<int>::const_iterator first = a.begin(); vector<int>::const_iterator mid = a.begin() + (middle - 1); vector<int>::const_iterator last = a.end(); vector<int> ll(first, mid); vector<int> rr(mid, last); vector<int> l = mergesort(ll); vector<int> r = mergesort(rr); vector<int> result; result.reserve(a.size()); int dp = 0, lp = 0, rp = 0; while (dp < a.size()) { if (lp == l.size()) { result[dp] = (r[rp]); rp++; } else if (rp == r.size()) { result[dp] = (l[lp]); lp++; } else if (l[lp] < r[rp]) { result[dp] = (l[lp]); lp++; } else { result[dp] = (r[rp]); rp++; } dp++; } a = result; return a; } It compiles coorectly but while execution, I am getting: This application has requested the runtime to end it in an unusual way. This is a weird error. Is there something that is fundamentally wrong with the code?

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• Dependency between operations in scala actors

  - by paradigmatic

  I am trying to parallelise a code using scala actors. That is my first real code with actors, but I have some experience with Java Mulithreading and MPI in C. However I am completely lost. The workflow I want to realise is a circular pipeline and can be described as the following: Each worker actor has a reference to another one, thus forming a circle There is a coordinator actor which can trigger a computation by sending a StartWork() message When a worker receives a StartWork() message, it process some stuff locally and sends DoWork(...) message to its neighbour in the circle. The neighbours do some other stuff and sends in turn a DoWork(...) message to its own neighbour. This continues until the initial worker receives a DoWork() message. The coordinator can send a GetResult() message to the initial worker and wait for a reply. The point is that the coordinator should only receive a result when data is ready. How can a worker wait that the job returned to it before answering the GetResult() message ? To speed up computation, any worker can receive a StartWork() at any time. Here is my first try pseudo-implementation of the worker: class Worker( neighbor: Worker, numWorkers: Int ) { var ready = Foo() def act() { case StartWork() => { val someData = doStuff() neighbor ! DoWork( someData, numWorkers-1 ) } case DoWork( resultData, remaining ) => if( remaining == 0 ) { ready = resultData } else { val someOtherData = doOtherStuff( resultData ) neighbor ! DoWork( someOtherData, remaining-1 ) } case GetResult() => reply( ready ) } } On the coordinator side: worker ! StartWork() val result = worker !? GetResult() // should wait

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• ConcurrentLinkedQueue$Node remains in heap after remove()

  - by action8

  I have a multithreaded app writing and reading a ConcurrentLinkedQueue, which is conceptually used to back entries in a list/table. I originally used a ConcurrentHashMap for this, which worked well. A new requirement required tracking the order entries came in, so they could be removed in oldest first order, depending on some conditions. ConcurrentLinkedQueue appeared to be a good choice, and functionally it works well. A configurable amount of entries are held in memory, and when a new entry is offered when the limit is reached, the queue is searched in oldest-first order for one that can be removed. Certain entries are not to be removed by the system and wait for client interaction. What appears to be happening is I have an entry at the front of the queue that occurred, say 100K entries ago. The queue appears to have the limited number of configured entries (size() == 100), but when profiling, I found that there were ~100K ConcurrentLinkedQueue$Node objects in memory. This appears to be by design, just glancing at the source for ConcurrentLinkedQueue, a remove merely removes the reference to the object being stored but leaves the linked list in place for iteration. Finally my question: Is there a "better" lazy way to handle a collection of this nature? I love the speed of the ConcurrentLinkedQueue, I just cant afford the unbounded leak that appears to be possible in this case. If not, it seems like I'd have to create a second structure to track order and may have the same issues, plus a synchronization concern.

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• is mysql index useful on column 'state' when only doing bit-operations on the column?

  - by Geert-Jan

  I have a lot of domain entities (stored in mysql) which undergo lots of different operations. Each operation is executed from a different program. I need to keep (flow)-state for these entities which I implemented in as a long field 'flowstate' used as a bitset. to query mysql for entities which have undergone a certain operation I do something like: select * from entities where state >> 7 & 1 = 1 Indicating bit 7 (cooresponding to operation 7) has run. (<-- simplified) Anyway, I really didn't pay attention to the performance implications of this setup in the beginning, and I think I'm in a bit of trouble since queries as the above run pretty slow. What I'd like to know: Does an mysql index on 'flowstate' help at all? After all it's not a single value Mysql can quickly find using a binary sort or whatever. If it doesn't, are there any other things I could do to speed things up? . Are there special 'mask-indices' for fields with use-cases as the above? TIA, Geert-jan

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• Using the Apple Scripting bridge with Mail to send an attachment causes the message background to go

  - by Naym

  Hello, When I use the Apple Scripting Bridge to send a message with an attachment the background of the message is set to black which is a problem because the text is also black. The code in question is: MailApplication *mail = [SBApplication applicationWithBundleIdentifier:@"com.apple.Mail"]; /* create a new outgoing message object */ MailOutgoingMessage *emailMessage = [[[mail classForScriptingClass:@"outgoing message"] alloc] initWithProperties: [NSDictionary dictionaryWithObjectsAndKeys: emailSubject, @"subject", [self composeEmailBody], @"content", nil]]; /* add the object to the mail app */ [[mail outgoingMessages] addObject: emailMessage]; /* set the sender, show the message */ emailMessage.sender = [NSString stringWithFormat:@"%@ <%@>",[[[mail accounts] objectAtIndex:playerOptions.mailAccount] fullName],[[[[mail accounts] objectAtIndex:playerOptions.mailAccount] emailAddresses] objectAtIndex:0]]; emailMessage.visible = YES; /* create a new recipient and add it to the recipients list */ MailToRecipient *theRecipient = [[[mail classForScriptingClass:@"to recipient"] alloc] initWithProperties: [NSDictionary dictionaryWithObjectsAndKeys: opponentEmail, @"address", nil]]; [emailMessage.toRecipients addObject: theRecipient]; /* add an attachment, if one was specified */ if ( [playerInfo.gameFile length] > 0 ) { /* create an attachment object */ MailAttachment *theAttachment = [[[mail classForScriptingClass:@"attachment"] alloc] initWithProperties: [NSDictionary dictionaryWithObjectsAndKeys: playerInfo.gameFile, @"fileName", nil]]; /* add it to the list of attachments */ [[emailMessage.content attachments] addObject: theAttachment]; } /* send the message */ [emailMessage send]; The actual change to the background colour occurs on the second last line, which is: [[emailMessage.content attachments] addObject: theAttachment]; The code sections above are essentially lifted from the SBSendMail example code from Apple. At this stage I've really only made the changes necessary to integrate with the data from my application. If I build and run the SBSendMail example after freshly downloading it from Apple the message background is also changed to black with execution of the same line. It does not appear to matter which type of file is attached, where it is located, or on which computer or operating system is used. This could be a bug in Apple's scripting bridge but has anyone come across this problem and found a solution? ALternatively does anyone know if the background colour of a MailOutgoingMessage instance can be changed with the scripting bridge? Thanks for any assistance with this, Naym.

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• TypeError: Error #1009 - (Null reference error) With Flash.

  - by Wind Chimez

  I am not an expert in flash, but i do work with AS and tweak Flash projects , though not having deep expertise in it. Currently i need to revamp a flash website done by one another guy, and the code base given to me, upon execution is throwing the following error. "--- TypeError: Error #1009: Cannot access a property or method of a null object reference. at NewSite_fla::MainTimeline/__setProp_ContactOutP1_ContactOut_Contents_0() at NewSite_fla::MainTimeline/frame1() --" The structure of the project is like, it has the different sections split into different movie clips. There is no single main timeline, but click actions on different areas of seperate movie clips will take them between one another. All the AS logic of event handling are written inline in FLA , no seperate Document class exists. Preloader Movie clip is the first one getting loaded. As i understood the error is getting thrown initially itself, and it is not happening due to any Action script logic written inline, because it is throwing error even before hitting the first inline AS code. I am not able to figure Out what exactly it causing the problem, or where to resolve it. I really got stuck at this point. Any help will be great.I had not seen the particular solution i am looking for anywhere yet, though Error #1009 is common. I uploaded the fla, here ( http://tinyurl.com/249e95p ), for reference.It may not be working , since the included/refered video files and all are not there, but reviwing the action code/movie clips will be possible. Please let me know if somebody will be able to trace the issue exactly.

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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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