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What does the windbg command "kd" do?

- by Oskar

I ran kd by mistake and got some output that inteerested me, a reference to a line of code in my module that I can't see on the call stack of any thread. The lines weren't the beginnning of the method so I don't think the reference is to a function pointer, but possibly the result of an exception being stored in memory??? Of course, that happens to be what I'm looking for... Update: The stack trace of the exception is: 0:000> kb *** Stack trace for last set context - .thread/.cxr resets it ChildEBP RetAddr Args to Child 0174f168 734ea84f 2cb9e950 00000000 2cb9e950 kernel32!LoadTimeZoneInformation+0x2b 0174f1c4 734ead92 00000022 00000001 000685d0 msvbvm60! RUN_INSTMGR::ExecuteInitTerm+0x178 0174f1f8 734ea9ee 00000000 0000002f 2dbc2abc msvbvm60! RUN_INSTMGR::CreateObjInstanceWithParts+0x1e4 0174f278 7350414e 2cb9e96c 00000000 0174f2f0 msvbvm60! RUN_INSTMGR::CreateObjInstance+0x14d 0174f2e4 734fa071 00000000 2cb9e96c 0174f2fc msvbvm60!RcmConstructObjectInstance+0x75 0174f31c 00976ef1 2cb9e950 00591bc0 0174fddc msvbvm60!__vbaNew+0x21 and into our code (create a new Form derived class) the dds output: 0:000> dds esp-0x40 esp+0x100 0174f05c 00000000 0174f060 00000000 0174f064 00000000 0174f068 00000000 0174f06c 00000000 0174f070 00000000 0174f074 00000000 0174f078 00000000 0174f07c 00000000 0174f080 00000000 0174f084 00000000 0174f088 00000000 0174f08c 00000000 0174f090 00000000 0174f094 00000000 0174f098 00000000 0174f09c 007f4f9b ourDll!formDerivedClass::Form_Initialize+0x10b [C:\Buildbox\formDerivedClass.frm @ 1452] etc which seems to indicate that Initialize is being called even though it isn't on the stack trace of either this exception or any of the threads. As suggested, it might all be a mismatch between pdbs and dlls, but it seems a coincidence that we end up in the right classes and methods

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Silverlight performance with many loaded controls

- by gius

I have a SL application with many DataGrids (from Silverlight Toolkit), each on its own view. If several DataGrids are opened, changing between views (TabItems, for example) takes a long time (few seconds) and it freezes the whole application (UI thread). The more DataGrids are loaded, the longer the change takes. These DataGrids that slow the UI chanage might be on other places in the app and not even visible at that moment. But once they are opened (and loaded with data), they slow showing other DataGrids. Note that DataGrids are NOT disposed and then recreated again, they still remain in memory, only their parent control is being hidden and visible again. I have profiled the application. It shows that agcore.dll's SetValue function is the bottleneck. Unfortunately, debug symbols are not available for this Silverlight native library responsible for drawing. The problem is not in the DataGrid control - I tried to replace it with XCeed's grid and the performance when changing views is even worse. Do you have any idea how to solve this problem? Why more opened controls slow down other controls? I have created a sample that shows this issue: http://cenud.cz/PerfTest.zip UPDATE: Using VS11 profiler on the sample provided suggests that the problem could be in MeasureOverride being called many times (for each DataGridCell, I guess). But still, why is it slower as more controls are loaded elsewhere? Is there a way to improve the performance?

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How do I rewrite a for loop with a shared dependency using actors

- by Thomas Rynne

We have some code which needs to run faster. Its already profiled so we would like to make use of multiple threads. Usually I would setup an in memory queue, and have a number of threads taking jobs of the queue and calculating the results. For the shared data I would use a ConcurrentHashMap or similar. I don't really want to go down that route again. From what I have read using actors will result in cleaner code and if I use akka migrating to more than 1 jvm should be easier. Is that true? However, I don't know how to think in actors so I am not sure where to start. To give a better idea of the problem here is some sample code: case class Trade(price:Double, volume:Int, stock:String) { def value(priceCalculator:PriceCalculator) = (priceCalculator.priceFor(stock)-> price)*volume } class PriceCalculator { def priceFor(stock:String) = { Thread.sleep(20)//a slow operation which can be cached 50.0 } } object ValueTrades { def valueAll(trades:List[Trade], priceCalculator:PriceCalculator):List[(Trade,Double)] = { trades.map { trade => (trade,trade.value(priceCalculator)) } } def main(args:Array[String]) { val trades = List( Trade(30.5, 10, "Foo"), Trade(30.5, 20, "Foo") //usually much longer ) val priceCalculator = new PriceCalculator val values = valueAll(trades, priceCalculator) } } I'd appreciate it if someone with experience using actors could suggest how this would map on to actors.

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Old dll.config problem !

- by user313421

Since 2005 as I googled it's a problem for who needs to read the configuration of an assembly from it's config file "*.dll.config" and Microsoft didn't do anything yet. Story: If you try to read a setting from a class library (plug-in) you fail. Instead the main application domain (EXE which is using the plug-in) config is read and because probably there's not such a config your plug-in will use default setting which is hard-coded when you create it's settings for first time. Any change to .dll.config wouldn't see by your plug-in and you wonder why it's there! If you want to replace it and start searching you may find something like this: http://stackoverflow.com/questions/594298/c-dll-config-file But just some ideas and one line code. A good replacement for built-in config shouldn't read from file system each time we need a config value, so we can store them in memory; Then what if user changes config file ? we need a FileSystemWatcher and we need some design like singleton ... and finally we are at the same point configuration of .NET is except our one's working. It seems MS did everything but forgot why they built the ".dll.config". Since no DLL is gonna execute by itself, they are referenced from other apps (even if used in web) and so why there's such a "*.dll.config" file ? I'm not gonna argue if it's good to have multiple config files or not. It's my design (plug-able components). Finally { After these years, is there any good practice such as a custom setting class to add in each assemly and read from it's own config file ? }

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Constructor and Destructors in C++ [Not a question] [closed]

- by Jack

I am using gcc. Please tell me if I am wrong - Lets say I have two classes A & B class A { public: A(){cout<<"A constructor"<<endl;} ~A(){cout<<"A destructor"<<endl;} }; class B:public A { public: B(){cout<<"B constructor"<<endl;} ~B(){cout<<"B destructor"<<endl;} }; 1) The first line in B's constructor should be a call to A's constructor ( I assume compiler automatically inserts it). Also the last line in B's destructor will be a call to A's destructor (compiler does it again). Why was it built this way? 2) When I say A * a = new B(); compiler creates a new B object and checks to see if A is a base class of B and if it is it allows 'a' to point to the newly created object. I guess that is why we don't need any virtual constructors. ( with help from @Tyler McHenry , @Konrad Rudolph) 3) When I write delete a compiler sees that a is an object of type A so it calls A's destructor leading to a problem which is solved by making A's destructor virtual. As user - Little Bobby Tables pointed out to me all destructors have the same name destroy() in memory so we can implement virtual destructors and now the call is made to B's destructor and all is well in C++ land. Please comment.

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Avoiding a fork()/SIGCHLD race condition

- by larry

Please consider the following fork()/SIGCHLD pseudo-code. // main program excerpt for (;;) { if ( is_time_to_make_babies ) { pid = fork(); if (pid == -1) { /* fail */ } else if (pid == 0) { /* child stuff */ print "child started" exit } else { /* parent stuff */ print "parent forked new child ", pid children.add(pid); } } } // SIGCHLD handler sigchld_handler(signo) { while ( (pid = wait(status, WNOHANG)) > 0 ) { print "parent caught SIGCHLD from ", pid children.remove(pid); } } In the above example there's a race-condition. It's possible for "/* child stuff */" to finish before "/* parent stuff */" starts which can result in a child's pid being added to the list of children after it's exited, and never being removed. When the time comes for the app to close down, the parent will wait endlessly for the already-finished child to finish. One solution I can think of to counter this is to have two lists: started_children and finished_children. I'd add to started_children in the same place I'm adding to children now. But in the signal handler, instead of removing from children I'd add to finished_children. When the app closes down, the parent can simply wait until the difference between started_children and finished_children is zero. Another possible solution I can think of is using shared-memory, e.g. share the parent's list of children and let the children .add and .remove themselves? But I don't know too much about this. EDIT: Another possible solution, which was the first thing that came to mind, is to simply add a sleep(1) at the start of /* child stuff */ but that smells funny to me, which is why I left it out. I'm also not even sure it's a 100% fix. So, how would you correct this race-condition? And if there's a well-established recommended pattern for this, please let me know! Thanks.

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How to get encoding from MAPI message with PR_BODY_A tag (windows mobile)?

- by SadSido

Hi, everyone! I am developing a program, that handles incoming e-mail and sms through windows-mobile MAPI. The code basically looks like that: ulBodyProp = PR_BODY_A; hr = piMessage->OpenProperty(ulBodyProp, NULL, STGM_READ, 0, (LPUNKNOWN*)&piStream); if (hr == S_OK) { // ... get body size in bytes ... STATSTG statstg; piStream->Stat(&statstg, 0); ULONG cbBody = statstg.cbSize.LowPart; // ... allocate memory for the buffer ... BYTE* pszBodyInBytes = NULL; boost::scoped_array<BYTE> szBodyInBytesPtr(pszBodyInBytes = new BYTE[cbBody+2]); // ... read body into the pszBodyInBytes ... } That works and I have a message body. The problem is that this body is multibyte encoded and I need to return a Unicode string. I guess, I have to use ::MultiByteToWideChar() function, but how can I guess, what codepage should I apply? Using CP_UTF8 is naive, because it can simply be not in UTF8. Using CP_ACP works, well, sometimes, but sometimes does not. So, my question is: how can I retrieve the information about message codepage. Does MAPI provide any functions for it? Or is there a way to decode multibyte string, other than MultiByteToWideChar()? Thanks!

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How to optimize Conway's game of life for CUDA?

- by nlight

I've written this CUDA kernel for Conway's game of life: global void gameOfLife(float* returnBuffer, int width, int height) { unsigned int x = blockIdx.x*blockDim.x + threadIdx.x; unsigned int y = blockIdx.y*blockDim.y + threadIdx.y; float p = tex2D(inputTex, x, y); float neighbors = 0; neighbors += tex2D(inputTex, x+1, y); neighbors += tex2D(inputTex, x-1, y); neighbors += tex2D(inputTex, x, y+1); neighbors += tex2D(inputTex, x, y-1); neighbors += tex2D(inputTex, x+1, y+1); neighbors += tex2D(inputTex, x-1, y-1); neighbors += tex2D(inputTex, x-1, y+1); neighbors += tex2D(inputTex, x+1, y-1); __syncthreads(); float final = 0; if(neighbors < 2) final = 0; else if(neighbors 3) final = 0; else if(p != 0) final = 1; else if(neighbors == 3) final = 1; __syncthreads(); returnBuffer[x + y*width] = final; } I am looking for errors/optimizations. Parallel programming is quite new to me and I am not sure if I get how to do it right. The rest of the app is: Memcpy input array to a 2d texture inputTex stored in a CUDA array. Output is memcpy-ed from global memory to host and then dealt with. As you can see a thread deals with a single pixel. I am unsure if that is the fastest way as some sources suggest doing a row or more per thread. If I understand correctly NVidia themselves say that the more threads, the better. I would love advice on this on someone with practical experience.

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Implementing list position locator in C++?

- by jfrazier

I am writing a basic Graph API in C++ (I know libraries already exist, but I am doing it for the practice/experience). The structure is basically that of an adjacency list representation. So there are Vertex objects and Edge objects, and the Graph class contains: list<Vertex *> vertexList list<Edge *> edgeList Each Edge object has two Vertex* members representing its endpoints, and each Vertex object has a list of Edge* members representing the edges incident to the Vertex. All this is quite standard, but here is my problem. I want to be able to implement deletion of Edges and Vertices in constant time, so for example each Vertex object should have a Locator member that points to the position of its Vertex* in the vertexList. The way I first implemented this was by saving a list::iterator, as follows: vertexList.push_back(v); v->locator = --vertexList.end(); Then if I need to delete this vertex later, then rather than searching the whole vertexList for its pointer, I can call: vertexList.erase(v->locator); This works fine at first, but it seems that if enough changes (deletions) are made to the list, the iterators will become out-of-date and I get all sorts of iterator errors at runtime. This seems strange for a linked list, because it doesn't seem like you should ever need to re-allocate the remaining members of the list after deletions, but maybe the STL does this to optimize by keeping memory somewhat contiguous? In any case, I would appreciate it if anyone has any insight as to why this happens. Is there a standard way in C++ to implement a locator that will keep track of an element's position in a list without becoming obsolete? Much thanks, Jeff

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Python: Access dictionary value inside of tuple and sort quickly by dict value

- by Aquat33nfan

I know that wasn't clear. Here's what I'm doing specifically. I have my list of dictionaries here: dict = [{int=0, value=A}, {int=1, value=B}, ... n] and I want to take them in combinations, so I used itertools and it gave me a tuple (Well, okay it gave me a memory object that I then used enumerate on so I could loop over it and enumerate gave ma tuple): for (index, tuple) in enumerate(combinations(dict, 2)): and this is where I have my problem. I want to identify which of the two items in the combination has the bigger 'int' value and which has the smaller value and assign them to variables (I'm actually using more than 2 in the combination so I can't just say if tuple[0]['int'] tuple[1]['int'] and do the assignment because I'd have to list this out a bunch of times and that's hard to manage). I was going to assign each 'int' value to a variable, sort it in a list, index the 'int' value in the list by 1, 2, 3, 4, 5 ... etc., then go back and access the dictionary I wanted by the int value and then assign the dictionary to a variable so I knew which was bigger. But I have a big list and lists and variable assignments are resource intensive and this is taking a long time (I had only a little bit of that written and it was taking forever to run). So I was hoping someone knew a fast way to do this. I actually could list out every possible combination of assignmnets using the if/thens but it's just like 5 pages of if/thens and assignments and is hard to read and manage when I want to change it. You've probably gathered this, but I"m new at programming. thx

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Silverlight Socket Constantly Returns With Empty Buffer

- by Benny

I am using Silverlight to interact with a proxy application that I have developed but, without the proxy sending a message to the Silverlight application, it executes the receive completed handler with an empty buffer ('\0's). Is there something I'm doing wrong? It is causing a major memory leak. this._rawBuffer = new Byte[this.BUFFER_SIZE]; SocketAsyncEventArgs receiveArgs = new SocketAsyncEventArgs(); receiveArgs.SetBuffer(_rawBuffer, 0, _rawBuffer.Length); receiveArgs.Completed += new EventHandler<SocketAsyncEventArgs>(ReceiveComplete); this._client.ReceiveAsync(receiveArgs); if (args.SocketError == SocketError.Success && args.LastOperation == SocketAsyncOperation.Receive) { // Read the current bytes from the stream buffer int bytesRecieved = this._client.ReceiveBufferSize; // If there are bytes to process else the connection is lost if (bytesRecieved > 0) { try { //Find out what we just received string messagePart = UTF8Encoding.UTF8.GetString(_rawBuffer, 0, _rawBuffer.GetLength(0)); //Take out any trailing empty characters from the message messagePart = messagePart.Replace('\0'.ToString(), ""); //Concatenate our current message with any leftovers from previous receipts string fullMessage = _theRest + messagePart; int seperator; //While the index of the seperator (LINE_END defined & initiated as private member) while ((seperator = fullMessage.IndexOf((char)Messages.MessageSeperator.Terminator)) > 0) { //Pull out the first message available (up to the seperator index string message = fullMessage.Substring(0, seperator); //Queue up our new message _messageQueue.Enqueue(message); //Take out our line end character fullMessage = fullMessage.Remove(0, seperator + 1); } //Save whatever was NOT a full message to the private variable used to store the rest _theRest = fullMessage; //Empty the queue of messages if there are any while (this._messageQueue.Count > 0) { ... } } catch (Exception e) { throw e; } // Wait for a new message if (this._isClosing != true) Receive(); } } Thanks in advance.

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NSCollectionView: Can the same object not be in the array more than once or is this a bug?

- by Sean

I may be doing this all wrong, but I thought I was on the right track until I hit this little snag. Basically I was putting together a toy using NSCollectionView and trying to understand how to hook that all up using IB. I have a button which will add a couple of strings to the NSArrayController: The first time I press this button, my strings appear in the collection view as expected: The second time I press the button, the views scroll down and room is made - but the items don't appear to get added. I just see blank space: The button is implemented as follows (controller is a pointer to the NSArrayController I added in IB): - (IBAction)addStuff:(id)control { [controller addObjects:[NSArray arrayWithObjects:@"String 1",@"String 2",@"String 3",nil]]; } I'm not sure what I'm doing wrong. Rather than try to explain all the connections/binds/etc, if you need more info, I'd be grateful if you could just take a quick look at the toy project itself. UPDATE: After more experimentation as suggested by James Williams, it seems the problem stems from having multiple objects with the same memory address in the array. This confuses either NSArrayController or NSCollectionView (not sure which). Changing my addStuff: to this resulted in the behavior I originally expected: [controller addObjects:[NSArray arrayWithObjects:[NSMutableString stringWithString:@"String 1"],[NSMutableString stringWithString:@"String 2"],[NSMutableString stringWithString:@"String 3"],nil]]; So the question now, I guess, is if this is a bug I should report to Apple or if this is intended/documented behavior and I just missed it?

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How to code a 'Next in Results' within search results in PHP

- by thebluefox

Right, bit of a head scratcher, although I've got a feeling there's an obvious answer and I'm just not seeing the wood for the trees. Baiscally, using Solr as a search engine for my site, bringing back 15 results per page. When you click on a result, you get a detail page, that has a "Next in Results" link on it, which obviously forwards you on to the next result. Whats the best way of doing this? I've come up with a few solutions but they're either too inpractical or just don't work. I could store all the ids in a session array, then grab the one after the current one and put that in the link. But with possibly hundreds/thousands of results, the memory that array would need, and the performance hit of dealing with it isn't practical. I could take the same approach and put it into the db, but I'll still have to deal with a potentially huge array when I grab them out of the db. Or; I could do the search again, only returning the id's, and grab the one after the one we're currently looking at. I think this could be the best option? Although it does seem kind of messy, namely because of when I have to select the id thats on a different 'page' (ie the 16th, 31st etc result). Unless I pass through where it was in the results, and select from there, but that still doesn't seem like the right way to do it. I'm really sorry if this is just complete nonsense, any help is massively appreciated as always, Cheers guys!

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Weak hashmap with weak references to the values?

- by Razor Storm

I am building an android app where each entity has a bitmap that represents its sprite. However, each entity can be be duplicated (there might be 3 copies of entity asdf for example). One approach is to load all the sprites upfront, and then put the correct sprite in the constructors of the entities. However, I want to decode the bitmaps lazily, so that the constructors of the entities will decode the bitmaps. The only problem with this is that duplicated entities will load the same bitmap twice, using 2x the memory (Or n times if the entity is created n times). To fix this, I built a SingularBitmapFactory that will store a decoded Bitmap into a hash, and if the same bitmap is asked for again, will simply return the previously hashed one instead of building a new one. Problem with this, though, is that the factory holds a copy of all bitmaps, and so won't ever get garbage collected. What's the best way to switch the hashmap to one with weakly referenced values? In otherwords, I want a structure where the values won't be GC'd if any other object holds a reference to it, but as long as no other objects refers it, then it can be GC'd.

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Using JRE 1.5, still maven says annotation not supported in -source 1.3

- by Abhijeet

Hi, I am using JRE 1.5. Still when I try to compile my code it fails by saying to use JRE 1.5 instead of 1.3 C:\temp\SpringExamplemvn -e clean install + Error stacktraces are turned on. [INFO] Scanning for projects... [INFO] ------------------------------------------------------------------------ [INFO] Building SpringExample [INFO] task-segment: [clean, install] [INFO] ------------------------------------------------------------------------ [INFO] [clean:clean {execution: default-clean}] [INFO] Deleting directory C:\temp\SpringExample\target [INFO] [resources:resources {execution: default-resources}] [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 6 resources [INFO] [compiler:compile {execution: default-compile}] [INFO] Compiling 6 source files to C:\temp\SpringExample\target\classes [INFO] ------------------------------------------------------------------------ [ERROR] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override [INFO] ------------------------------------------------------------------------ [INFO] Trace org.apache.maven.BuildFailureException: Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:715) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:556) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:535) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138) at org.apache.maven.cli.MavenCli.main(MavenCli.java:362) at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315) at org.codehaus.classworlds.Launcher.launch(Launcher.java:255) at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430) at org.codehaus.classworlds.Launcher.main(Launcher.java:375) Caused by: org.apache.maven.plugin.CompilationFailureException: Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:516) at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:114) at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694) ... 17 more [INFO] ------------------------------------------------------------------------ [INFO] Total time: 2 seconds [INFO] Finished at: Wed Dec 22 10:04:53 IST 2010 [INFO] Final Memory: 9M/16M [INFO] ------------------------------------------------------------------------ C:\temp\SpringExamplejavac -version javac 1.5.0_08 javac: no source files

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Framework or design pattern for mailing all users of a webapp

- by Todd Owen

My app takes care of user registration (with the option to receive email announcements), and can easily handle the actual template-based rendering of email for a given user. JavaMail provides the mail transport layer. But how should I design the application layer between the business objects (e.g. User) and the mail transport? The straightforward approach would be a simple, synchronous loop: iterate through the users, queue the emails, and be done with it. "Queue" might mean sending them straight to the MTA (mail server), or to an in-memory queue to be consumed by another thread. However, I also plan to implement features like throttling the rate of emails, processing bounced emails (NDRs), and maintaining status across application restarts. My intuition is that a good design would decouple this from both the business layer and the mail transport layer as much as possible. I wondered if others had solved this problem before, but after much searching I haven't found any Java libraries which seem to fit this problem. Standalone mail apps such as James or list servers are too large in scope; packages like Spring's MailSender or Commons Email are too small in scope (being basically drop-in replacements for JavaMail). For other languages I haven't found anything appropriate either. I'm curious about how other developers have gone about adding bulk mailing to their applications.

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Generated HTML word document not displaying image correctly

- by spiderdijon

I'm trying to add an image to a generated html word document that is embedded in a classic ASP page. The code looks something like this: <% Response.ContentType = "application/msword" %> <html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word"> ... <v:shape id="_x0000_s1030" type="#_x0000_t75" style='position:absolute; left:0;text-align:left;margin-left:0;margin-top:17.95pt;width:7in;height:116.85pt; z-index:2;mso-position-horizontal:center;mso-position-horizontal-relative:page; mso-position-vertical-relative:page'> <v:imagedata src="http://xxx/image001.gif" o:title="image001"/> <w:wrap anchorx="page" anchory="page"/> <w:anchorlock/> </v:shape><![endif]--><![if !vml]><span style='mso-ignore:vglayout;position: absolute;z-index:0;left:0px;margin-left:0px;margin-top:24px;width:672px; height:156px'><img width=672 height=156 src="http://xxx/image001.gif" v:shapes="_x0000_s1030"></span><![endif]> The image URL is correct and can be viewed through a browser, however when the word document opens, the image has a red x, with the error message: The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may be corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. If i copy the html code and try to open the word document on my local machine, it displays the image correctly. It just doesn't work when retrieving the document from the server. This happens for any images I try to add. Is there another way to add images to html-generated word documents that can be output from an asp page? Thanks.

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mmap only needed pages of kernel buffer to user space

- by axeoth

See also this answer: http://stackoverflow.com/a/10770582/1284631 I need something similar, but without having to allocate a buffer: the buffer is large, in theory, but the user space program only needs to access some parts of it (it mocks some registers of a hardware). As I cannot allocate with vmalloc_user() such a large buffer (kernel 32 bit, in embedded environment, no swap...), I followed the same approach as in the quoted answer, trying to allocate only those pages that are really requested by the user space. So: I use a my_mmap() function for the device file (actually, is the .mmap field of a struct uio_info) to set up the fields of the vma, then, in the vm_area_struct's .fault field (also named my_fault()), I should return a page. except that: In the my_fault() method of vm_area_struct, I cannot obtain a page through: vmf->page=vmalloc_to_page(my_buf + (vmf->pgoff << PAGE_SHIFT)); since there is no allocated buffer: my_buf = vmalloc_user(MY_BUF_SIZE); fails with "allocation failed: out of vmalloc space - use vmalloc= to increase size." (and there is no room or swap to increase that vmalloc= parameter). So, I would need to get a page from the kernel and fill the vmf->page field. How to allocate a page (I assume that the offset of the page is known, as it is vm->pgoff). What base memory should I use instead of my_buf? PS: I also did set up the vma->flags |= VM_NORESERVE; (in the my_mmap()), but not sure if it helps. Is there any vmalloc_user_unreserved()-like function? (let's say, lazy allocation) Also, writing 1 to /proc/sys/vm/overcommit_memory and large values (eg 500) to /proc/sys/vm/overcommit_ratio before trying to my_buf=vmalloc_user(<large_size>) didn't work.

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invasive vs non-invasive ref-counted pointers in C++

- by anon

For the past few years, I've generally accepted that if I am going to use ref-counted smart pointers invasive smart pointers is the way to go -- However, I'm starting to like non-invasive smart pointers due to the following: I only use smart pointers (so no Foo* lying around, only Ptr) I'm starting to build custom allocators for each class. (So Foo would overload operator new). Now, if Foo has a list of all Ptr (as it easily can with non-invasive smart pointers). Then, I can avoid memory fragmentation issues since class Foo move the objects around (and just update the corresponding Ptr). The only reason why this Foo moving objects around in non-invasive smart pointers being easier than invasive smart pointers is: In non-invasive smart pointers, there is only one pointer that points to each Foo. In invasive smart pointers, I have no idea how many objects point to each Foo. Now, the only cost of non-invasive smart pointers ... is the double indirection. [Perhaps this screws up the caches]. Does anyone have a good study of expensive this extra layer of indirection is?

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Getting wierd issue with TO_NUMBER function in Oracle

- by Fazal

I have been getting an intermittent issue when executing to_number function in the where clause on a varchar2 column if number of records exceed a certain number n. I used n as there is no exact number of records on which it happens. On one DB it happens after n was 1 million on another when it was 0.1. million. E.g. I have a table with 10 million records say Table Country which has field1 varchar2 containing numberic data and Id If I do a query as an example select * from country where to_number(field1) = 23 and id 1 and id < 100000 This works But if i do the query select * from country where to_number(field1) = 23 and id 1 and id < 100001 It fails saying invalid number Next I try the query select * from country where to_number(field1) = 23 and id 2 and id < 100001 It works again As I only got invalid number it was confusing, but in the log file it said Memory Notification: Library Cache Object loaded into SGA Heap size 3823K exceeds notification threshold (2048K) KGL object name :with sqlplan as ( select c006 object_owner, c007 object_type,c008 object_name from htmldb_collections where COLLECTION_NAME='HTMLDB_QUERY_PLAN' and c007 in ('TABLE','INDEX','MATERIALIZED VIEW','INDEX (UNIQUE)')), ws_schemas as( select schema from wwv_flow_company_schemas where security_group_id = :flow_security_group_id), t as( select s.object_owner table_owner,s.object_name table_name, d.OBJECT_ID from sqlplan s,sys.dba_objects d It seems its related to SGA size, but google did not give me much help on this. Does anyone have any idea about this issue with TO_NUMBER or oracle functions for large data?

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Rewriting a for loop in pure NumPy to decrease execution time

- by Statto

I recently asked about trying to optimise a Python loop for a scientific application, and received an excellent, smart way of recoding it within NumPy which reduced execution time by a factor of around 100 for me! However, calculation of the B value is actually nested within a few other loops, because it is evaluated at a regular grid of positions. Is there a similarly smart NumPy rewrite to shave time off this procedure? I suspect the performance gain for this part would be less marked, and the disadvantages would presumably be that it would not be possible to report back to the user on the progress of the calculation, that the results could not be written to the output file until the end of the calculation, and possibly that doing this in one enormous step would have memory implications? Is it possible to circumvent any of these? import numpy as np import time def reshape_vector(v): b = np.empty((3,1)) for i in range(3): b[i][0] = v[i] return b def unit_vectors(r): return r / np.sqrt((r*r).sum(0)) def calculate_dipole(mu, r_i, mom_i): relative = mu - r_i r_unit = unit_vectors(relative) A = 1e-7 num = A*(3*np.sum(mom_i*r_unit, 0)*r_unit - mom_i) den = np.sqrt(np.sum(relative*relative, 0))**3 B = np.sum(num/den, 1) return B N = 20000 # number of dipoles r_i = np.random.random((3,N)) # positions of dipoles mom_i = np.random.random((3,N)) # moments of dipoles a = np.random.random((3,3)) # three basis vectors for this crystal n = [10,10,10] # points at which to evaluate sum gamma_mu = 135.5 # a constant t_start = time.clock() for i in range(n[0]): r_frac_x = np.float(i)/np.float(n[0]) r_test_x = r_frac_x * a[0] for j in range(n[1]): r_frac_y = np.float(j)/np.float(n[1]) r_test_y = r_frac_y * a[1] for k in range(n[2]): r_frac_z = np.float(k)/np.float(n[2]) r_test = r_test_x +r_test_y + r_frac_z * a[2] r_test_fast = reshape_vector(r_test) B = calculate_dipole(r_test_fast, r_i, mom_i) omega = gamma_mu*np.sqrt(np.dot(B,B)) # write r_test, B and omega to a file frac_done = np.float(i+1)/(n[0]+1) t_elapsed = (time.clock()-t_start) t_remain = (1-frac_done)*t_elapsed/frac_done print frac_done*100,'% done in',t_elapsed/60.,'minutes...approximately',t_remain/60.,'minutes remaining'

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function returns after an XMLHttpRequest

- by ashays

Alright, I know questions like this have probably been asked dozens of times, but I can't seem to find a working solution for my project. Recently, while using jQuery for a lot of AJAX calls, I've found myself in a form of callback hell. Whether or not jQuery is too powerful for this project is beyond the scope of this question. So basically here's some code that shows what's going on: function check_form(table) { var file = "/models/"+table+".json"; var errs = {}; var xhr = $.getJSON(file, function(json) { for (key in json) { var k = key; var r = json[k]; $.extend(errs, check_item("#"+k,r)); } }); return errs; } And... as you can probably guess, I get an empty object returned. My original idea was to use some sort of onReadyStateChange idea that would return whenever the readyState had finally hit 4. This causes my application to hang indefinitely, though. I need these errors to decide whether or not the form is allowed to submit or not (as well as to tell the user where the errors are in the application. Any ideas? Edit. It's not the prettiest solution, but I've managed to get it to work. Basically, check_form has the json passed to it from another function, instead of loading it. I was already loading it there, too, so it's probably best that I don't continue to load the same file over and over again anyways. I was just worried about overloading memory. These files aren't absolutely huge, though, so I guess it's probably okay.

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How to format the node_redis info function output?

- by hh54188

I want check the Redis info on my pc with node, so I use node_redis and run the info function: var redis = require("redis"), client = redis.createClient(); client.on("connect", function () { client.info(function (err, replay) { console.log(replay); }) }) but the response is un-format: `#Server\r\nredis_version:2.6.16\r\nredis_git_sha1:00000000\r\nredis_git_dirty:0\r\nredis_mode:standalone\r\nos:Linux 3.8.0-29-generic x86_64\r\narch_bits:64\r\nmultiplexing_api:epoll\r\ngcc_version:4.6.3\r\nprocess_id:2941\r\nrun_id:e60f261a6f4f6f081563a47961315eff6b1c005d\r\ntcp_port:6379\r\nuptime_in_seconds:1777\r\nuptime_in_days:0\r\nhz:10\r\nlru_clock:2040689\r\n\r\n# Clients\r\nconnected_clients:2\r\nclient_longest_output_list:0\r\nclient_biggest_input_buf:0\r\nblocked_clients:0\r\n\r\n# Memory\r\nused_memory:562584\r\nused_memory_human:549.40K\r\nused_memory_rss:2031616\r\nused_memory_peak:561784\r\nused_memory_peak_human:548.62K\r\nused_memory_lua:31744\r\nmem_fragmentation_ratio:3.61\r\nmem_allocator:jemalloc-3.2.0\r\n\r\n# Persistence\r\nloading:0\r\nrdb_changes_since_last_save:0\r\nrdb_bgsave_in_progress:0\r\nrdb_last_save_time:1383553917\r\nrdb_last_bgsave_status:ok\r\nrdb_last_bgsave_time_sec:-1\r\nrdb_current_bgsave_time_sec:-1\r\naof_enabled:0\r\naof_rewrite_in_progress:0\r\naof_rewrite_scheduled:0\r\naof_last_rewrite_time_sec:-1\r\naof_current_rewrite_time_sec:-1\r\naof_last_bgrewrite_status:ok\r\n\r\n# Stats\r\ntotal_connections_received:3\r\ntotal_commands_processed:5\r\ninstantaneous_ops_per_sec:0\r\nrejected_connections:0\r\nexpired_keys:0\r\nevicted_keys:0\r\nkeyspace_hits:0\r\nkeyspace_misses:0\r\npubsub_channels:0\r\npubsub_patterns:0\r\nlatest_fork_usec:0\r\n\r\n# Replication\r\nrole:master\r\nconnected_slaves:0\r\n\r\n# CPU\r\nused_cpu_sys:0.13\r\nused_cpu_user:0.19\r\nused_cpu_sys_children:0.00\r\nused_cpu_user_children:0.00\r\n\r\n# Keyspace\r\n' How can I turn it to an object? like: { redis_version:2.6.16, redis_git_sha1:00000000, redis_git_dirty:0, ...... } so that I can read each property's value, get information I need

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Pump Messages During Long Operations + C# (it is urgent)

- by Newbie

Hi I have a web service that is doing huge computation and is taking more than a minute. I have generated the proxy file of the web service and then from my client end I am using the dll(of course I generated the proxy dll). My client side code is TimeSeries3D t = new TimeSeries3D(); int portfolioId = 4387919; string[] str = new string[2]; str[0] = "MKT_CAP"; DateRange dr = new DateRange(); dr.mStartDate = DateTime.Today; dr.mEndDate = DateTime.Today; Service1 sc = new Service1(); t = sc.GetAttributesForPortfolio(portfolioId, true, str, dr); But since it is taking to much time for the server to compute, after 1 minute I am receiving an error message The CLR has been unable to transition from COM context 0x33caf30 to COM context 0x33cb0a0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. Kindly guide me what to do? It is very urgent. Thanks

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How many users are sufficient to make a heavy load for web application

- by galymzhan

I have a web application, which has been suffering high load recent days. The application runs on single server which has 8-core Intel CPU and 4gb of RAM. Software: Drupal 5 (Apache 2, PHP5, MySQL5) running on Debian. After reaching 500 authenticated and 200 anonymous users (simultaneous), the application drastically decreases its performance up to total failure. The biggest load comes from authenticated users, who perform activities, causing insert/update/deletes on db. I think mysql is a bottleneck. Is it normal to slow down on such number of users? EDIT: I forgot to mention that I did some kind of profiling. I runned commands top, htop and they showed me that all memory was being used by MySQL! After some time MySQL starts to perform terribly slow, site goes down, and we have to restart/stop apache to reduce load. Administrators said that there was about 200 active mysql connections at that moment. The worst point is that we need to solve this ASAP, I can't do deep profiling analysis/code refactoring, so I'm considering 2 ways: my tables are MyIsam, I heard they use table-level locking which is very slow, is it right? could I change it to Innodb without worry? what if I take MySQL, and move it to dedicated machine with a lot of RAM?

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