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  • What would be the best .NET 2.0 type to represent .NET 3.5 HashSet<T>?

    - by Will Marcouiller
    I'm writing myself a class library to manage Active Directory. I have an interface: Public Interface ISourceAnnuaire(Of T as {IGroupe, ITop, IUniteOrganisation, IUtilisateur}) Readonly Property Changements As Dictionary(Of T, HashSet(Of String)) End Interface This Changements property is used to save in memory the changes that occur on a particular element that is part of the source. However, I am stuck with .NET Framework 2.0. What would be the closest .NET 2.0 for HashSet(Of String)?

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  • Performance tuning of a Hibernate+Spring+MySQL project operation that stores images uploaded by user

    - by Umar
    Hi I am working on a web project that is Spring+Hibernate+MySQL based. I am stuck at a point where I have to store images uploaded by a user into the database. Although I have written some code that works well for now, but I believe that things will mess up when the project would go live. Here's my domain class that carries the image bytes: @Entity public class Picture implements java.io.Serializable{ long id; byte[] data; ... // getters and setters } And here's my controller that saves the file on submit: public class PictureUploadFormController extends AbstractBaseFormController{ ... protected ModelAndView onSubmit(HttpServletRequest request, HttpServletResponse response, Object command, BindException errors) throws Exception{ MutlipartFile file; // getting MultipartFile from the command object ... // beginning hibernate transaction ... Picture p=new Picture(); p.setData(file.getBytes()); pictureDAO.makePersistent(p); // this method simply calls getSession().saveOrUpdate(p) // committing hiernate transaction ... } ... } Obviously a bad piece of code. Is there anyway I could use InputStream or Blob to save the data, instead of first loading all the bytes from the user into the memory and then pushing them into the database? I did some research on hibernate's support for Blob, and found this in Hibernate In Action book: java.sql.Blob and java.sql.Clob are the most efficient way to handle large objects in Java. Unfortunately, an instance of Blob or Clob is only useable until the JDBC transaction completes. So if your persistent class defines a property of java.sql.Clob or java.sql.Blob (not a good idea anyway), you’ll be restricted in how instances of the class may be used. In particular, you won’t be able to use instances of that class as detached objects. Furthermore, many JDBC drivers don’t feature working support for java.sql.Blob and java.sql.Clob. Therefore, it makes more sense to map large objects using the binary or text mapping type, assuming retrieval of the entire large object into memory isn’t a performance killer. Note you can find up-to-date design patterns and tips for large object usage on the Hibernate website, with tricks for particular platforms. Now apparently the Blob cannot be used, as it is not a good idea anyway, what else could be used to improve the performance? I couldn't find any up-to-date design pattern or any useful information on Hibernate website. So any help/recommendations from stackoverflowers will be much appreciated. Thanks

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  • Java Garbage Collection

    - by pietervn
    I was wondering about the garbage collection that takes place in Java. Is it really able to handle all objects that aren't used and free up the most possible memory? I also want to know how does the Java garbage collection compare to another language like lets say C#? And then, how does the automatic garbage collection measure up against manual collection from a language like C?

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  • x86 .net application with system.OutOfMemoryException

    - by Allen
    Hi,Guys I got OutOfMemoryException after the app running for 1 day, the app totally use 1.5G memory , all consumed by managed heap, gen 2 used 200mb , and LOB used 1.3mb, however the weired thing is, 900mb of space are Free. from perf counter I saw there had number of gen 2 gc collection happened, why GC collector cannot collect those 900mb free space in gen2 and LOB? I'm really appreicate for your help. following info are from windbg: 0:000> !eeheap -gc Number of GC Heaps: 1 generation 0 starts at 0x183153f0 generation 1 starts at 0x182aa834 generation 2 starts at 0x02131000 ephemeral segment allocation context: none segment begin allocated size 02130000 02131000 0312f284 0xffe284(16769668) 07750000 07751000 0874fc5c 0xffec5c(16772188) 09e30000 09e31000 0ae2fc2c 0xffec2c(16772140) 0b230000 0b231000 0c22ffec 0xffefec(16773100) 0c230000 0c231000 0d22f6f0 0xffe6f0(16770800) 0d230000 0d231000 0e22ea10 0xffda10(16767504) 0e230000 0e231000 0f22c1c4 0xffb1c4(16757188) 10390000 10391000 1138ddf4 0xffcdf4(16764404) 154e0000 154e1000 164da90c 0xff990c(16750860) 34aa0000 34aa1000 35a9dbfc 0xffcbfc(16763900) 7aca0000 7aca1000 7bc9edfc 0xffddfc(16768508) 49760000 49761000 4a75ef64 0xffdf64(16768868) 7bca0000 7bca1000 7cc99bac 0xff8bac(16747436) 17a70000 17a71000 183313fc 0x8c03fc(9176060) Large object heap starts at 0x03131000 segment begin allocated size 03130000 03131000 041250c8 0xff40c8(16728264) 08920000 08921000 099102f8 0xfef2f8(16708344) .... .... 4c760000 4c761000 4d71d578 0xfbc578(16500088) 1bb10000 1bb11000 1ca110d0 0xf000d0(15728848) 57760000 57761000 5862d7f8 0xecc7f8(15517688) Total Size: Size: 0x5ab13450 (1521562704) bytes. ------------------------------ GC Heap Size: Size: 0x5ab13450 (1521562704) bytes. 0:000> !dumpheap -stat total 0 objects Statistics: MT Count TotalSize Class Name 73037c78 1 12 System.Configuration.GenericEnumConverter 73036da0 1 12 System.Configuration.InfiniteIntConverter .... .... 69161c3c 35025 6809420 System.Windows.EffectiveValueEntry[] 69164748 54 12471072 MS.Internal.WeakEventTable+EventKey[] 710e2228 9540 190389260 System.Byte[] 710dd2b8 1317031 339257932 System.String 0035a670 6427 902224056 Free Total 3615631 objects

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  • C programming getting back into it - the red pill

    - by JavaRocky
    Can someone provide recommended reading, website resources or best practices to follow when programming with C. I am a proficient software developer with strong skills in Java and PHP. Is there standard libraries these days which people use? Like what spring is to java? And standard design patterns for managing memory or even standard libraries for that fact? I want to write solid, maintainable C programs. GO THE RED PILL! :P

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  • Is it allowed to load Swing classes in non-EDT thread?

    - by ddimitrov
    After the introduction of Java Memory Model, the Swing guidelines were changed to state that any Swing components need to be instantiated on the EDT in order to avoid non-published instance state. What I could not find anywhere is whether the classloading is also mandated to be on the EDT or can we pre-load key Swing classes in a background thread? Is there any official statement from Sun/Oracle on this? Are there any classes that are known to hold non-threadsafe static state, hence need to be loaded on EDT?

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  • Why is the software world full of status codes?

    - by David V McKay
    Why did programmers ever start using status codes? I mean, I guess I could imagine this might be useful back in the days when a text string was an expensive resource. WAYYY back then. But even after we had megabytes of memory to work with, we continued to use them. What possible advantage could there be for obfuscating the meaning of an error message or status message behind a status code?

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  • Explicit disable MySQL query cache in some parts of program

    - by jack
    In a Django project, some cronjob programs are mainly used for administrative or analysis purposes, e.g. generating site usage stats, rotating user activities log, etc. We probably do not hope MySQL to cache queries in those programs to save memory usage and improve query cache efficiency. Is it possible to turn off MySQL query cache explicitly in those programs while keep it enabled for other parts including all views.py?

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  • Built in Analyzer in Xcode 3.1.4

    - by Mustafa
    Hi all, I wonder if the built in Analyzer in Xcode 3.1.4 makes it redundant to use LLVM/Clang Static Analyzer separately? Please refer to the original article here: Finding memory leaks with the LLVM/Clang Static Analyzer Thanks.

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  • how to create partition on windows CE device

    - by mack369
    Is there any tool to create a new partition on windows CE device? Device has a NAND flash memory and initially there were two partitions. Using Storage manager in Control Panel I was able to delete one partition but when I want to create it again, I get an error message: "Unable to create partition".

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  • Should we denormalize database to improve performance?

    - by Groo
    We have a requirement to store 500 measurements per second, coming from several devices. Each measurement consists of a timestamp, a quantity type, and several vector values. Right now there is 8 vector values per measurement, and we may consider this number to be constant for needs of our prototype project. We are using HNibernate. Tests are done in SQLite (disk file db, not in-memory), but production will probably be MsSQL. Our Measurement entity class is the one that holds a single measurement, and looks like this: public class Measurement { public virtual Guid Id { get; private set; } public virtual Device Device { get; private set; } public virtual Timestamp Timestamp { get; private set; } public virtual IList<VectorValue> Vectors { get; private set; } } Vector values are stored in a separate table, so that each of them references its parent measurement through a foreign key. We have done a couple of things to ensure that generated SQL is (reasonably) efficient: we are using Guid.Comb for generating IDs, we are flushing around 500 items in a single transaction, ADO.Net batch size is set to 100 (I think SQLIte does not support batch updates? But it might be useful later). The problem Right now we can insert 150-200 measurements per second (which is not fast enough, although this is SQLite we are talking about). Looking at the generated SQL, we can see that in a single transaction we insert (as expected): 1 timestamp 1 measurement 8 vector values which means that we are actually doing 10x more single table inserts: 1500-2000 per second. If we placed everything (all 8 vector values and the timestamp) into the measurement table (adding 9 dedicated columns), it seems that we could increase our insert speed up to 10 times. Switching to SQL server will improve performance, but we would like to know if there might be a way to avoid unnecessary performance costs related to the way database is organized right now. [Edit] With in-memory SQLite I get around 350 items/sec (3500 single table inserts), which I believe is about as good as it gets with NHibernate (taking this post for reference: http://ayende.com/Blog/archive/2009/08/22/nhibernate-perf-tricks.aspx). But I might as well switch to SQL server and stop assuming things, right? I will update my post as soon as I test it.

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  • How do access a secure website within a sharepoint webpart?

    - by Bill
    How do access a secure website within a sharepoint webpart? The following code works fine as a console application but if you run it in a webpart, you will get a access violation WebRequest request = WebRequest.Create("https://somesecuresite.com"); WebResponse firstResponse = null; try { firstResponse = request.GetResponse(); } catch (WebException ex) { writer.WriteLine("Error: " + ex.ToString()); return; } if you access a non secure site, it also works. Any ideas? Error: System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a receive. --- System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. at System.Net.UnsafeNclNativeMethods.NativePKI.CertVerifyCertificateChainPolicy(IntPtr policy, SafeFreeCertChain chainContext, ChainPolicyParameter& cpp, ChainPolicyStatus& ps) at System.Net.PolicyWrapper.VerifyChainPolicy(SafeFreeCertChain chainContext, ChainPolicyParameter& cpp) at System.Net.Security.SecureChannel.VerifyRemoteCertificate(RemoteCertValidationCallback remoteCertValidationCallback) at System.Net.Security.SslState.CompleteHandshake() at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult) at System.Net.TlsStream.CallProcessAuthentication(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result) at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.Net.ConnectStream.WriteHeaders(Boolean async) --- End of inner exception stack trace --- at System.Net.HttpWebRequest.GetResponse()

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  • Event sourcing: Write event before or after updating the model

    - by Magnus
    I'm reasoning about event sourcing and often I arrive at a chicken and egg problem. Would be grateful for some hints on how to reason around this. If I execute all I/O-bound processing async (ie writing to the event log) then how do I handle, or sometimes even detect, failures? I'm using Akka Actors so processing is sequential for each event/message. I do not have any database at this time, instead I would persist all the events in an event log and then keep an aggregated state of all the events in a model stored in memory. Queries are all against this model, you can consider it to be a cache. Example Creating a new user: Validate that the user does not exist in model Persist event to journal Update model (in memory) If step 3 breaks I still have persisted my event so I can replay it at a later date. If step 2 breaks I can handle that as well gracefully. This is fine, but since step 2 is I/O-bound I figured that I should do I/O in a separate actor to free up the first actor for queries: Updating a user while allowing queries (A0 = Front end/GUI actor, A1 = Processor Actor, A2 = IO-actor, E = event bus). (A0-E-A1) Event is published to update user 'U1'. Validate that the user 'U1' exists in model (A1-A2) Persist event to journal (separate actor) (A0-E-A1-A0) Query for user 'U1' profile (A2-A1) Event is now persisted continue to update model (A0-E-A1-A0) Query for user 'U1' profile (now returns fresh data) This is appealing since queries can be processed while I/O-is churning along at it's own pace. But now I can cause myself all kinds of problems where I could have two incompatible commands (delete and then update) be persisted to the event log and crash on me when replayed up at a later date, since I do the validation before persisting the event and then update the model. My aim is to have a simple reasoning around my model (since Actor processes messages sequentially single threaded) but not be waiting for I/O-bound updates when Querying. I get the feeling I'm modeling a database which in itself is might be a problem. If things are unclear please write a comment.

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  • T-SQL query with date range

    - by Moo
    Hi, I have a fairly weird 'bug' with a simple query, and I vaguely remember reading the reason for it somewhere a long time ago but would love someone to refresh my memory. The table is a basic ID, Datetime table. The query is: select ID, Datetime from Table where Datetime <= '2010-03-31 23:59:59' The problem is that the query results include results where the Datetime is '2010-04-01 00:00:00'. The next day. Which it shouldn't. Anyone? Cheers Moo

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  • Subclassing NSObject, can it cause problems?

    - by Sheehan Alam
    I have a very basic data class that is subclassed from NSObject. I declare a few strings, make sure they have properties (nonatomic, copy), and synthesize them. The only method I implemented was dealloc() which releases my strings. Can any memory problems arise from just this? Are there any other methods I need to implement?

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  • Is there something like the OllyDbg / SoftICE disassembler + debugger for java?

    - by Ran Biron
    Is there a utility similar to OllyDbg / SoftICE for java? I.e. execute class (from jar / with class path) and, without source code, show the disassembly of the intermediate code with ability to step through / step over / search for references / edit specific intermediate code in memory / apply edit to file... If not, is it even possible to write something like this (assuming we're willing to live without hotspot for the debug duration)?

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  • Good Postgres graphical client for Windows

    - by alex
    The name pretty much says it all. Right now I'm using Squirrel - it crashes frequently and suffers from memory problems (I've tried increasing the heap size). I don't need anything particularly fancy or full-featured - just something that won't take up 2.4 GB of RAM to store a 1.5 million line, 8 column result set.

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  • Is It Possible to get a (rough) Mobile Phone Location from a HTTP Request

    - by Tim Lytle
    If memory serves me correctly, google does this for the maps site. I know google's mobile maps app can determine the rough location (I assume using some kind of cell tower lookup), yet I seem to remember the site getting somewhat close to the current location when viewing on a mobile browser. Anyone know how/if that's possible? Does the IP address change based on the tower or area (seems like they'd be using some kind of gateway common to the carrier)?

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  • Flex maps howto examples

    - by alessandro ferrucci
    Hello, I've stumbled upon this flash map http://www.washingtonpost.com/wp-srv/special/nation/unemployment-by-county/ it looks like they used this map to construct the website. http://commons.wikimedia.org/wiki/File:USA_Counties_with_FIPS_and_names.svg I am curious as to what people have done or any blogs that describe what can be done with flex and simple maps like this (not google maps style maps) but simple all-in-memory maps like this one. It would be cool to see what/ and how flex can do in terms of maps. thanks!

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  • Summary of the last decade of garbage collection?

    - by Ben Karel
    I've been reading through the Jones & Lin book on garbage collection, which was published in 1996. Obviously, the computing world has changed dramatically since then: multicore, out-of-order chips with large caches, and even larger main memory in desktops. The world has also more-or-less settled on the x86 and ARM microarchitectures for most consumer-facing systems. How has the field of garbage collection changed since the seminal book was published?

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  • flash game lags every 20 seg

    - by ZoserLock
    My game has delta time for frame independent movement, at 250 fps run perfectly smooth, but if i limit the fps to 60, the game slow down for a 2-4 seg every 20 seg aprox, even in small programs i have this same problem. no memory is created or released i comment everything i can and the problem persist thanks and sorry for my english

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  • Dropping PendingIntents

    - by Jeremy Edwards
    Is it ok to drop PendingIntents in android if they are never used. Such as in an AppWidgetProvider where a PendingIntent that was never used be overwritten by a new PendingIntent. Or should we call cancel on all unused PendingIntents to clean up memory appropriately?

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  • OpenGL particle system

    - by allan
    I'm really new with OpenGL, so bear with me. I'm trying to simulate a particle system using OpenGl but I can't get it to work, this is what I have so far: #include <GL/glut.h> int main (int argc, char **argv){ // data allocation, various non opengl stuff ............ glutInit(&argc, argv); glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE ); glutInitWindowPosition(100,100); glutInitWindowSize(size, size); glPointSize (4); glutCreateWindow("test gl"); ............ // initial state, not opengl ............ glViewport(0,0,size,size); glutDisplayFunc(display); glutIdleFunc(compute); glutMainLoop(); } void compute (void) { // change state not opengl glutPostRedisplay(); } void display (void) { glClear(GL_COLOR_BUFFER_BIT); glBegin(GL_POINTS); for(i = 0; i<nparticles; i++) { // two types of particles if (TYPE(particle[i]) == 1) glColor3f(1,0,0); else glColor3f(0,0,1); glVertex2f(X(particle[i]),Y(particle[i])); } glEnd(); glFlush(); glutSwapBuffers(); } I get a black window after a couple of seconds (the window has just the title bar before that). Where do I go wrong? Any help would be very much appreciated. Thanks. LE: the x and y coordinates of each particle are within the interval (0,size)

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