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• Problem of Sprites and labels are displayed by white boxes.

  - by srikanth rongali

  I am writing a game in cocos2d. I am using a function restartDirector in AppDelegate class. -(void)restartDirector{ [[CCDirector sharedDirector] end]; [[CCDirector sharedDirector] release]; if( ! [CCDirector setDirectorType:CCDirectorTypeDisplayLink] ) [CCDirector setDirectorType:CCDirectorTypeDefault]; [[CCDirector sharedDirector] setPixelFormat:kPixelFormatRGBA8888]; [CCTexture2D setDefaultAlphaPixelFormat:kTexture2DPixelFormat_RGBA8888]; [[CCDirector sharedDirector] setAnimationInterval:1.0/60]; [[CCDirector sharedDirector] setDisplayFPS:YES]; [[CCDirector sharedDirector] setDeviceOrientation:CCDeviceOrientationLandscapeLeft]; [[CCDirector sharedDirector] attachInView:window]; } This function I called in one of the game Scene . -(void)PracticeMethod:(id)sender { [MY_DELEGATE restartDirector]; CCScene *endPageScene = [CCScene node]; CCLayer *endPageLayer = [DummyScene node]; [endPageScene addChild:endPageLayer]; [[CCDirector sharedDirector] runWithScene:endPageScene]; // [[CCDirector sharedDirector] replaceScene:endPageScene]; } When used the replaceScene, there is no problem in game but the memory of abject allocation is high(I checked in leaks tool). So I used runWithScene. But , while using these when the scene DummyScene is loaded the sprites, labels in it are displayed by white boxes. I cannot see the sprites and labels. If I am using replaceScene everything thing is working fine but the memory allocation is high. this is my problem. Thank you.

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• jQuery "best practices" is an oxymoron [closed]

  - by n00b

  jQuery "best practices", oxymoron for several reasons sadly To speak candidly, the entire jQuery library has a HIGHLY inconsistent API, and virtually no coding standards. It's basically a subset of JavaScript, a new language if you will, which is probably the most confusing part for normal javascript developers. In my opinion, use normal JavaScript where possible to save on memory consumption. Or, better yet, use a professional tool like YUI. If you already come from a javascript background, you will appreciate it much more than jQuery because it doesn't have n00b wrappers around everything. In tools like YUI, you interact directly with the native DOM to do things, instead of a super-jQuery object that tries to do everything. I'll get voted down for saying the truth. Don't get me wrong, jQuery is cool if you wanna throw something flashy up quick, but if you're going to build a larger app you're going to need a more refined tool (especially since jQuery leaks memory like no other once you start chaining too much things). jQuery does have one of the lowest learning curves, and you won't outgrow it for awhile, but when you do it will be highly apparent and tedious to merge to something else. over 60 years programming experience someone clean this up and community wiki please

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• C++ polymorphism and slicing

  - by Draco Ater

  The following code, prints out Derived Base Base But I need every Derived object put into User::items, call its own print function, but not the base class one. Can I achieve that without using pointers? If it is not possible, how should I write the function that deletes User::items one by one and frees memory, so that there should not be any memory leaks? #include <iostream> #include <vector> #include <algorithm> using namespace std; class Base{ public: virtual void print(){ cout << "Base" << endl;} }; class Derived: public Base{ public: void print(){ cout << "Derived" << endl;} }; class User{ public: vector<Base> items; void add_item( Base& item ){ item.print(); items.push_back( item ); items.back().print(); } }; void fill_items( User& u ){ Derived d; u.add_item( d ); } int main(){ User u; fill_items( u ); u.items[0].print(); }

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• Bash PATH: How long is too long?

  - by ajwood

  Hi, I'm currently designing a software quarantine pattern to use on Ubuntu. I'm not sure how standard "quarantine" is in this context, so here is what I hope to accomplish... Inside a particular quarantine is all of the stuff one needs to run an application (bin, share, lib, etc.). Ideally, the quarantine has no leaks, which means it's not relying on any code outside of itself on the system. A quarantine can be defined as a set of executables (and some environment settings needed to make them run). I think it will be beneficial to separate the built packages enough such that upgrading to a newer version of the quarantine won't require rebuilding the whole thing. I'll be able to update just a few packages, and then the new quarantine can use some of old parts and some of the new parts. One issue I'm wondering about is the environment variables I'll be setting up to use a particular quarantines. Is there a hard limit on how big PATH can be? (either in number of characters, or in the number of directories it contains) Might a path be so long that it affects performance? Thanks very much, Andrew p.s. Any other wisdom that might help my design would be greatly appreciated :)

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• Porting Symbian C++ to Android NDK

  - by Donal Rafferty

  I've been given some Symbian C++ code to port over for use with the Android NDK. The code has lots of Symbian specific code in it and I have very little experience of C++ so its not going very well. The main thing that is slowing me down is trying to figure out the alternatives to use in normal C++ for the Symbian specific code. At the minute the compiler is throwing out all sorts of errors for unrecognised types. From my recent research these are the types that I believe are Symbian specific: TInt, TBool, TDesc8, RSocket, TInetAddress, TBuf, HBufc, RPointerArray Changing TInt and TBool to int and bool respectively works in the compiler but I am unsure what to use for the other types? Can anyone help me out with them? Especially TDesc, TBuf, HBuf. Also Symbian has a two phase contructor using NewL and NewLc But would changing this to a normal C++ constructor be ok? Finally Symbian uses the clean up stack to help eliminate memory leaks I believe, would removing the clean up stack code be acceptable, I presume it should be replaced with try/catch statements?

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• Javascript memory leak/ performance issue?

  - by Tom

  I just cannot for the life of me figure out this memory leak in Internet Explorer. insertTags simple takes string str and places each word within start and end tags for HTML (usually anchor tags). transliterate is for arabic numbers, and replaces normal numbers 0-9 with a &#..n; XML identity for their arabic counterparts. fragment = document.createDocumentFragment(); for (i = 0, e = response.verses.length; i < e; i++) { fragment.appendChild((function(){ p = document.createElement('p'); p.setAttribute('lang', (response.unicode) ? 'ar' : 'en'); p.innerHTML = ((response.unicode) ? (response.surah + ':' + (i+1)).transliterate() : response.surah + ':' + (i+1)) + ' ' + insertTags(response.verses[i], '<a href="#" onclick="window.popup(this);return false;" class="match">', '</a>'); try { return p } finally { p = null; } })()); } params[0].appendChild( fragment ); fragment = null; I would love some links other than MSDN and about.com, because neither of them have sufficiently explained to me why my script leaks memory. I am sure this is the problem, because without it everything runs fast (but nothing displays). I've read that doing a lot of DOM manipulations can be dangerous, but the for loops a max of 286 times (# of verses in surah 2, the longest surah in the Qur'an).

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• Outlook VSTO AddIn for Meetings

  - by BigDubb

  We have created a VSTO addin for Outlook Meetings. As part of this we trap on the SendEvent of the message on the FormRegionShowing event: _apptEvents.Send += new Microsoft.Office.Interop.Outlook.ItemEvents_SendEventHandler(_apptEvents_Send); The method _apptEvents_Send then tests on a couple of properties and exits where appropriate. private void _apptEvents_Send(ref bool Cancel) { if (!_Qualified) { MessageBox.Show("Meeting has not been qualified", "Not Qualified Meeting", MessageBoxButtons.OK, MessageBoxIcon.Information); chkQualified.Focus(); Cancel = true; } } The problem that we're having is that some users' messages get sent twice. Once when the meeting is sent and a second time when the user re-opens outlook. I've looked for memory leaks, thinking that something might not be getting disposed of properly, and have added explicit object disposal on all finally calls to try and make sure resources are managed, but still getting the functionality incosistently across the organization. i.e. I never encountered the problem during development, nor other developers during testing. All users are up to date on framework (3.5 SP1) and Hotfixes for Outlook. Does anyone have any ideas on what might be causing this? Any ideas anyone might have would be greatly appreciated.

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• Android Signal 11 (SIGSEGV)

  - by Naturjoghurt

  I read many posts here and on other sites, but can not find the problem creating my Error: I use an AsyncTask because I want to easily manipulate the UI Thread before and after Execution. In doInBackground I create a ThreadPoolExecutor and execute Runnables. If I only execute 1 Runnable with the Executor, there is no Problem, but if I execute another Runnable I get following Error: 06-26 18:00:42.288: A/libc(25073): Fatal signal 11 (SIGSEGV) at 0x7f486162 (code=1), thread 25106 (pool-1-thread-2) 06-26 18:00:42.304: D/dalvikvm(25073): GC_CONCURRENT freed 119K, 2% free 8908K/9056K, paused 4ms+4ms, total 45ms 06-26 18:00:42.327: I/System.out(25073): In Check All with Prefix: a and Length: 4 06-26 18:00:42.390: I/DEBUG(126): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** 06-26 18:00:42.390: I/DEBUG(126): Build fingerprint: 'google/yakju/maguro:4.2.2/JDQ39/573038:user/release-keys' 06-26 18:00:42.390: I/DEBUG(126): Revision: '9' 06-26 18:00:42.390: I/DEBUG(126): pid: 25073, tid: 25106, name: pool-1-thread-2 >>> de.uni_duesseldorf.cn.distributed_computing2 <<< 06-26 18:00:42.390: I/DEBUG(126): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 7f486162 ... 06-26 18:00:42.538: I/DEBUG(126): memory map around fault addr 7f486162: 06-26 18:00:42.538: I/DEBUG(126): 60292000-60391000 06-26 18:00:42.538: I/DEBUG(126): (no map for address) 06-26 18:00:42.538: I/DEBUG(126): bed14000-bed35000 [stack] I set up the ThreadPoolExecutor like this: // numberOfPackages: Number of Runnables to be executed public void initializeThreadPoolExecutor (int numberOfPackages) { int corePoolSize = Runtime.getRuntime().availableProcessors(); int maxPoolSize = numberOfPackages; long keepAliveTime = 60; final BlockingQueue workingQueue = new LinkedBlockingQueue(); executor = new ThreadPoolExecutor(corePoolSize, maxPoolSize, keepAliveTime, TimeUnit.SECONDS, workingQueue); } I have no clue, why it fails when starting the second Thread. Maybe Memory Leaks? Any Help appreciated. Thanks in Advance

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• How to differentiate between exceptions i can show the user, and ones i can't?

  - by Ian Boyd

  i have some business logic that traps some logically invalid situations, e.g. trying to reverse a transaction that was already reversed. In this case the correct action is to inform the user: Transaction already reversed or Cannot reverse a reversing transaction or You do not have permission to reverse transactions or This transaction is on a session that has already been closed or This transaction is too old to be reversed The question is, how do i communicate these exceptional cases back to the calling code, so they can show the user? Do i create a separate exception for each case: catch (ETransactionAlreadyReversedException) MessageBox.Show('Transaction already reversed') catch (EReversingAReversingTransactionException) MessageBox.Show('Cannot reverse a reversing transaction') catch (ENoPermissionToReverseTranasctionException) MessageBox.Show('You do not have permission to reverse transactions') catch (ECannotReverseTransactionOnAlredyClosedSessionException) MessageBox.Show('This transaction is on a session that has already been closed') catch (ECannotReverseTooOldTransactionException) MessageBox.Show('This transaction is too old to be reversed') Downside for this is that when there's a new logical case to show the user: Tranasctions created by NSL cannot be reversed i don't simply show the user a message, and instead it leaks out as an unhandled excpetion, when really it should be handled with another MessageBox. The alternative is to create a single exception class: `EReverseTransactionException` With the understanding that any exception of this type is a logical check, that should be handled with a message box: catch (EReverseTransactionException) But it's still understood that any other exceptions, ones that involve, for example, an memory ECC parity error, continue unhandled. In other words, i don't convert all errors that can be thrown by the ReverseTransaction() method into EReverseTransactionException, only ones that are logically invalid cause of the user.

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• Overlaying several CLR reference fields with each other in explicit struct?

  - by thr

  Edit: I'm well aware of that this works very well with value types, my specific question is about using this for reference types. I've been tinkering around with structs in .NET/C#, and I just found out that you can do this: using System; using System.Runtime.InteropServices; namespace ConsoleApplication1 { class Foo { } class Bar { } [StructLayout(LayoutKind.Explicit)] struct Overlaid { [FieldOffset(0)] public object AsObject; [FieldOffset(0)] public Foo AsFoo; [FieldOffset(0)] public Bar AsBar; } class Program { static void Main(string[] args) { var overlaid = new Overlaid(); overlaid.AsObject = new Bar(); Console.WriteLine(overlaid.AsBar); overlaid.AsObject = new Foo(); Console.WriteLine(overlaid.AsFoo); Console.ReadLine(); } } } Basically circumventing having to do dynamic casting during runtime by using a struct that has an explicit field layout and then accessing the object inside as it's correct type. Now my question is: Can this lead to memory leaks somehow, or any other undefined behavior inside the CLR? Or is this a fully supported convention that is usable without any issues? I'm aware that this is one of the darker corners of the CLR, and that this technique is only a viable option in very few specific cases.

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• Creating UIButtons

  - by Ralphonzo

  During loadView I am creating 20 UIButtons that I would like to change the title text of depending on the state of a UIPageControl. I have a pre-save plist that is loaded into a NSArray called arrChars on the event of the current page changing, I set the buttons titles to their relevant text title from the array. The code that does this is: for (int i = 1; i < (ButtonsPerPage + 1); i++) { UIButton *uButton = (UIButton *)[self.view viewWithTag:i]; if(iPage == 1) { iArrPos = (i - 1); } else { iArrPos = (iPage * ButtonsPerPage) + (i - 1); } [uButton setAlpha:0]; NSLog(@"Trying: %d of %d", iArrPos, [self.arrChars count]); if (iArrPos >= [self.arrChars count]) { [uButton setTitle: @"" forState: UIControlStateNormal]; } else { NSString *value = [[NSString alloc] initWithFormat:@"%@", [self.arrChars objectAtIndex:iArrPos]]; NSLog(@"%@", value); [uButton setTitle: [[NSString stringWithFormat:@"%@", value] forState: UIControlStateNormal]; [value release]; //////Have tried: //////[uButton setTitle: value forState: UIControlStateNormal]; //////Have also tried: //////[uButton setTitle: [self.arrChars objectAtIndex:iArrPos] forState: UIControlStateNormal]; //////Have also also tried: //////[uButton setTitle: [[self.arrChars objectAtIndex:iArrPos] autorelease] forState: UIControlStateNormal]; } [uButton setAlpha:1]; } When setting the Title of a button it does not appear to be autoreleasing the previous title and the allocation goes up and up. What am I doing wrong? I have been told before that tracking things by allocations is a bad way to chase leaks because as far as I can see, the object is not leaking in Instruments but my total living allocations continue to climb until I get a memory warning. If there is a better way to track there I would love to know.

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• free( ) pointers

  - by user1043625

  I'm required to use a special library to keep track of my memory leaks where malloc()= allocate( ) and free( ) = unallocate( ). I'm trying to complete free a linked-list but it seems like the "root" value isn't being freed. typedef struct _node { struct _node *child; char *command; } Command_list; void delete_commands(Command_list **root) { Command_list *temp; while( *root != NULL ){ temp = (*root)->child; //printf("STRING: %s\n", *root->command ); unallocate( *root ); *root = temp; } } The function that's calling it void file_processing( .... ){ Command_list *root = allocate(sizeof (Command_list)); root = NULL; .... delete_commands( &root ); } } I believe that Command_list *root = allocate(sizeof (Command_list)) isn't being properly de-allocated for some reason. Anyone can give me some hints? UPDATE: I found out that instead of Command_list *root = allocate(sizeof (Command_list)); root = NULL; this works: Command_list *root = NULL;

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• Adding images to an array memory issue

  - by Friendlydeveloper

  Hello all, I'm currently facing the following issue: My app dynamically creates images (320 x 480 pixels) and adds them to a NSMutableArray. I need those images inside that array in order to allow users to browse through them back and forth. I only need to keep the latest 5 images. So I wrote a method like below: - (void)addImageToArray:(UIImage*)theImage { if ([myMutableArray count] < 5) { [myMutableArray addObject:theImage]; } else { [myMutableArray removeObjectAtIndex:0]; [myMutableArray addObject:theImage]; } } This method basically does what it's supposed to do. However, in instruments I can see, that memory usage is permanently incrementing. At some point, even though I do not have any memory leaks, the app finally crashes. The way I see it, XCode does remove the image from my array, but does not release it. Is there a way I can make sure, that the object I want to remove from my array will also get released? Maybe my approach is completely wrong and I need to find a different way. Any help appreciated. Thanks in advance

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• A temporary disagreement

  - by Tony Davis

  Last month, Phil Factor caused a furore amongst some MVPs with an article that attempted to offer simple advice to developers regarding the use of table variables, versus local and global temporary tables, in their code. Phil makes clear that the table variables do come with some fairly major limitations.no distribution statistics, no parallel query plans for queries that modify table variables.but goes on to suggest that for reasonably small-scale strategic uses, and with a bit of due care and testing, table variables are a "good thing". Not everyone shares his opinion; in fact, I imagine he was rather aghast to learn that there were those felt his article was akin to pulling the pin out of a grenade and tossing it into the database; table variables should be avoided in almost all cases, according to their advice, in favour of temp tables. In other words, a fairly major feature of SQL Server should be more-or-less 'off limits' to developers. The problem with temp tables is that, because they are scoped either in the procedure or the connection, it is easy to allow them to hang around for too long, eating up precious memory and bulking up the shared tempdb database. Unless they are explicitly dropped, global temporary tables, and local temporary tables created within a connection rather than within a stored procedure, will persist until the connection is closed or, with connection pooling, until the connection is reused. It's also quite common with ASP.NET applications to have connection leaks, as Bill Vaughn explains in his chapter in the "SQL Server Deep Dives" book, meaning that the web page exits without closing the connection object, maybe due to an error condition. This will then hang around in the heap for what might be hours before picked up by the garbage collector. Table variables are much safer in this regard, since they are batch-scoped and so are cleaned up automatically once the batch is complete, which also means that they are intuitive to use for the developer because they conform to scoping rules that are closer to those in procedural code. On the surface then, an ideal way to deal with issues related to tempdb memory hogging. So why did Phil qualify his recommendation to use Table Variables? This is another of those cases where, like scalar UDFs and table-valued multi-statement UDFs, developers can sometimes get into trouble with a relatively benign-looking feature, due to way it's been implemented in SQL Server. Once again the biggest problem is how they are handled internally, by the SQL Server query optimizer, which can make very poor choices for JOIN orders and so on, in the absence of statistics, especially when joining to tables with highly-skewed data. The resulting execution plans can be horrible, as will be the resulting performance. If the JOIN is to a large table, that will hurt. Ideally, Microsoft would simply fix this issue so that developers can't get burned in this way; they've been around since SQL Server 2000, so Microsoft has had a bit of time to get it right. As I commented in regard to UDFs, when developers discover issues like with such standard features, the database becomes an alien planet to them, where death lurks around each corner, and they continue to avoid these "killer" features years after the problems have been eventually resolved. In the meantime, what is the right approach? Is it to say "hammers can kill, don't ever use hammers", or is it to try to explain, as Phil's article and follow-up blog post have tried to do, what the feature was intended for, why care must be applied in its use, and so enable developers to make properly-informed decisions, without requiring them to delve deep into the inner workings of SQL Server? Cheers, Tony.

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• ORA-4031 Troubleshooting

  - by [email protected]

    QUICKLINK: Note 396940.1 Troubleshooting and Diagnosing ORA-4031 Error Note 1087773.1 : ORA-4031 Diagnostics Tools [Video]   Have you observed an ORA-04031 error reported in your alert log? An ORA-4031 error is raised when memory is unavailable for use or reuse in the System Global Area (SGA).  The error message will indicate the memory pool getting errors and high level information about what kind of allocation failed and how much memory was unavailable.  The challenge with ORA-4031 analysis is that the error and associated trace is for a "victim" of the problem.   The failing code ran into the memory limitation, but in almost all cases it was not part of the root problem.    Looking for the best way to diagnose? When an ORA-4031 error occurs, a trace file is raised and noted in the alert log if the process experiencing the error is a background process.   User processes may experience errors without reports in the alert log or traces generated.   The V$SHARED_POOL_RESERVED view will show reports of misses for memory over the life of the database. Diagnostics scripts are available in Note 430473.1 to help in analysis of the problem.  There is also a training video on using and interpreting the script data Note 1087773.1. 11g DiagnosabilityStarting with Oracle Database 11g Release 1, the Diagnosability infrastructure was introduced which places traces and core files into a location controlled by the DIAGNOSTIC_DEST initialization parameter when an incident, such as an ORA-4031 occurs. For earlier versions, the trace file will be written to either USER_DUMP_DEST (if the error was caught in a user process) or BACKGROUND_DUMP_DEST (if the error was caught in a background process like PMON or SMON). The trace file contains vital information about what led to the error condition.  Note 443529.1 11g Quick Steps to Package and Send Critical Error Diagnostic Information to Support[Video]Oracle Configuration Manager (OCM)Oracle Configuration Manager (OCM) works with My Oracle Support to enable proactive support capability that helps you organize, collect and manage your Oracle configurations.Oracle Configuration Manager Quick Start GuideNote 548815.1: My Oracle Support Configuration Management FAQ Note 250434.1: BULLETIN: Learn More About My Oracle Support Configuration Manager    Common Causes/Solutions The ORA-4031 can occur for many different reasons.  Some possible causes are: SGA components too small for workload Auto-tuning issues Fragmentation due to application design Bug/leaks in memory allocationsFor more on the 4031 and how this affects the SGA, see Note 396940.1 Troubleshooting and Diagnosing ORA-4031 Error Because of the multiple potential causes, it is important to gather enough diagnostics so that an appropriate solution can be identified.  However, most commonly the cause is associated with configuration tuning.   Ensuring that MEMORY_TARGET or SGA_TARGET are large enough to accommodate workload can get around many scenarios.  The default trace associated with the error provides very high level information about the memory problem and the "victim" that ran into the issue.   The data in the default trace is not going to point to the root cause of the problem. When migrating from 9i to 10g and higher, it is necessary to increase the size of the Shared Pool due to changes in the basic design of the shared memory area. Note 270935.1 Shared pool sizing in 10gNOTE: Diagnostics on the errors should be investigated as close to the time of the error(s) as possible.  If you must restart a database, it is not feasible to diagnose the problem until the database has matured and/or started seeing the problems again. Note 801787.1 Common Cause for ORA-4031 in 10gR2, Excess "KGH: NO ACCESS" Memory Allocation ***For reference to the content in this blog, refer to Note.1088239.1 Master Note for Diagnosing ORA-4031 

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• links for 2010-12-23

  - by Bob Rhubart

  Oracle VM Virtualbox 4.0 extension packs (Wim Coekaerts Blog) Wim Coekaerts describes the the new extension pack in Oracle VM Virtualbox 4.0 and how it's different from 3.2 and earlier releases. (tags: oracle otn virtualization virtualbox) Oracle Fusion Middleware Security: Creating OES SM instances on 64 bit systems "I've already opened a bug on this against OES 10gR3 CP5, but in case anyone else runs into it before it gets fixed I wanted to blog it too. (NOTE: CP5 is when official support was introduced for running OES on a 64 bit system with a 64 bit JVM)" - Chris Johnson (tags: oracle otn fusionmiddleware security) Oracle Enterprise Manager Grid Control: Shared loader directory, RAC and WebLogic Clustering "RAC is optional. Even the load balancer is optional. The feed from the agents also goes to the load balancer on a different port and it is routed to the available management server. In normal case, this is ok." - Porus Homi Havewala (tags: WebLogic oracle otn grid clustering) Magic Web Doctor: Thought Process on Upgrading WebLogic Server to 11g "Upgrading to new versions can be challenging task, but it's done for linear scalability, continuous enhanced availability, efficient manageability and automatic/dynamic infrastructure provisioning at a low cost." - Chintan Patel (tags: oracle otn weblogic upgrading) InfoQ: Using a Service Bus to Connect the Supply Chain Peter Paul van de Beek presents a case study of using a service bus in a supply channel connecting a wholesale supplier with hundreds of retailers, the overall context and challenges faced – including the integration of POS software coming from different software providers-, the solution chosen and its implementation, how it worked out and the lessons learned along the way. (tags: ping.fm) Oracle VM VirtualBox 4.0 is released! - The Fat Bloke Sings The Fat Bloke spreads the news and shares some screenshots.  (tags: oracle otn virtualization virtualbox) Leaks on Wikis: "Corporations...You're Next!" Oracle Desktop Virtualization Can Help. (Oracle's Virtualization Blog) "So what can you do to guard against these types of breaches where there is no outsider (or even insider) intrusion to detect per se, but rather someone with malicious intent is physically walking out the door with data that they are otherwise allowed to access in their daily work?" - Adam Hawley (tags: oracle otn virtualization security) OTN ArchBeat Podcast Guest Roster As the OTN ArchBeat Podcast enters its third year, it's time to acknowledge the invaluable contributions of the guests who have participated in ArchBeat programs. Check out this who's who of ArchBeat podcast panelists, with links to their respective interviews and more. (tags: oracle otn oracleace podcast archbeat) Show Notes: Architects in the Cloud (ArchBeat) Now available! Part 2 (of 4) of the ArchBeat interview with Stephen G. Bennett and Archie Reed, the authors of "Silver Clouds, Dark Linings: A Concise Guide to Cloud Computing." (tags: oracle otn podcast cloud) A Cautionary Tale About Multi-Source JNDI Configuration (Scott Nelson's Portal Productivity Ponderings) "I ran into this issue after reading that p13nDataSource and cgDataSource-NonXA should not be configured as multi-source. There were some issues changing them to use the basic JDBC connection string and when rolling back to the bad configuration the server went 'Boom.'" - Scott Nelson (tags: weblogic jdbc oracle jndi)

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• Heterogeneous Datacenter Management with Enterprise Manager 12c

  - by Joe Diemer

  The following is a Guest Blog, contributed by Bryce Kaiser, Product Manager at Blue MedoraWhen I envision a perfect datacenter, it would consist of technologies acquired from a single vendor across the entire server, middleware, application, network, and storage stack - Apps to Disk - that meets your organization’s every IT requirement with absolute best-of-breed solutions in every category.   To quote a familiar motto, your datacenter would consist of "Hardware and Software, Engineered to Work Together".  In almost all cases, practical realities dictate something far less than the IT Utopia mentioned above.   You may wish to leverage multiple vendors to keep licensing costs down, a single vendor may not have an offering in the IT category you need, or your preferred vendor may quite simply not have the solution that meets your needs.    In other words, your IT needs dictate a heterogeneous IT environment.  Heterogeneity, however, comes with additional complexity. The following are two pretty typical challenges:1) No End-to-End Visibility into the Enterprise Wide Application Deployment. Each vendor solution which is added to an infrastructure may bring its own tooling creating different consoles for different vendor applications and platforms.2) No Visibility into Performance Bottlenecks. When multiple management tools operate independently, you lose diagnostic capabilities including identifying cross-tier issues with database, hung-requests, slowness, memory leaks and hardware errors/failures causing DB/MW issues. As adoption of Oracle Enterprise Manager (EM) has increased, especially since the release of Enterprise Manager 12c, Oracle has seen an increase in the number of customers who want to leverage their investments in EM to manage non-Oracle workloads.  Enterprise Manager provides a single pane of glass view into their entire datacenter.  By creating a highly extensible framework via the Oracle EM Extensibility Development Kit (EDK), Oracle has provided the tooling for business partners such as my company Blue Medora as well as customers to easily fill gaps in the ecosystem and enhance existing solutions.  As mentioned in the previous post on the Enterprise Manager Extensibility Exchange, customers have access to an assortment of Oracle and Partner provided solutions through this Exchange, which is accessed at http://www.oracle.com/goto/emextensibility.  Currently, there are over 80 Oracle and partner provided plug-ins across the EM 11g and EM 12c versions.  Blue Medora is one of those contributing partners, for which you will find 3 of our solutions including our flagship plugin for VMware.  Let's look at Blue Medora’s VMware plug-in as an example to what I'm trying to convey.  Here is a common situation solved by true visibility into your entire stack:Symptoms•    My database is bogging down, however the database appears okay internally.  Maybe it’s starved for resources?•    My OS tooling is showing everything is “OK”.  Something doesn’t add up. Root cause•    Through the VMware plugin we can see the problem is actually on the virtualization layer Solution•    From within Enterprise Manager  -- the same tool you use for all of your database tuning -- we can overlay the data of the database target, host target, and virtual machine target for a true picture of the true root cause. Here is the console view: Perhaps your monitoring conditions are more specific to your environment.  No worries, Enterprise Manager still has you covered.  With Metric Extensions you have the “Next Generation” of User-Defined Metrics, which easily bring the power of your existing management scripts into a single console while leveraging the proven Enterprise Manager framework. Simply put, Oracle Enterprise manager boasts a growing ecosystem that provides the single pane of glass for your entire datacenter from the database and beyond.  Bryce can be contacted at [email protected]

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• RemoveHandler Issues with Custom Events

  - by Jeff Certain

  This is a case of things being more complicated that I thought they should be. Since it took a while to figure this one out, I thought it was worth explaining and putting all of the pieces to the answer in one spot. Let me set the stage. Architecturally, I have the notion of generic producers and consumers. These put items onto, and remove items from, a queue. This provides a generic, thread-safe mechanism to load balance the creation and processing of work items in our application. Part of the IProducer(Of T) interface is: 1: Public Interface IProducer(Of T) 2: Event ItemProduced(ByVal sender As IProducer(Of T), ByVal item As T) 3: Event ProductionComplete(ByVal sender As IProducer(Of T)) 4: End Interface Nothing sinister there, is there? In order to simplify our developers’ lives, I wrapped the queue with some functionality to manage the produces and consumers. Since the developer can specify the number of producers and consumers that are spun up, the queue code manages adding event handlers as the producers and consumers are instantiated. Now, we’ve been having some memory leaks and, in order to eliminate the possibility that this was caused by weak references to event handles, I wanted to remove them. This is where it got dicey. My first attempt looked like this: 1: For Each producer As P In Producers 2: RemoveHandler producer.ItemProduced, AddressOf ItemProducedHandler 3: RemoveHandler producer.ProductionComplete, AddressOf ProductionCompleteHandler 4: producer.Dispose() 5: Next What you can’t see in my posted code are the warnings this caused. The 'AddressOf' expression has no effect in this context because the method argument to 'AddressOf' requires a relaxed conversion to the delegate type of the event. Assign the 'AddressOf' expression to a variable, and use the variable to add or remove the method as the handler.  Now, what on earth does that mean? Well, a quick Bing search uncovered a whole bunch of talk about delegates. The first solution I found just changed all parameters in the event handler to Object. Sorry, but no. I used generics precisely because I wanted type safety, not because I wanted to use Object. More searching. Eventually, I found this forum post, where Jeff Shan revealed a missing piece of the puzzle. The other revelation came from Lian_ZA in this post. However, these two only hinted at the solution. Trying some of what they suggested led to finally getting an invalid cast exception that revealed the existence of ItemProducedEventHandler. Hold on a minute! I didn’t create that delegate. There’s nothing even close to that name in my code… except the ItemProduced event in the interface. Could it be? Naaaaah. Hmmm…. Well, as it turns out, there is a delegate created by the compiler for each event. By explicitly creating a delegate that refers to the method in question, implicitly cast to the generated delegate type, I was able to remove the handlers: 1: For Each producer As P In Producers 2: Dim _itemProducedHandler As IProducer(Of T).ItemProducedEventHandler = AddressOf ItemProducedHandler 3: RemoveHandler producer.ItemProduced, _itemProducedHandler 4:  5: Dim _productionCompleteHandler As IProducer(Of T).ProductionCompleteEventHandler = AddressOf ProductionCompleteHandler 6: RemoveHandler producer.ProductionComplete, _productionCompleteHandler 7: producer.Dispose() 8: Next That’s “all” it took to finally be able to remove the event handlers and maintain type-safe code. Hopefully, this will save you the same challenges I had in trying to figure out how to fix this issue!

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• Any tips on getting hired as a software project manager straight out of college?

  - by MHarrison

  I graduated with a BS in compsci last September, and I've been trying (unsuccessfully) to find a job as a project manager ever since. I fell in love with software engineering (the formal practice behind it all, not just coding) in school, and I've dedicated the last 3-4 years of my life to learning everything I can about project management and gaining experience. I've managed several projects (with teams around 12 people) while in school, and I worked with my university's software engineering research lab. My résumé is also decent - I worked as a programmer before I went to school (I'm 27 now), and I did Google Summer of Code for 3 summers. I also have general "people management" experience via working as the photo editor for my university's newspaper for 2 years. My first problem with the job hunt is not getting enough interviews. I use careers.stackoverflow.com, which is awesome because I usually get contacted by non-HR people who know what they're talking about, but there's just not enough companies using it for me to get interviews on a regular basis. I've also tried sites like monster.com, and in a fit of desperation, I sent out no less than 60 applications to project management positions. I've gotten 3 automated rejection letters and that's it. At least careers.stackoverflow gets me a phone interview with 8/10 places I apply to. But the main (and extremely frustrating) problem is the matter of experience. I've successfully managed projects from start to finish (in my software engineering classes we had real customers come in with a real software need and we built it for them), but I've never had to deal with budgets and money (I know this is why HR people immediately turn me away). Most of these positions require 5+ years PM experience, and I've seen absurd things like 12+ years required. Interviews are also maddening. I've had so many places who absolutely loved me and I made it to the final round of interviews, and I left thinking things went extremely well and they'd consider me. However, when I check in with them a week later, they tell me "We really liked you and your qualifications are excellent, but we're hoping to find someone with more experience." The bad interviews I can understand - like the PM position that would have had me managing developers both locally and overseas - I had 3 interviews with them and the ENTIRE interview process was them asking me CS brainteasers and having me waste time on things like writing quicksort on paper or writing binary search trees. Even when I tried steering the discussion towards more relevant PM stuff, they gave me some vague generic replies and went back to the "We want to be Google/MS" crap. But when I have a GOOD interview, they say my "qualifications are excellent" but they want "more experience"...that makes me want to tear my hair out. What else can I DO? While I'm aiming for technically-involved PM positions (not just crunching budget numbers), I really don't want a straight development job because I like creating software from the very high-level vs. spending a lot of time debugging memory leaks. In fact, I can't even GET development positions that I'm qualified for because I make the mistake of telling them that my future career goals are as PM (which usually results in them saying something like "Well we already have PMs and this position isn't really set up to get you there." - which I take to mean "No, that's my job, stay away.") My apologies on the long rant, but I'm seriously hellbent on getting hired as a PM since it's both my career goal and the passion that keeps me awake at night. Any suggestions on what the heck else I can do? I'm currently writing a blog where I talk about my philosophies about software engineering, and I'm writing up specs for an iOS app which I will design, code, and show employers, but this takes an awful lot of time that I don't have.

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• Tuning Linux IP routing parameters -- secret_interval and tcp_mem

  - by Jeff Atwood

  We had a little failover problem with one of our HAProxy VMs today. When we dug into it, we found this: Jan 26 07:41:45 haproxy2 kernel: [226818.070059] __ratelimit: 10 callbacks suppressed Jan 26 07:41:45 haproxy2 kernel: [226818.070064] Out of socket memory Jan 26 07:41:47 haproxy2 kernel: [226819.560048] Out of socket memory Jan 26 07:41:49 haproxy2 kernel: [226822.030044] Out of socket memory Which, per this link, apparently has to do with low default settings for net.ipv4.tcp_mem. So we increased them by 4x from their defaults (this is Ubuntu Server, not sure if the Linux flavor matters): current values are: 45984 61312 91968 new values are: 183936 245248 367872 After that, we started seeing a bizarre error message: Jan 26 08:18:49 haproxy1 kernel: [ 2291.579726] Route hash chain too long! Jan 26 08:18:49 haproxy1 kernel: [ 2291.579732] Adjust your secret_interval! Shh.. it's a secret!! This apparently has to do with /proc/sys/net/ipv4/route/secret_interval which defaults to 600 and controls periodic flushing of the route cache The secret_interval instructs the kernel how often to blow away ALL route hash entries regardless of how new/old they are. In our environment this is generally bad. The CPU will be busy rebuilding thousands of entries per second every time the cache is cleared. However we set this to run once a day to keep memory leaks at bay (though we've never had one). While we are happy to reduce this, it seems odd to recommend dropping the entire route cache at regular intervals, rather than simply pushing old values out of the route cache faster. After some investigation, we found /proc/sys/net/ipv4/route/gc_elasticity which seems to be a better option for keeping the route table size in check: gc_elasticity can best be described as the average bucket depth the kernel will accept before it starts expiring route hash entries. This will help maintain the upper limit of active routes. We adjusted elasticity from 8 to 4, in the hopes of the route cache pruning itself more aggressively. The secret_interval does not feel correct to us. But there are a bunch of settings and it's unclear which are really the right way to go here. /proc/sys/net/ipv4/route/gc_elasticity (8) /proc/sys/net/ipv4/route/gc_interval (60) /proc/sys/net/ipv4/route/gc_min_interval (0) /proc/sys/net/ipv4/route/gc_timeout (300) /proc/sys/net/ipv4/route/secret_interval (600) /proc/sys/net/ipv4/route/gc_thresh (?) rhash_entries (kernel parameter, default unknown?) We don't want to make the Linux routing worse, so we're kind of afraid to mess with some of these settings. Can anyone advise which routing parameters are best to tune, for a high traffic HAProxy instance?

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• Using OpenVPN, yet netflix.com blocks access

  - by user837848

  I have set up an OpenVPN server on a VPS in the USA and configured it to route all clients traffic through it. Everything seems to work fine regarding the VPN connection in gerneral. All ip lookup sites show me the us server's ip address and even hulu.com works(it won't work if you are not in the usa). But for some reason netflix.com says "Sorry, Netflix is not available in your country yet.". So I thought that netflix probably uses some more sophisticated ways to determine your location beyond just your ip address. But I could not find a way to get it to work until I dropped the idea of using a VPN and instead connected to the server via a simple socks tunnel with ssh by running: ssh -D 9999 user@serverip All I had to do was changing the key network.proxy.socks_remote_dns in Firefox from false to true to prevent DNS leaks and setting up the socks proxy. Then I could finally watch netflix.com. As a result I concluded that there is nothing in the browser(or something like system timezone) that tells netflix the location, so it has to have something to do with the OpenVPN config. After that I used tcpdump to log all the traffic on the server's network interface venet0 (OpenVZ VPS), visited netflix.com on the client while first connected to the VPN and then connected via socks tunnel and afterwards compared both outputs. The only thing that caught my eye was that while using the socks tunnel the server mainly used ipv6 to connect to netflix whereas it only used ipv4 when the client was connected to the OpenVPN server. But I don't get how that could make such a difference. So what am I missing? Is there a way to configure OpenVPN to also use ipv6 to connect to a website although there is only an ipv4 connection between the VPS and the client? Here is the server.conf of the OpenVPN server (OpenVZ VPS) local serverip port 443 proto tcp dev tun ca ./easy-rsa2/keys/ca.crt cert ./easy-rsa2/keys/vps1.crt key ./easy-rsa2/keys/vps1.key # This file should be kept secret dh ./easy-rsa2/keys/dh1024.pem server 10.8.0.0 255.255.255.0 ifconfig-pool-persist ipp.txt push "redirect-gateway def1 bypass-dhcp" push "dhcp-option DNS 8.8.8.8" push "dhcp-option DNS 8.8.4.4" client-to-client keepalive 10 120 tls-auth ta.key 0 # This file is secret cipher AES-256-CBC comp-lzo max-clients 4 user nobody group nogroup persist-key persist-tun status openvpn-status.log log-append openvpn.log verb 3 iptables forwarding iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o venet0 -j SNAT --to-source serverip (enabled ipv4 forwarding) I have tried everything always on a Win7 and a Debian client with only ipv4 connections and always made sure that they use the correct DNS server (tested with ipleak.net and tcpdump / wireshark). client.conf: client dev tun proto tcp remote serverip 443 resolv-retry infinite nobind persist-key persist-tun ca ca.crt cert client.crt key client.key ns-cert-type server tls-auth ta.key 1 cipher AES-256-CBC comb-lzo verb 3

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• Using the Static Code Analysis feature of Visual Studio (Premium/Ultimate) to find memory leakage problems

  - by terje

  Memory for managed code is handled by the garbage collector, but if you use any kind of unmanaged code, like native resources of any kind, open files, streams and window handles, your application may leak memory if these are not properly handled.  To handle such resources the classes that own these in your application should implement the IDisposable interface, and preferably implement it according to the pattern described for that interface. When you suspect a memory leak, the immediate impulse would be to start up a memory profiler and start digging into that.   However, before you follow that impulse, do a Static Code Analysis run with a ruleset tuned to finding possible memory leaks in your code.  If you get any warnings from this, fix them before you go on with the profiling. How to use a ruleset In Visual Studio 2010 (Premium and Ultimate editions) you can define your own rulesets containing a list of Static Code Analysis checks.   I have defined the memory checks as shown in the lists below as ruleset files, which can be downloaded – see bottom of this post.  When you get them, you can easily attach them to every project in your solution using the Solution Properties dialog. Right click the solution, and choose Properties at the bottom, or use the Analyze menu and choose “Configure Code Analysis for Solution”: In this dialog you can now choose the Memorycheck ruleset for every project you want to investigate.  Pressing Apply or Ok opens every project file and changes the projects code analysis ruleset to the one we have specified here. How to define your own ruleset  (skip this if you just download my predefined rulesets) If you want to define the ruleset yourself, open the properties on any project, choose Code Analysis tab near the bottom, choose any ruleset in the drop box and press Open Clear out all the rules by selecting “Source Rule Sets” in the Group By box, and unselect the box Change the Group By box to ID, and select the checks you want to include from the lists below. Note that you can change the action for each check to either warning, error or none, none being the same as unchecking the check.   Now go to the properties window and set a new name and description for your ruleset. Then save (File/Save as) the ruleset using the new name as its name, and use it for your projects as detailed above. It can also be wise to add the ruleset to your solution as a solution item. That way it’s there if you want to enable Code Analysis in some of your TFS builds.   Running the code analysis In Visual Studio 2010 you can either do your code analysis project by project using the context menu in the solution explorer and choose “Run Code Analysis”, you can define a new solution configuration, call it for example Debug (Code Analysis), in for each project here enable the Enable Code Analysis on Build   In Visual Studio Dev-11 it is all much simpler, just go to the Solution root in the Solution explorer, right click and choose “Run code analysis on solution”.     The ruleset checks The following list is the essential and critical memory checks.  CheckID Message Can be ignored ? Link to description with fix suggestions CA1001 Types that own disposable fields should be disposable No  http://msdn.microsoft.com/en-us/library/ms182172.aspx CA1049 Types that own native resources should be disposable Only if the pointers assumed to point to unmanaged resources point to something else  http://msdn.microsoft.com/en-us/library/ms182173.aspx CA1063 Implement IDisposable correctly No  http://msdn.microsoft.com/en-us/library/ms244737.aspx CA2000 Dispose objects before losing scope No  http://msdn.microsoft.com/en-us/library/ms182289.aspx CA2115 1 Call GC.KeepAlive when using native resources See description  http://msdn.microsoft.com/en-us/library/ms182300.aspx CA2213 Disposable fields should be disposed If you are not responsible for release, of if Dispose occurs at deeper level  http://msdn.microsoft.com/en-us/library/ms182328.aspx CA2215 Dispose methods should call base class dispose Only if call to base happens at deeper calling level  http://msdn.microsoft.com/en-us/library/ms182330.aspx CA2216 Disposable types should declare a finalizer Only if type does not implement IDisposable for the purpose of releasing unmanaged resources  http://msdn.microsoft.com/en-us/library/ms182329.aspx CA2220 Finalizers should call base class finalizers No  http://msdn.microsoft.com/en-us/library/ms182341.aspx Notes: 1) Does not result in memory leak, but may cause the application to crash   The list below is a set of optional checks that may be enabled for your ruleset, because the issues these points too often happen as a result of attempting to fix up the warnings from the first set.   ID Message Type of fault Can be ignored ? Link to description with fix suggestions CA1060 Move P/invokes to NativeMethods class Security No http://msdn.microsoft.com/en-us/library/ms182161.aspx CA1816 Call GC.SuppressFinalize correctly Performance Sometimes, see description http://msdn.microsoft.com/en-us/library/ms182269.aspx CA1821 Remove empty finalizers Performance No http://msdn.microsoft.com/en-us/library/bb264476.aspx CA2004 Remove calls to GC.KeepAlive Performance and maintainability Only if not technically correct to convert to SafeHandle http://msdn.microsoft.com/en-us/library/ms182293.aspx CA2006 Use SafeHandle to encapsulate native resources Security No http://msdn.microsoft.com/en-us/library/ms182294.aspx CA2202 Do not dispose of objects multiple times Exception (System.ObjectDisposedException) No http://msdn.microsoft.com/en-us/library/ms182334.aspx CA2205 Use managed equivalents of Win32 API Maintainability and complexity Only if the replace doesn’t provide needed functionality http://msdn.microsoft.com/en-us/library/ms182365.aspx CA2221 Finalizers should be protected Incorrect implementation, only possible in MSIL coding No http://msdn.microsoft.com/en-us/library/ms182340.aspx   Downloadable ruleset definitions I have defined three rulesets, one called Inmeta.Memorycheck with the rules in the first list above, and Inmeta.Memorycheck.Optionals containing the rules in the second list, and the last one called Inmeta.Memorycheck.All containing the sum of the two first ones.  All three rulesets can be found in the  zip archive  “Inmeta.Memorycheck” downloadable from here.   Links to some other resources relevant to Static Code Analysis MSDN Magazine Article by Mickey Gousset on Static Code Analysis in VS2010 MSDN :  Analyzing Managed Code Quality by Using Code Analysis, root of the documentation for this Preventing generated code from being analyzed using attributes Online training course on Using Code Analysis with VS2010 Blogpost by Tatham Oddie on custom code analysis rules How to write custom rules, from Microsoft Code Analysis Team Blog Microsoft Code Analysis Team Blog

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• Android "Trying to use recycled bitmap" error?

  - by Mike

  Hi all, I am running into a problem with bitmaps on an Android application I am working on. What is suppose to happen is that the application downloads images from a website, saves them to the device, loads them into memory as bitmaps into an arraylist, and displays them to the user. This all works fine when the application is first started. However, I have added a refresh option for the user where the images are deleted, and the process outlined above starts all over. My problem: By using the refresh option the old images were still in memory and I would quickly get OutOfMemoryErrors. Thus, if the images are being refreshed, I had it run through the arraylist and recycle the old images. However, when the application goes to load the new images into the arraylist, it crashes with a "Trying to use recycled bitmap" error. As far as I understand it, recycling a bitmap destroys the bitmap and frees up its memory for other objects. If I want to use the bitmap again, it has to be reinitialized. I believe that I am doing this when the new files are loaded into the arraylist, but something is still wrong. Any help is greatly appreciated as this is very frustrating. The problem code is below. Thank you! public void fillUI(final int refresh) { // Recycle the images to avoid memory leaks if(refresh==1) { for(int x=0; x<images.size(); x++) images.get(x).recycle(); images.clear(); selImage=-1; // Reset the selected image variable } final ProgressDialog progressDialog = ProgressDialog.show(this, null, this.getString(R.string.loadingImages)); // Create the array with the image bitmaps in it new Thread(new Runnable() { public void run() { Looper.prepare(); File[] fileList = new File("/data/data/[package name]/files/").listFiles(); if(fileList!=null) { for(int x=0; x<fileList.length; x++) { try { images.add(BitmapFactory.decodeFile("/data/data/[package name]/files/" + fileList[x].getName())); } catch (OutOfMemoryError ome) { Log.i(LOG_FILE, "out of memory again :("); } } Collections.reverse(images); } fillUiHandler.sendEmptyMessage(0); } }).start(); fillUiHandler = new Handler() { public void handleMessage(Message msg) { progressDialog.dismiss(); } }; }

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• Session Id in url and/or cookie? [closed]

  - by Jacco

  Most people advice against rewriting every (internal) url to include the sessionId (both GET and POST). The standard argument against it seems to be:   If an attacker gets hold of the sessionId, they can hijack the session.   With the sessionId in the url, it easily leaks to the attacker (by referer etc.) But what if you put the sessionId in both an (encrypted) cookie and the url. if the sessionId in either the cookie or the url is missing or if they do not match, decline the request. Let's pretend the website in question is free of xss holes, the cookie encryption is strong enough, etc. etc. Then what is the increased risk of rewriting every url to include the sessionId? UPDATE: @Casper That is a very good point. so up to now there are 2 reasons: bad for search engines / SEO if used in public part of the website can cause trouble when users post an url with a session Id on a forum, send it trough email or bookmark the page apart from the:   It increases the security risk, but it is not clear what the increased risk is. some background info: I've a website that offers blog-like service to travellers. I cannot be sure cookies work nor can I require cookies to work. Most computers in internet cafes are old and not (even close to) up-to-date. The user has no control over them and the connection can be very unreliable for some more 'off the beaten path' locations. Binding the session to an IP-address is not possible, some places use load-balancing proxies with multiple IP addresses. (and from China there is The Great Firewall). Upon receiving the first cookie back, I flag cookies as mandatory. However, if the cookie was flagged as mandatory but not there, I ask for their password once more, knowing their session from the url. (Also cookies have a 1 time token in them, but that's not the point of this question). UPDATE 2: The conclusion seems to be that there are no extra *security* issues when you expose you session id trough the URL while also keeping a copy of the session id in an encrypted cookie. Do not hesitate to add additional information about any possible security implications

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• Android AsyncTask context problem, help!

  - by dnkoutso

  I've been working with AsyncTasks in Android and I am dealing with a strange issue. Take a simple example, an Activity with one AsyncTask. The task on the background does not do anything spectacular, it just sleeps for 8 seconds. At the end of the AsyncTask in the onPostExecute() method I am just setting a button visibility status to View.VISIBLE, only to verify my results. Now, this works great until the user decides to change his phones orientation while the AsyncTask is working (within the 8 second sleep window). I understand the Android activity life cycle and I know the activity gets destroyed and recreated. This is where the problem comes in. The AsyncTask is referring to a button and apparently holds a reference to the context that started the AsyncTask in the first place. I would expect, that this old context (since the user caused an orientation change) to either become null and the AsyncTask to throw an NPE for the reference to the button it is trying to make visible. Instead, no NPE is thrown, the asynctask thinks that the button reference is not null, sets it to visible. The result? Nothing is happening on the screen! I have tackled this by keeping and updating the context reference into the AsyncTask. This is cumbersome and prone to leaks. Here's the code: public class Main extends Activity { private Button mButton = null; private Button mTestButton = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mButton = (Button) findViewById(R.id.btnStart); mButton.setOnClickListener(new OnClickListener () { @Override public void onClick(View v) { new taskDoSomething().execute(0l); } }); mTestButton = (Button) findViewById(R.id.btnTest); } private class taskDoSomething extends AsyncTask<Long, Integer, Integer> { @Override protected Integer doInBackground(Long... params) { Log.i("LOGGER", "Starting..."); try { Thread.sleep(8000); } catch (InterruptedException e) { e.printStackTrace(); } return 0; } @Override protected void onPostExecute(Integer result) { Log.i("LOGGER", "...Done"); mTestButton.setVisibility(View.VISIBLE); } } } Try executing and while the AsyncTask is working change your phones orientation.

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