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• Qt : crash due to delete (trying to handle exceptions...)

  - by Seub

  I am writing a program with Qt, and I would like it to show a dialog box with a Exit | Restart choice whenever an error is thrown somewhere in the code. What I did causes a crash and I really can't figure out why it happens, I was hoping you could help me understanding what's going on. Here's my main.cpp: #include "my_application.hpp" int main(int argc, char *argv[]) { std::cout << std::endl; My_Application app(argc, argv); return app.exec(); } And here's my_application:hpp: #ifndef MY_APPLICATION_HPP #define MY_APPLICATION_HPP #include <QApplication> class Window; class My_Application : public QApplication { public: My_Application(int& argc, char ** argv); virtual ~My_Application(); virtual bool notify(QObject * receiver, QEvent * event); private: Window *window_; void exit(); void restart(); }; #endif // MY_APPLICATION_HPP Finally, here's my_application.cpp: #include "my_application.hpp" #include "window.hpp" #include <QMessageBox> My_Application::My_Application(int& argc, char ** argv) : QApplication(argc, argv) { window_ = new Window; window_->setAttribute(Qt::WA_DeleteOnClose, false); window_->show(); } My_Application::~My_Application() { delete window_; } bool My_Application::notify(QObject * receiver, QEvent * event) { try { return QApplication::notify(receiver, event); } catch(QString error_message) { window_->setEnabled(false); QMessageBox message_box; message_box.setWindowTitle("Error"); message_box.setIcon(QMessageBox::Critical); message_box.setText("The program caught an unexpected error:"); message_box.setInformativeText("What do you want to do? <br>"); QPushButton *restart_button = message_box.addButton(tr("Restart"), QMessageBox::RejectRole); QPushButton *exit_button = message_box.addButton(tr("Exit"), QMessageBox::RejectRole); message_box.setDefaultButton(restart_button); message_box.exec(); if ((QPushButton *) message_box.clickedButton() == exit_button) { exit(); } else if ((QPushButton *) message_box.clickedButton() == restart_button) { restart(); } } return false; } void My_Application::exit() { window_->close(); //delete window_; return; } void My_Application::restart() { window_->close(); //delete window_; window_ = new Window; window_->show(); return; } Note that the line window_->setAttribute(Qt::WA_DeleteOnClose, false); means that window_ (my main window) won't be deleted when it is closed. The code I've written above works, but as far as I understand, there's a memory leak: I should uncomment the line //delete window_; in My_Application::exit() and My_Application::restart(). But when I do that, the program crashes when I click restart (or exit but who cares). (I'm not sure this is useful, in fact it might be misleading, but here's what my debugger tells me: a segmentation fault occurs in QWidgetPrivate::PaintOnScreen() const which is called by a function called by a function... called by My_Application::notify()) When I do some std::couts, I notice that the program runs through the entire restart() function and in fact through the entire notify() function before it crashes. I have no idea why it crashes. Thanks in advance for your insights! Update: I've noticed that My_Application::notify() is called very often. For example, it is called a bunch of times while the error dialog box is open, also during the execution of the restart function. The crash actually occurs in the subfunction QApplication::notify(receiver, event). This is not too surprising in light of the previous remark (the receiver has probably been deleted) But even if I forbid the function My_Application::notify() to do anything while restart() is executed, it still crashes (after having called My_Application::notify() a bunch of times, like 15 times, isn't that weird)? How should I proceed? Maybe I should say (to make the question slightly more relevant) that my class My_Application also has a "restore" function, which I've not copied here to try to keep things short. If I just had that restart feature I wouldn't bother too much, but I do want to have that restore feature. I should also say that if I keep the code with the "delete window_" commented, the problem is not only a memory leak, it still crashes sometimes apparently. There must surely be a way to fix this! But I'm clueless, I'd really appreciate some help! Thanks in advance.

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• DOMDocument::load in PHP 5

  - by Abs

  Hello all, I open a 10MB+ XML file several times in my script in different functions: $dom = DOMDocument::load( $file ) or die('couldnt open'); 1) Is the above the old style of loading a document? I am using PHP 5. Oppening it statically? 2) Do I need to close the loading of the XML file, if possible? I suspect its causing memory problems because I loop through the nodes of the XML file several thousand times and sometimes my script just ends abruptly. Thanks all for any help

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• Windows Azure: General Availability of Web Sites + Mobile Services, New AutoScale + Alerts Support, No Credit Card Needed for MSDN

  - by ScottGu

  This morning we released a major set of updates to Windows Azure.  These updates included: Web Sites: General Availability Release of Windows Azure Web Sites with SLA Mobile Services: General Availability Release of Windows Azure Mobile Services with SLA Auto-Scale: New automatic scaling support for Web Sites, Cloud Services and Virtual Machines Alerts/Notifications: New email alerting support for all Compute Services (Web Sites, Mobile Services, Cloud Services, and Virtual Machines) MSDN: No more credit card requirement for sign-up All of these improvements are now available to use immediately (note: some are still in preview).  Below are more details about them. Web Sites: General Availability Release of Windows Azure Web Sites I’m incredibly excited to announce the General Availability release of Windows Azure Web Sites. The Windows Azure Web Sites service is perfect for hosting a web presence, building customer engagement solutions, and delivering business web apps.  Today’s General Availability release means we are taking off the “preview” tag from the Free and Standard (formerly called reserved) tiers of Windows Azure Web Sites.  This means we are providing: A 99.9% monthly SLA (Service Level Agreement) for the Standard tier Microsoft Support available on a 24x7 basis (with plans that range from developer plans to enterprise Premier support) The Free tier runs in a shared compute environment and supports up to 10 web sites. While the Free tier does not come with an SLA, it works great for rapid development and testing and enables you to quickly spike out ideas at no cost. The Standard tier, which was called “Reserved” during the preview, runs using dedicated per-customer VM instances for great performance, isolation and scalability, and enables you to host up to 500 different Web sites within them.  You can easily scale your Standard instances on-demand using the Windows Azure Management Portal.  You can adjust VM instance sizes from a Small instance size (1 core, 1.75GB of RAM), up to a Medium instance size (2 core, 3.5GB of RAM), or Large instance (4 cores and 7 GB RAM).  You can choose to run between 1 and 10 Standard instances, enabling you to easily scale up your web backend to 40 cores of CPU and 70GB of RAM: Today’s release also includes general availability support for custom domain SSL certificate bindings for web sites running using the Standard tier. Customers will be able to utilize certificates they purchase for their custom domains and use either SNI or IP based SSL encryption. SNI encryption is available for all modern browsers and does not require an IP address.  SSL certificates can be used for individual sites or wild-card mapped across multiple sites (we charge extra for the use of a SSL cert – but the fee is per-cert and not per site which means you pay once for it regardless of how many sites you use it with).  Today’s release also includes the following new features: Auto-Scale support Today’s Windows Azure release adds preview support for Auto-Scaling web sites.  This enables you to setup automatic scale rules based on the activity of your instances – allowing you to automatically scale down (and save money) when they are below a CPU threshold you define, and automatically scale up quickly when traffic increases.  See below for more details. 64-bit and 32-bit mode support You can now choose to run your standard tier instances in either 32-bit or 64-bit mode (previously they only ran in 32-bit mode).  This enables you to address even more memory within individual web applications. Memory dumps Memory dumps can be very useful for diagnosing issues and debugging apps. Using a REST API, you can now get a memory dump of your sites, which you can then use for investigating issues in Visual Studio Debugger, WinDbg, and other tools. Scaling Sites Independently Prior to today’s release, all sites scaled up/down together whenever you scaled any site in a sub-region. So you may have had to keep your proof-of-concept or testing sites in a separate sub-region if you wanted to keep them in the Free tier. This will no longer be necessary.  Windows Azure Web Sites can now mix different tier levels in the same geographic sub-region. This allows you, for example, to selectively move some of your sites in the West US sub-region up to Standard tier when they require the features, scalability, and SLA of the Standard tier. Full pricing details on Windows Azure Web Sites can be found here.  Note that the “Shared Tier” of Windows Azure Web Sites remains in preview mode (and continues to have discounted preview pricing).  Mobile Services: General Availability Release of Windows Azure Mobile Services I’m incredibly excited to announce the General Availability release of Windows Azure Mobile Services.  Mobile Services is perfect for building scalable cloud back-ends for Windows 8.x, Windows Phone, Apple iOS, Android, and HTML/JavaScript applications.  Customers We’ve seen tremendous adoption of Windows Azure Mobile Services since we first previewed it last September, and more than 20,000 customers are now running mobile back-ends in production using it.  These customers range from startups like Yatterbox, to university students using Mobile Services to complete apps like Sly Fox in their spare time, to media giants like Verdens Gang finding new ways to deliver content, and telcos like TalkTalk Business delivering the up-to-the-minute information their customers require.  In today’s Build keynote, we demonstrated how TalkTalk Business is using Windows Azure Mobile Services to deliver service, outage and billing information to its customers, wherever they might be. Partners When we unveiled the source control and Custom API features I blogged about two weeks ago, we enabled a range of new scenarios, one of which is a more flexible way to work with third party services.  The following blogs, samples and tutorials from our partners cover great ways you can extend Mobile Services to help you build rich modern apps: New Relic allows developers to monitor and manage the end-to-end performance of iOS and Android applications connected to Mobile Services. SendGrid eliminates the complexity of sending email from Mobile Services, saving time and money, while providing reliable delivery to the inbox. Twilio provides a telephony infrastructure web service in the cloud that you can use with Mobile Services to integrate phone calls, text messages and IP voice communications into your mobile apps. Xamarin provides a Mobile Services add on to make it easy building cross-platform connected mobile aps. Pusher allows quickly and securely add scalable real-time messaging functionality to Mobile Services-based web and mobile apps. Visual Studio 2013 and Windows 8.1 This week during //build/ keynote, we demonstrated how Visual Studio 2013, Mobile Services and Windows 8.1 make building connected apps easier than ever. Developers building Windows 8 applications in Visual Studio can now connect them to Windows Azure Mobile Services by simply right clicking then choosing Add Connected Service. You can either create a new Mobile Service or choose existing Mobile Service in the Add Connected Service dialog. Once completed, Visual Studio adds a reference to Mobile Services SDK to your project and generates a Mobile Services client initialization snippet automatically. Add Push Notifications Push Notifications and Live Tiles are a key to building engaging experiences. Visual Studio 2013 and Mobile Services make it super easy to add push notifications to your Windows 8.1 app, by clicking Add a Push Notification item: The Add Push Notification wizard will then guide you through the registration with the Windows Store as well as connecting your app to a new or existing mobile service. Upon completion of the wizard, Visual Studio will configure your mobile service with the WNS credentials, as well as add sample logic to your client project and your mobile service that demonstrates how to send push notifications to your app. Server Explorer Integration In Visual Studio 2013 you can also now view your Mobile Services in the the Server Explorer. You can add tables, edit, and save server side scripts without ever leaving Visual Studio, as shown on the image below: Pricing With today’s general availability release we are announcing that we will be offering Mobile Services in three tiers – Free, Standard, and Premium.  Each tier is metered using a simple pricing model based on the # of API calls (bandwidth is included at no extra charge), and the Standard and Premium tiers are backed by 99.9% monthly SLAs.  You can elastically scale up or down the number of instances you have of each tier to increase the # of API requests your service can support – allowing you to efficiently scale as your business grows. The following table summarizes the new pricing model (full pricing details here):   You can find the full details of the new pricing model here. Build Conference Talks The //BUILD/ conference will be packed with sessions covering every aspect of developing connected applications with Mobile Services. The best part is that, even if you can’t be with us in San Francisco, every session is being streamed live. Be sure not to miss these talks: Mobile Services – Soup to Nuts — Josh Twist Building Cross-Platform Apps with Windows Azure Mobile Services — Chris Risner Connected Windows Phone Apps made Easy with Mobile Services — Yavor Georgiev Build Connected Windows 8.1 Apps with Mobile Services — Nick Harris Who’s that user? Identity in Mobile Apps — Dinesh Kulkarni Building REST Services with JavaScript — Nathan Totten Going Live and Beyond with Windows Azure Mobile Services — Kirill Gavrylyuk , Paul Batum Protips for Windows Azure Mobile Services — Chris Risner AutoScale: Dynamically scale up/down your app based on real-world usage One of the key benefits of Windows Azure is that you can dynamically scale your application in response to changing demand. In the past, though, you have had to either manually change the scale of your application, or use additional tooling (such as WASABi or MetricsHub) to automatically scale your application. Today, we’re announcing that AutoScale will be built-into Windows Azure directly.  With today’s release it is now enabled for Cloud Services, Virtual Machines and Web Sites (Mobile Services support will come soon). Auto-scale enables you to configure Windows Azure to automatically scale your application dynamically on your behalf (without any manual intervention) so you can achieve the ideal performance and cost balance. Once configured it will regularly adjust the number of instances running in response to the load in your application. Currently, we support two different load metrics: CPU percentage Storage queue depth (Cloud Services and Virtual Machines only) We’ll enable automatic scaling on even more scale metrics in future updates. When to use Auto-Scale The following are good criteria for services/apps that will benefit from the use of auto-scale: The service/app can scale horizontally (e.g. it can be duplicated to multiple instances) The service/app load changes over time If your app meets these criteria, then you should look to leverage auto-scale. How to Enable Auto-Scale To enable auto-scale, simply navigate to the Scale tab in the Windows Azure Management Portal for the app/service you wish to enable.  Within the scale tab turn the Auto-Scale setting on to either CPU or Queue (for Cloud Services and VMs) to enable Auto-Scale.  Then change the instance count and target CPU settings to configure the Auto-Scale ranges you want to maintain. The image below demonstrates how to enable Auto-Scale on a Windows Azure Web-Site.  I’ve configured the web-site so that it will run using between 1 and 5 VM instances.  The exact # used will depend on the aggregate CPU of the VMs using the 40-70% range I’ve configured below.  If the aggregate CPU goes above 70%, then Windows Azure will automatically add new VMs to the pool (up to the maximum of 5 instances I’ve configured it to use).  If the aggregate CPU drops below 40% then Windows Azure will automatically start shutting down VMs to save me money: Once you’ve turned auto-scale on, you can return to the Scale tab at any point and select Off to manually set the number of instances. Using the Auto-Scale Preview With today’s update you can now, in just a few minutes, have Windows Azure automatically adjust the number of instances you have running  in your apps to keep your service performant at an even better cost. Auto-scale is being released today as a preview feature, and will be free until General Availability. During preview, each subscription is limited to 10 separate auto-scale rules across all of the resources they have (Web sites, Cloud services or Virtual Machines). If you hit the 10 limit, you can disable auto-scale for any resource to enable it for another. Alerts and Notifications Starting today we are now providing the ability to configure threshold based alerts on monitoring metrics. This feature is available for compute services (cloud services, VM, websites and mobiles services). Alerts provide you the ability to get proactively notified of active or impending issues within your application.  You can define alert rules for: Virtual machine monitoring metrics that are collected from the host operating system (CPU percentage, network in/out, disk read bytes/sec and disk write bytes/sec) and on monitoring metrics from monitoring web endpoint urls (response time and uptime) that you have configured. Cloud service monitoring metrics that are collected from the host operating system (same as VM), monitoring metrics from the guest VM (from performance counters within the VM) and on monitoring metrics from monitoring web endpoint urls (response time and uptime) that you have configured. For Web Sites and Mobile Services, alerting rules can be configured on monitoring metrics from monitoring endpoint urls (response time and uptime) that you have configured. Creating Alert Rules You can add an alert rule for a monitoring metric by navigating to the Setting -> Alerts tab in the Windows Azure Management Portal. Click on the Add Rule button to create an alert rule. Give the alert rule a name and optionally add a description. Then pick the service which you want to define the alert rule on: The next step in the alert creation wizard will then filter the monitoring metrics based on the service you selected:   Once created the rule will show up in your alerts list within the settings tab: The rule above is defined as “not activated” since it hasn’t tripped over the CPU threshold we set.  If the CPU on the above machine goes over the limit, though, I’ll get an email notifying me from an Windows Azure Alerts email address ([email protected]). And when I log into the portal and revisit the alerts tab I’ll see it highlighted in red.  Clicking it will then enable me to see what is causing it to fail, as well as view the history of when it has happened in the past. Alert Notifications With today’s initial preview you can now easily create alerting rules based on monitoring metrics and get notified on active or impending issues within your application that require attention. During preview, each subscription is limited to 10 alert rules across all of the services that support alert rules. No More Credit Card Requirement for MSDN Subscribers Earlier this month (during TechEd 2013), Windows Azure announced that MSDN users will get Windows Azure Credits every month that they can use for any Windows Azure services they want. You can read details about this in my previous Dev/Test blog post. Today we are making further updates to enable an easier Windows Azure signup for MSDN users. MSDN users will now not be required to provide payment information (e.g. no credit card) during sign-up, so long as they use the service within the included monetary credit for the billing period. For usage beyond the monetary credit, they can enable overages by providing the payment information and remove the spending limit. This enables a super easy, one page sign-up experience for MSDN users.  Simply sign-up for your Windows Azure trial using the same Microsoft ID that you use to manage your MSDN account, then complete the one page sign-up form below and you will be able to spend your free monthly MSDN credits (up to $150 each month) on any Windows Azure resource for dev/test:   This makes it trivially easy for every MDSN customer to start using Windows Azure today.  If you haven’t signed up yet, I definitely recommend checking it out. Summary Today’s release includes a ton of great features that enable you to build even better cloud solutions.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using all of the above features today.  Then visit the Windows Azure Developer Center to learn more about how to build apps with it. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• How good is the memory mapped Circular Buffer on Wikipedia?

  - by abroun

  I'm trying to implement a circular buffer in C, and have come across this example on Wikipedia. It looks as if it would provide a really nice interface for anyone reading from the buffer, as reads which wrap around from the end to the beginning of the buffer are handled automatically. So all reads are contiguous. However, I'm a bit unsure about using it straight away as I don't really have much experience with memory mapping or virtual memory and I'm not sure that I fully understand what it's doing. What I think I understand is that it's mapping a shared memory file the size of the buffer into memory twice. Then, whenever data is written into the buffer it appears in memory in 2 places at once. This allows all reads to be contiguous. What would be really great is if someone with more experience of POSIX memory mapping could have a quick look at the code and tell me if the underlying mechanism used is really that efficient. Am I right in thinking for example that the file in /dev/shm used for the shared memory always stays in RAM or could it get written to the hard drive (performance hit) at some point? Are there any gotchas I should be aware of? As it stands, I'm probably going to use a simpler method for my current project, but it'd be good to understand this to have it in my toolbox for the future. Thanks in advance for your time.

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• What does the Kernel Virtual Memory of each process contain?

  - by claws

  When say 3 programs (executables) are loaded into memory the layout might look something like this: I've following questions: Is the concept of Virtual Memory limited to user processes? Because, I am wondering where does the Operating System Kernel, Drivers live? How is its memory layout? I know its operating system specific make your choice (windows/linux). They say, on a 32 bit machine in a 4GB address space. Half of it (or more recently 1GB) is occupied by kernel. I can see in this diagram that "Kernel Virtual memory" is occupying 0xc0000000 - 0xffffffff (= 1 GB). Are they talking about this? or is it something else? Just want to confirm. What exactly does the Kernel Virtual Memory of each of these processes contain? What is its layout? When we do IPC we talk about shared memory. I don't see any memory shared between these processes. Where does it live? Resources (files, registries in windows) are global to all processes. So, the resource/file handle table must be in some global space. Which area would that be in? Where can I know more about this kernel side stuff.

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• AIX Checklist for stable obiee deployment

  - by user554629

  Common AIX configuration issues     ( last updated 27 Aug 2012 ) OBIEE is a complicated system with many moving parts and connection points.The purpose of this article is to provide a checklist to discuss OBIEE deployment with your systems administrators. The information in this article is time sensitive, and updated as I discover new  issues or details. What makes OBIEE different? When Tech Support suggests AIX component upgrades to a stable, locked-down production AIX environment, it is common to get "push back".  "Why is this necessary?  We aren't we seeing issues with other software?"It's a fair question that I have often struggled to answer; here are the talking points: OBIEE is memory intensive.  It is the entire purpose of the software to trade memory for repetitive, more expensive database requests across a network. OBIEE is implemented in C++ and is very dependent on the C++ runtime to behave correctly. OBIEE is aggressively thread efficient;  if atomic operations on a particular architecture do not work correctly, the software crashes. OBIEE dynamically loads third-party database client libraries directly into the nqsserver process.  If the library is not thread-safe, or corrupts process memory the OBIEE crash happens in an unrelated part of the code.  These are extremely difficult bugs to find. OBIEE software uses 99% common source across multiple platforms:  Windows, Linux, AIX, Solaris and HPUX.  If a crash happens on only one platform, we begin to suspect other factors.  load intensity, system differences, configuration choices, hardware failures.  It is rare to have a single product require so many diverse technical skills.   My role in support is to understand system configurations, performance issues, and crashes.   An analyst trained in Business Analytics can't be expected to know AIX internals in the depth required to make configuration choices.  Here are some guidelines. AIX C++ Runtime must be at  version 11.1.0.4$ lslpp -L | grep xlC.aixobiee software will crash if xlC.aix.rte is downlevel;  this is not a "try it" suggestion.Nov 2011 11.1.0.4 version  is appropriate for all AIX versions ( 5, 6, 7 )Download from here:https://www-304.ibm.com/support/docview.wss?uid=swg24031426 No reboot is necessary to install, it can even be installed while applications are using the current version.Restart the apps, and they will pick up the latest version. AIX 5.3 Technology Level 12 is required when running on Power5,6,7 processorsAIX 6.1 was introduced with the newer Power chips, and we have seen no issues with 6.1 or 7.1 versions.Customers with an unstable deployment, dozens of unexplained crashes, became stable after the upgrade.If your AIX system is 5.3, the minimum TL level should be at or higher than this:$ oslevel -s  5300-12-03-1107IBM typically supports only the two latest versions of AIX ( 6.1 and 7.1, for example).  AIX 5.3 is still supported and popular running in an LPAR. obiee userid limits$ ulimit -Ha  ( hard limits )$ ulimit -a   ( default limits )core file size (blocks)     unlimiteddata seg size (kbytes)      unlimitedfile size (blocks)          unlimitedmax memory size (kbytes)    unlimitedopen files                  10240 cpu time (seconds)          unlimitedvirtual memory (kbytes)     unlimitedIt is best to establish the values in /etc/security/limitsroot user is needed to observe and modify this file.If you modify a limit, you will need to relog in to change it again.  For example,$ ulimit -c 0$ ulimit -c 2097151cannot modify limit: Operation not permitted$ ulimit -c unlimited$ ulimit -c0There are only two meaningful values for ulimit -c ; zero or unlimited.Anything else is likely to produce a truncated core file that cannot be analyzed. Deploy 32-bit or 64-bit ?Early versions of OBIEE offered 32-bit or 64-bit choice to AIX customers.The 32-bit choice was needed if a database vendor did not supply a 64-bit client library.That's no longer an issue and beginning with OBIEE 11, 32-bit code is no longer shipped.A common error that leads to "out of memory" conditions to to accept the 32-bit memory configuration choices on 64-bit deployments.  The significant configuration choices are: Maximum process data (heap) size is in an AIX environment variableLDR_CNTRL=IGNOREUNLOAD@LOADPUBLIC@PREREAD_SHLIB@MAXDATA=0x... Two thread stack sizes are made in obiee NQSConfig.INI[ SERVER ]SERVER_THREAD_STACK_SIZE = 0;DB_GATEWAY_THREAD_STACK_SIZE = 0; Sort memory in NQSConfig.INI[ GENERAL ]SORT_MEMORY_SIZE = 4 MB ;SORT_BUFFER_INCREMENT_SIZE = 256 KB ; Choosing a value for MAXDATA:0x080000000  2GB Default maximum 32-bit heap size ( 8 with 7 zeros )0x100000000  4GB 64-bit breaking even with 32-bit ( 1 with 8 zeros )0x200000000  8GB 64-bit double 32-bit max0x400000000 16GB 64-bit safetyUsing 2GB heap size for a 64-bit process will almost certainly lead to an out-of-memory situation.Registers are twice as big ... consume twice as much memory in the heap.Upgrading to a 4GB heap for a 64-bit process is just "breaking even" with 32-bit.A 32-bit process is constrained by the 32-bit virtual addressing limits.  Heap memory is used for dynamic requirements of obiee software, thread stacks for each of the configured threads, and sometimes for shared libraries. 64-bit processes are not constrained in this way;  extra heap space can be configured for safety against a query that might create a sudden requirement for excessive storage.  If the storage is not available, this query might crash the whole server and disrupt existing users.There is no performance penalty on AIX for configuring more memory than required;  extra memory can be configured for safety.  If there are no other considerations, start with 8GB.Choosing a value for Thread Stack size:zero is the value documented to select an appropriate default for thread stack size.  My preference is to change this to an absolute value, even if you intend to use the documented default;  it provides better documentation and removes the "surprise" factor.There are two thread types that can be configured. GATEWAY is used by a thread pool to call a database client library to establish a DB connection.The default size is 256KB;  many customers raise this to 512KB ( no performance penalty for over-configuring ). This value must be set to 1 MB if Teradata connections are used. SERVER threads are used to run queries.  OBIEE uses recursive algorithms during the analysis of query structures which can consume significant thread stack storage.  It's difficult to provide guidance on a value that depends on data and complexity.  The general notion is to provide more space than you think you need,  "double down" and increase the value if you run out, otherwise inspect the query to understand why it is too complex for the thread stack.  There are protections built into the software to abort a single user query that is too complex, but the algorithms don't cover all situations.256 KB  The default 32-bit stack size.  Many customers increased this to 512KB on 32-bit.  A 64-bit server is very likely to crash with this value;  the stack contains mostly register values, which are twice as big.512 KB  The documented 64-bit default.  Some early releases of obiee didn't set this correctly, resulting in 256KB stacks.1 MB  The recommended 64-bit setting.  If your system only ever uses 512KB of stack space, there is no performance penalty for using 1MB stack size.2 MB  Many large customers use this value for safety.  No performance penalty.nqscheduler does not use the NQSConfig.INI file to set thread stack size.If this process crashes because the thread stack is too small, use this to set 2MB:export OBI_BACKGROUND_STACK_SIZE=2048 Shared libraries are not (shared) When application libraries are loaded at run-time, AIX makes a decision on whether to load the libraries in a "public" memory segment.  If the filesystem library permissions do not have the "Read-Other" permission bit, AIX loads the library into private process memory with two significant side-effects:* The libraries reduce the heap storage available.      Might be significant in 32-bit processes;  irrelevant in 64-bit processes.* Library code is loaded into multiple real pages for execution;  one copy for each process.Multiple execution images is a significant issue for both 32- and 64-bit processes.The "real memory pages" saved by using public memory segments is a minor concern.  Today's machines typically have plenty of real memory.The real problem with private copies of libraries is that they consume processor cache blocks, which are limited.   The same library instructions executing in different real pages will cause memory delays as the i-cache ( instruction cache 128KB blocks) are refreshed from real memory.   Performance loss because instructions are delayed is something that is difficult to measure without access to low-level cache fault data.   The machine just appears to be running slowly for no observable reason.This is an easy problem to detect, and an easy problem to correct.Detection:  "genld -l" AIX command produces a list of the libraries used by each process and the AIX memory address where they are loaded.32-bit public segment is 13 ( "dxxxxxxx" ).   private segments are 2-a.64-bit public segment is 9 ( "9xxxxxxxxxxxxxxx") ; private segment is 8.genld -l | grep -v ' d| 9' | sort +2provides a list of privately loaded libraries. Repair: chmod o+r <libname>AIX shared libraries will have a suffix of ".so" or ".a".Another technique is to change all libraries in a selected directory to repair those that might not be currently loaded.   The usual directories that need repair are obiee code, httpd code and plugins, database client libraries and java.chmod o+r /shr/dir/*.a /shr/dir/*.so Configure your system for diagnosticsProduction systems shouldn't crash, and yet bad things happen to good software.If obiee software crashes and produces a core, you should configure your system for reliable transfer of the failing conditions to Oracle Tech Support.  Here's what we need to be able to diagnose a core file from your system.* fullcore enabled. chdev -lsys0 -a fullcore=true* core naming enabled. chcore -n on -d* ulimit must not truncate core. see item 3.* pstack.sh is used to capture core documentation.* obidoc is used to capture current AIX configuration.* snapcore  AIX utility captures core and libraries. Use the proper syntax. $ snapcore -r corename executable-fullpath   /tmp/snapcore will contain the .pax.Z output file.  It is compressed.* If cores are directed to a common directory, ensure obiee userid can write to the directory.  ( chcore -p /cores -d ; chmod 777 /cores )The filesystem must have sufficient space to hold a crashing obiee application.Use:  df -k  Check the "Free" column ( not "% Used" )  8388608 is 8GB. Disable Oracle Client Library signal handlingThe Oracle DB Client Library is frequently distributed with the sqlplus development kit.By default, the library enables a signal handler, which will document a call stack if the application crashes.   The signal handler is not needed, and definitely disruptive to obiee diagnostics.   It needs to be disabled.   sqlnet.ora is typically located at:   $ORACLE_HOME/network/admin/sqlnet.oraAdd this line at the top of the file:   DIAG_SIGHANDLER_ENABLED=FALSE Disable async query in the RPD connection pool.This might be an obiee 10.1.3.4 issue only ( still checking  )."async query" must be disabled in the connection pools.It was designed to enable query cancellation to a database, and turned out to have too many edge conditions in normal communication that produced random corruption of data and crashes.  Please ensure it is turned off in the RPD. Check AIX error report (errpt).Errors external to obiee applications can trigger crashes.  $ /bin/errpt -aHardware errors ( firmware, adapters, disks ) should be reported to IBM support.All application core files are recorded by AIX;  the most recent ones are listed first. Reserved for something important to say.

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• Can I get my video card to output a DVI and VGA signal at the same time?

  - by Roy Pardee

  Hey All, I've got: a lovely 24" monitor, w/both DVI and VGA inputs, a personal desktop w/a Radeon HD Pro 2400 video card (both DVI and VGA outputs) a work laptop w/both outputs, and a KVM switch that handles VGA only Right now I've got laptop connected to the monitor's VGA, and the desktop connected to the DVI. This works, but requires me to switch the KVM and monitor input sources separately, which annoys me (I switch back & forth a lot to make skype calls & manage my music). I'd like to feed both VGA and DVI signals out of my desktop so I can do quick things on my desktop & switch right back, but then when I'm done working, switch the monitor over to DVI to get the crisper picture. Alas, just attaching both VGA and DVI cables to my desktop's video card did not do the trick. Can this card be persuaded to output both signals at the same time? Many thanks! -Roy

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• Does vmWare ESXi 4.0 U1 support the Promise SuperTrak EX8650 SATA card?

  - by RTNN

  Hi, can anyone tell me if vmWare ESXi 4.0 U1 has support for the Promise SuperTrak EX8650 SATA card? In the hardware support guide I find that VmWare should have support for the Promise SuperTrak EX8650 SATA card but only in version ESX 3.5. Is this card not supported for ESXi 4.0 U1 or what? From the hardware guide! Partner Name Model Manufacturer Device Type Supported Releases Promise SuperTrak EX8650 Promise Technology Inc SAS-RAID ESX 3.5 U5*1 1 , ESX 3.5 U4*1 1 Promise SuperTrak EX8760T Promise Technology Inc SAS ESX / ESXi 4.0 U1*2 2 , ESX / ESXi 4.0*2 2

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• Why does 1GBit card have output limited to 80 MiB ?

  - by Gallus

  I'm trying to utilize maximal bandwidth provided by my 1GiB network card, but it's always limited to 80MiB (real megabytes). What can be the reason? Card description (lshw output): description: Ethernet interface product: DGE-530T Gigabit Ethernet Adapter (rev 11) vendor: D-Link System Inc physical id: 0 bus info: pci@0000:03:00.0 logical name: eth1 version: 11 serial: 00:22:b0:68:70:41 size: 1GB/s capacity: 1GB/s width: 32 bits clock: 66MHz capabilities: pm vpd bus_master cap_list rom ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation The card is placed in following PCI slot: *-pci:2 description: PCI bridge product: 82801 PCI Bridge vendor: Intel Corporation physical id: 1e bus info: pci@0000:00:1e.0 version: 92 width: 32 bits clock: 33MHz capabilities: pci subtractive_decode bus_master cap_list The PCI isn't any PCI Express right? It's a legacy PCI slot? So maybe this is the reason? OS is a linux.

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• SATA controller installed but not working? (No drives show up/Don't see card's BIOS)

  - by johnnycakes

  Hi, I have an old Promise FastTrak S150 TX4 SATA controller card. I put it in an old machine running Windows Server 2003. I booted the machine. The new hardware was detected. I installed the drivers. So now in Device Manager under "SCSI and RAID Controllers" I see "Win Server 2003 Promise FastTrak S150 TX4 Controller" and "Win Server 2003 Promise RAID Console SCSI Processor Device" I previously had the card in a machine that is now dead. When I booted that machine, during the boot process I would see the card info displayed and the drives that were attached. Boot would finish and my drives would be available. When I boot this new machine I never see that screen/text. No hard drives are available/visible. What am I missing? Thanks.

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• Is NVIDIA GeForce GTX 480 Video Card Compatbile with a Mac Pro Running Windows 7 Pro 64?

  - by aquat33nfan

  I have a Mac Pro (early 2008) and I'm running Windows 7 Pro (64 bit) natively (i.e., with just Windows installed and no OSX or boot camp) on it. If I buy an NVIDIA GeForce GTX 480 video card, will it work or do I have to buy a card that is Mac-specific (e.g., GeForce GTX 285 'for Mac')? Also, more generally, will Windows video cards work on Intel Macs running Windows (in case I pick a cheaper card)? I can't tell if it matters that a Mac does not have a bios. I searched other boards and I gathered that video cards would work fine because Windows has the proper drivers for them and OSX doesn't and not having the BIOS doesn't make a difference. I found one thread on here that seemed to indicate that as well, but I wanted to make sure. Thanks.

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• How to tell if my sound card is listed in Device Manager?

  - by Bruhan

  The sound on my computer suddenly stopped working. When I check Sounds and Audio Devices in the Control Panel, I get "No Audio Device" with everything grayed out. When I check the Device Manager under "Sound, video and game controllers" I see the following list: Audio Codecs Legacy Audio Drivers Legacy Video Capture Devices Media Control Devices MPU-401 Compatible MIDI Device Standard Game Port Video Codecs None of these looks like my sound card. Of course, my sound "card" is not really a sound card, it's integrated with the nVidia-nForce motherboard. I'm running Windows XP. So is one of the above my sound device, or is the OS not detecting it? If the latter, how do I get it to detect it?

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• How to make a video card use DVI output by default in text mode?

  - by Igor Zinov'yev

  I have an ASUS ENGT440/DI1GD5 video card which has three outputs: DVI, D-Sub and HDMI. I am using both D-Sub and DVI, but my main monitor is connected to the DVI output. Everything works fine except for the text mode. The card somehow uses the D-Sub output in text mode when both monitors are connected (when I disconnect the D-Sub output and leave only the primary monitor connected to the DVI output, it's being used correctly). How do I make the card use only the DVI output (or both) in text mode?

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• VM VirtualBox, Ubuntu 9.10: USB memory stick and SD card not detected...

  - by vikramtheone

  Hello Guys, I have installed Ubuntu9.10 on VM VirtualBox, on my HP laptop. My laptop has several USB ports and also a SD card port. Unfortunately, I'm unable to access both, my pen-drive on the USB port and my 8GB SD card inserted in the SD Card port. Can anyone suggest me what I should do for my Ubuntu to detect both of them? I have installed all latest updates on Ubuntu. I'm able to use my USB mouse. Thank you Vikram

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• Sound issues after trying everything

  - by Lerp

  I cannot get my sound working properly, no matter what I do, there's always some problem. It's very annoying as it's the only thing preventing me from making Ubuntu my main OS. At the moment my sound always plays through both my speakers and my headphones regardless except the sound through the headphones is crackly. It is also a bit quiet even though everything is maxed. I've managed to improve the situation to a point where the sound out of my speakers is perfect but I have none at all from my headphones. I do have two connectors listed in the sound settings but regardless of which one is selected it always plays through the speakers. I think this might have something to do with the fact that my speakers are plugging into the front of my computer, typically the headphone jack, and my headphones are plugging into the back but when I try disconnecting the speakers from the front there is still no sound from the headphones. I fixed the speaker sound by going through the sound settings and making sure they were all set to 100% then rebooting. Things I have tried: Maxing everything and unmuting everything in alsamixer Uninstalling pulseaudio Making gstreamer use only alsa via gstreamer-properties. This worked with the sound test button including independent sound between headphones and speakers but when I reset the computer it no longer worked. So I tried setting it manually in gconf-editor which didn't work either. Reinstalling alsa and pulseaudio Setting the model in /etc/modprobe.d/alsa-base.conf to 6stack and 6stack-dig neither worked. Upgrading to 12.10 Here's some command output to help you diagnose my problem. aplay -l **** List of PLAYBACK Hardware Devices **** card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog] Subdevices: 0/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 1: AD198x Digital [AD198x Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 2: AD198x Headphone [AD198x Headphone] Subdevices: 1/1 Subdevice #0: subdevice #0 sudo lshw -C sound *-multimedia description: Audio device product: 82801JI (ICH10 Family) HD Audio Controller vendor: Intel Corporation physical id: 1b bus info: pci@0000:00:1b.0 version: 00 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: driver=snd_hda_intel latency=0 resources: irq:70 memory:f7ff8000-f7ffbfff cat /proc/asound/card*/codec* | grep "Codec" Codec: Analog Devices AD1989B cat /etc/modprobe.d/alsa-base.conf # autoloader aliases install sound-slot-0 /sbin/modprobe snd-card-0 install sound-slot-1 /sbin/modprobe snd-card-1 install sound-slot-2 /sbin/modprobe snd-card-2 install sound-slot-3 /sbin/modprobe snd-card-3 install sound-slot-4 /sbin/modprobe snd-card-4 install sound-slot-5 /sbin/modprobe snd-card-5 install sound-slot-6 /sbin/modprobe snd-card-6 install sound-slot-7 /sbin/modprobe snd-card-7 # Cause optional modules to be loaded above generic modules install snd /sbin/modprobe --ignore-install snd $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-ioctl32 ; /sbin/modprobe --quiet --use-blacklist snd-seq ; } # # Workaround at bug #499695 (reverted in Ubuntu see LP #319505) install snd-pcm /sbin/modprobe --ignore-install snd-pcm $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-pcm-oss ; : ; } install snd-mixer /sbin/modprobe --ignore-install snd-mixer $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-mixer-oss ; : ; } install snd-seq /sbin/modprobe --ignore-install snd-seq $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; /sbin/modprobe --quiet --use-blacklist snd-seq-oss ; : ; } # install snd-rawmidi /sbin/modprobe --ignore-install snd-rawmidi $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; : ; } # Cause optional modules to be loaded above sound card driver modules install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-emu10k1-synth ; } install snd-via82xx /sbin/modprobe --ignore-install snd-via82xx $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq ; } # Load saa7134-alsa instead of saa7134 (which gets dragged in by it anyway) install saa7134 /sbin/modprobe --ignore-install saa7134 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist saa7134-alsa ; : ; } # Prevent abnormal drivers from grabbing index 0 options bt87x index=-2 options cx88_alsa index=-2 options saa7134-alsa index=-2 options snd-atiixp-modem index=-2 options snd-intel8x0m index=-2 options snd-via82xx-modem index=-2 options snd-usb-audio index=-2 options snd-usb-caiaq index=-2 options snd-usb-ua101 index=-2 options snd-usb-us122l index=-2 options snd-usb-usx2y index=-2 # Ubuntu #62691, enable MPU for snd-cmipci options snd-cmipci mpu_port=0x330 fm_port=0x388 # Keep snd-pcsp from being loaded as first soundcard options snd-pcsp index=-2 # Keep snd-usb-audio from beeing loaded as first soundcard options snd-usb-audio index=-2 options snd-hda-intel model=6stack

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• Wrapping malloc - C

  - by Appu

  I am a beginner in C. While reading git's source code, I found this wrapper function around malloc. void *xmalloc(size_t size) { void *ret = malloc(size); if (!ret && !size) ret = malloc(1); if (!ret) { release_pack_memory(size, -1); ret = malloc(size); if (!ret && !size) ret = malloc(1); if (!ret) die("Out of memory, malloc failed"); } #ifdef XMALLOC_POISON memset(ret, 0xA5, size); #endif return ret; } Questions I couldn't understand why are they using malloc(1)? What does release_pack_memory does and I can't find this functions implementation in the whole source code. What does the #ifdef XMALLOC_POISON memset(ret, 0xA5, size); does? I am planning to reuse this function on my project. Is this a good wrapper around malloc? Any help would be great.

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• Automatically calling OnDetaching() for Silverlight Behaviors

  - by Dan Auclair

  I am using several Blend behaviors and triggers on a silverlight control. I am wondering if there is any mechanism for automatically detaching or ensuring that OnDetaching() is called for a behavior or trigger when the control is no longer being used (i.e. removed from the visual tree). My problem is that there is a managed memory leak with the control because of one of the behaviors. The behavior subscribes to an event on some long-lived object in the OnAttached() override and should be unsubscribing to that event in the OnDetaching() override so that it can become a candidate for garbage collection. However, OnDetaching() never seems to be getting called when I remove the control from the visual tree... the only way I can get it to happen is by explicit detaching the behavior BEFORE removing the control and then it is properly garbage collected. Right now my only solution was to create a public method in the code-behind for the control that can go through and detach any known behaviors that would cause garbage collection problems. It would be up to the client code to know to call this before removing the control from the panel. I don't really like this approach, so I am looking for some automatic way of doing this that I am overlooking or a better suggestion. public void DetachBehaviors() { foreach (var behavior in Interaction.GetBehaviors(this.LayoutRoot)) { behavior.Detach(); } //... //continue detaching all known problematic behaviors.... }

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• Do the ‘up to date’ guarantees for values of Java's final fields extend to indirect references?

  - by mattbh

  The Java language spec defines semantics of final fields in section 17.5: The usage model for final fields is a simple one. Set the final fields for an object in that object's constructor. Do not write a reference to the object being constructed in a place where another thread can see it before the object's constructor is finished. If this is followed, then when the object is seen by another thread, that thread will always see the correctly constructed version of that object's final fields. It will also see versions of any object or array referenced by those final fields that are at least as up-to-date as the final fields are. My question is - does the 'up-to-date' guarantee extend to the contents of nested arrays, and nested objects? An example scenario: Thread A constructs a HashMap of ArrayLists, then assigns the HashMap to final field 'myFinal' in an instance of class 'MyClass' Thread B sees a (non-synchronized) reference to the MyClass instance and reads 'myFinal', and accesses and reads the contents of one of the ArrayLists In this scenario, are the members of the ArrayList as seen by Thread B guaranteed to be at least as up to date as they were when MyClass's constructor completed? I'm looking for clarification of the semantics of the Java Memory Model and language spec, rather than alternative solutions like synchronization. My dream answer would be a yes or no, with a reference to the relevant text.

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• Delete array of size 1

  - by Arne

  This is possibly a candidate for a one-line answer. I would like know it anyway.. I am writing a simple circular buffer and for some reasons that are not important for the question I need to implement it using an array of doubles. In fact I have not investiated other ways to do it, but since an array is required anyway I have not spent much time on looking for alternatives. template<typename T> class CircularBuffer { public: CircularBuffer(unsigned int size); ~CircularBuffer(); void Resize(unsigned int new_size); ... private: T* buffer; unsigned int buffer_size; }; Since I need to have the buffer dynamically sized the buffer_size is neither const nor a template parameter. Now the question: During construction and in function Resize(int) I only require the size to be at least one, although a buffer of size one is effectively no longer a buffer. Of course using a simple double instead would be more appropriate but anyway. Now when deleting the internal buffer in the destructor - or in function resize for that matter - I need to delete the allocated memory. Question is, how? First candidate is of course delete[] buffer; but then again, if I have allocated a buffer of size one, that is if the pointer was aquired with buffer = new T[0], is it still appropriate to call delete[] on the pointer or do I need to call delete buffer; (without brackets) ? Thanks, Arne

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• IPhone custom UITableViewCell Reloading

  - by Steblo

  Hi, currently I'm struggling with this problem: I got a UITableViewController that displays a tableView with different custom cells. One custom cell displays a number (by a label). If you click on this cell, the navigationController moves to a UIPicker where the user can select the number to be displayes. If the user moves back, the cell should display the updated value. Problem: I managed to reload the cells by calling - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; [self.tableView reloadData]; } in the UITableViewController. This works only, if I don't use dequeueReusableCellWithIdentifier for the cell (tables won't show updates otherwise). But in this case, memory usage grows and grows... In addition, the program crashes after about 15 movements to pickerView and back - I think because the cell that should be reloaded is already released. How can I update a reusable custom cell every time the view appears ? What is the best solution ? I think retaining cells should not be used ?

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• C++ stringstream, string, and char* conversion confusion

  - by Graphics Noob

  My question can be boiled down to, where does the string returned from stringstream.str().c_str() live in memory, and why can't it be assigned to a const char*? This code example will explain it better than I can #include <string> #include <sstream> #include <iostream> using namespace std; int main() { stringstream ss("this is a string\n"); string str(ss.str()); const char* cstr1 = str.c_str(); const char* cstr2 = ss.str().c_str(); cout << cstr1 // Prints correctly << cstr2; // ERROR, prints out garbage system("PAUSE"); return 0; } The assumption that stringstream.str().c_str() could be assigned to a const char* led to a bug that took me a while to track down. For bonus points, can anyone explain why replacing the cout statement with cout << cstr // Prints correctly << ss.str().c_str() // Prints correctly << cstr2; // Prints correctly (???) prints the strings correctly? I'm compiling in Visual Studio 2008.

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• Weak event handler model for use with lambdas

  - by Benjol

  OK, so this is more of an answer than a question, but after asking this question, and pulling together the various bits from Dustin Campbell, Egor, and also one last tip from the 'IObservable/Rx/Reactive framework', I think I've worked out a workable solution for this particular problem. It may be completely superseded by IObservable/Rx/Reactive framework, but only experience will show that. I've deliberately created a new question, to give me space to explain how I got to this solution, as it may not be immediately obvious. There are many related questions, most telling you you can't use inline lambdas if you want to be able to detach them later: Weak events in .Net? Unhooking events with lambdas in C# Can using lambdas as event handlers cause a memory leak? How to unsubscribe from an event which uses a lambda expression? Unsubscribe anonymous method in C# And it is true that if YOU want to be able to detach them later, you need to keep a reference to your lambda. However, if you just want the event handler to detach itself when your subscriber falls out of scope, this answer is for you.

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• Java: volatile guarantees and out-of-order execution

  - by WizardOfOdds

  Note that this question is solely about the volatile keyword and the volatile guarantees: it is not about the synchronized keyword (so please don't answer "you must use synchronize" for I don't have any issue to solve: I simply want to understand the volatile guarantees (or lack of guarantees) regarding out-of-order execution). Say we have an object containing two volatile String references that are initialized to null by the constructor and that we have only one way to modify the two String: by calling setBoth(...) and that we can only set their references afterwards to non-null reference (only the constructor is allowed to set them to null). For example (it's just an example, there's no question yet): public class SO { private volatile String a; private volatile String b; public SO() { a = null; b = null; } public void setBoth( @NotNull final String one, @NotNull final String two ) { a = one; b = two; } public String getA() { return a; } public String getB() { return b; } } In setBoth(...), the line assigning the non-null parameter "a" appears before the line assigning the non-null parameter "b". Then if I do this (once again, there's no question, the question is coming next): if ( so.getB() != null ) { System.out.println( so.getA().length ); } Am I correct in my understanding that due to out-of-order execution I can get a NullPointerException? In other words: there's no guarantee that because I read a non-null "b" I'll read a non-null "a"? Because due to out-of-order (multi)processor and the way volatile works "b" could be assigned before "a"? volatile guarantees that reads subsequent to a write shall always see the last written value, but here there's an out-of-order "issue" right? (once again, the "issue" is made on purpose to try to understand the semantics of the volatile keyword and the Java Memory Model, not to solve a problem).

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• LocalAlloc and LocalRealloc usage

  - by PaulH

  I have a Visual Studio 2008 C++ Windows Mobile 6 application where I'm using a FindFirst() / FindNext() style API to get a collection of items. I do not know how many items will be in the list ahead of time. So, I would like to dynamically allocate an array for these items. Normally, I would use a std::vector<>, but, for other reasons, that's not an option for this application. So, I'm using LocalAlloc() and LocalReAlloc(). What I'm not clear on is if this memory should be marked fixed or moveable. The application runs fine either way. I'm just wondering what's 'correct'. int count = 0; INFO_STRUCT* info = ( INFO_STRUCT* )LocalAlloc( LHND, sizeof( INFO_STRUCT ) ); while( S_OK == GetInfo( &info[ count ] ) { ++count; info = ( INFO_STRUCT* )LocalRealloc( info, sizeof( INFO_STRUCT ) * ( count + 1 ), LHND ); } if( count > 0 ) { // use the data in some interesting way... } LocalFree( info ); Thanks, PaulH

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• understanding valgrind output

  - by sbsp

  Hi, i made a post earlier asking about checking for memory leaks etc, i did say i wasnt to familiar with the terminal in linux but someone said to me it was easy with valgrind i have managed to get it running etc but not to sure what the output means. Glancing over, all looks good to me but would like to run it past you experience folk for confirmation if possible. THe output is as follows ^C==2420== ==2420== HEAP SUMMARY: ==2420== in use at exit: 2,240 bytes in 81 blocks ==2420== total heap usage: 82 allocs, 1 frees, 2,592 bytes allocated ==2420== ==2420== LEAK SUMMARY: ==2420== definitely lost: 0 bytes in 0 blocks ==2420== indirectly lost: 0 bytes in 0 blocks ==2420== possibly lost: 0 bytes in 0 blocks ==2420== still reachable: 2,240 bytes in 81 blocks ==2420== suppressed: 0 bytes in 0 blocks ==2420== Reachable blocks (those to which a pointer was found) are not shown. ==2420== To see them, rerun with: --leak-check=full --show-reachable=yes ==2420== ==2420== For counts of detected and suppressed errors, rerun with: -v ==2420== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 13 from 8) Is all good here? the only thing concerning me is the still reachable part. Is that ok? Thanks everyone

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