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  • how can c# help in drawing using memory layers concept?

    - by moon
    hello all i am facing problem in drawing dynamically in a picture box. i works very good when the drawing objects are few but as the drawing objects increases the response time of my GUI is getting worse and worse, my GUI works very well up to 90 drawing objects but i have to support more than 1000 so this technique didn't work for me. know i have decided to adopt layers mechanism, i mean i will draw different layers of drawing in memory and then XOR them to load the final image to my display. the question is "i Can play directly with memory do draw layers using C# (Examples needed?)" other ideas are also appreciated, (Drawing objects means the shapes line,circles etc. that i have to draw on my GUI) thanx in advance

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  • Will it use more and more memory if I keep drawing on the UIView?

    - by Tattat
    This is my drawRect: CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(context, 2.0); CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor); CGContextMoveToPoint(context, x1, y1); CGContextAddLineToPoint(context, x2, y2); CGContextStrokePath(context); If I run this code thousand times or more. My UIView will have many lines on that. Will it use more memory than only just one line on it? Er... ...I mean, will the program remember the line I draw or after it draw the lines, it won't have any information in the memory. thz .

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  • How can I avoid "Your system is running low on virtual memory" pop-up?

    - by Xavier Nodet
    Our application sometimes uses a lot of memory, and this is expected. But when we test it under high load on Windows XP, we usually get the very annoying "Your system is running low on virtual memory" popup, and this prevents our automated, unattended, tests to run through... Is it possible to prevent this popup to appear, and just have the allocation fail? The app will handle it gracefully, and tests will go on... We are using Windows XP, but if a solution only exists on later versions, I'd be happy to know anyway.

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  • ASP.NET web services leak memory when (de)serializing disposable objects?

    - by Serilla
    In the following two cases, if Customer is disposable (implementing IDisposable), I believe it will not be disposed by ASP.NET, potentially being the cause of a memory leak: [WebMethod] public Customer FetchCustomer(int id) { return new Customer(id); } [WebMethod] public void SaveCustomer(Customer value) { // save it } This flaw applies to any IDisposable object. So returning a DataSet from a ASP.NET web service, for example, will also result in a memory leak - the DataSet will not be disposed. In my case, Customer opened a database connection which was cleaned up in Dispose - except Dispose was never called resulting in loads of unclosed database connections. I realise there a whole bunch of bad practices being followed here (its only an example anyway), but the point is that ASP.NET - the (de)serializer - is responsible for disposing these objects, so why doesn't it? This is an issue I was aware of for a while, but never got to the bottom of. I'm hoping somebody can confirm what I have found, and perhaps explain if there is a way of dealing with it.

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  • Need to allocate memory before a Delphi string copy?

    - by Duncan
    Do I need to allocate memory when performing a Delphi string copy? I've a function which posts a Windows message to another form in my application. It looks something like this: // Note: PThreadMessage = ^TThreadMessage; TThreadMessage = String; function PostMyMessage( aStr : string ); var gMsgPtr : PThreadMessage; gStrLen : Integer; begin New(gMsgPtr); gStrLen := StrLen(PWideChar(aMsg)); gMsgPtr^ := Copy(aMsg, 0, gStrLen); PostMessage(ParentHandle, WM_LOGFILE, aLevel, Integer(gMsgPtr)); // Prevent Delphi from freeing this memory before consumed. LParam(gMsgPtr) := 0; end;

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  • What is the best solution to replace a new memory allocator in an existing code?

    - by O. Askari
    During the last few days I've gained some information about memory allocators other than the standard malloc(). There are some implementations that seem to be much better than malloc() for applications with many threads. For example it seems that tcmalloc and ptmalloc have better performance. I have a C++ application that uses both malloc and new operators in many places. I thought replacing them with something like ptmalloc may improve its performance. But I wonder how does the new operator act when used in C++ application that runs on Linux? Does it use the standard behavior of malloc or something else? What is the best way to replace the new memory allocator with the old one in the code? Is there any way to override the behavior or new and malloc or do I need to replace all the calls to them one by one?

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  • Does remove a DOM object (in Javascript) will cause Memory leak if it has event attached?

    - by seatoskyhk
    So, if in the javascript, I create a DOM object in the HTML page, and attach event listener to the DOM object, upon I remove the the DOM from HTML page, does the event listener still exist and causing memory leak? function myTest() { var obj = document.createElement('div'); obj.addEventListener('click', function() {alert('whatever'); }); var body = document.getElementById('body'); // assume there is a <div id='body'></div> already body.appendChild(obj); } // then after some user actions. I call this: function emptyPage() { var body = document.getElementById('body'); body.innerHTML = ''; //empty it. } So, the DOM object, <div> inside body is gone. But what about the eventlistener? I'm just afraid that it will cause memory leak.

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  • Thread Synchronisation 101

    - by taspeotis
    Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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  • Spin-off of "Project: Memory++" in Khan academy [on hold]

    - by smraj
    This is the link of the program that I am trying https://www.khanacademy.org/cs/memory-tile-game/5966959895642112 When I am placing the mouse over the block it should change to red colour and when it is released the image should be displayed but my issue is that when i place the mouse over the block it changes its color ,but on release the image is not displayed.I kindly request someone in solving this

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  • Slab uses 88Gb of 128Gb available. What could cause this?

    - by Joris Meys
    We run a debian 2.6.26-2-amd64 x86_64 GNU/Linux on a server with 128 Gb. Recently it our available memory became rather low. Looking at the /proc/meminfo showed that the Slab was using 88Gb, which is counted in the used memory off course. Is this a problem? I suspect that memory will be freed when necessary, but I don't know if that could have unwanted side effects. Why would Slab need that much memory? Is there a clear cause for that? can we avoid this to happen in the future? How can we free this memory? thank you in advance > cat /proc/meminfo MemTotal: 132304500 kB MemFree: 26669388 kB Buffers: 237504 kB Cached: 11881136 kB SwapCached: 48 kB Active: 5244640 kB Inactive: 11714308 kB SwapTotal: 5751228 kB SwapFree: 5750436 kB Dirty: 24 kB Writeback: 0 kB AnonPages: 4840256 kB Mapped: 163968 kB Slab: 88314840 kB SReclaimable: 88275644 kB SUnreclaim: 39196 kB PageTables: 80852 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 71903476 kB Committed_AS: 6818332 kB VmallocTotal: 34359738367 kB VmallocUsed: 505724 kB VmallocChunk: 34359231963 kB

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  • Ubuntu 12.04 NVIDIA GeForce Go 7600 black screen during boot

    - by Florian Schmidt
    I'm using Ubuntu as the only operating system since two years. In the first Ubuntu versions I had seen my BIOS screen and the boot screens. Actually im using Ubuntu 12.04 and my screen stays black until Ubuntu is started (both screens are missing). I guess this situation appeared the first time in Ubuntu 11 (not sure). I searched via google and tried the popular activities but was not able to fix my issue. I opened the laptop and checked all connections. I'm using boot option nomodeset. I had a look through many many web pages. I don't know how to continue and hope somebody could be helpful. My hardware: Acer Aspire 9300 AMD Turion 64 x2 NVIDIA GeForce Go 7600 (using proposed driver) lspci | grep NVIDIA 00:00.0 RAM memory: NVIDIA Corporation C51 Host Bridge (rev a2) 00:00.1 RAM memory: NVIDIA Corporation C51 Memory Controller 0 (rev a2) 00:00.2 RAM memory: NVIDIA Corporation C51 Memory Controller 1 (rev a2) 00:00.3 RAM memory: NVIDIA Corporation C51 Memory Controller 5 (rev a2) 00:00.4 RAM memory: NVIDIA Corporation C51 Memory Controller 4 (rev a2) 00:00.5 RAM memory: NVIDIA Corporation C51 Host Bridge (rev a2) 00:00.6 RAM memory: NVIDIA Corporation C51 Memory Controller 3 (rev a2) 00:00.7 RAM memory: NVIDIA Corporation C51 Memory Controller 2 (rev a2) 00:02.0 PCI bridge: NVIDIA Corporation C51 PCI Express Bridge (rev a1) 00:03.0 PCI bridge: NVIDIA Corporation C51 PCI Express Bridge (rev a1) 00:04.0 PCI bridge: NVIDIA Corporation C51 PCI Express Bridge (rev a1) 00:09.0 RAM memory: NVIDIA Corporation MCP51 Host Bridge (rev a2) 00:0a.0 ISA bridge: NVIDIA Corporation MCP51 LPC Bridge (rev a3) 00:0a.1 SMBus: NVIDIA Corporation MCP51 SMBus (rev a3) 00:0a.3 Co-processor: NVIDIA Corporation MCP51 PMU (rev a3) 00:0b.0 USB controller: NVIDIA Corporation MCP51 USB Controller (rev a3) 00:0b.1 USB controller: NVIDIA Corporation MCP51 USB Controller (rev a3) 00:0d.0 IDE interface: NVIDIA Corporation MCP51 IDE (rev f1) 00:0e.0 IDE interface: NVIDIA Corporation MCP51 Serial ATA Controller (rev f1) 00:10.0 PCI bridge: NVIDIA Corporation MCP51 PCI Bridge (rev a2) 00:10.1 Audio device: NVIDIA Corporation MCP51 High Definition Audio (rev a2) 00:14.0 Bridge: NVIDIA Corporation MCP51 Ethernet Controller (rev a3) 03:00.0 VGA compatible controller: NVIDIA Corporation G73 [GeForce Go 7600] (rev a1) So my question is what to do to fix the black screen during boot?

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  • Task Manager: VM Size smaller than Mem usage?

    - by shoosh
    The windows XP tasks manager can show two different columns regarding the memory usage of the processes. One is called Mem Usage and the other is VM Size (not on by default, you need to activate it) From what I've gathered, VM size is the size of the entire memory space occupied by the process and Mem Usage is the amount of memory currently committed and used. This assumption is verified by most processes when the VM Size is only slightly larger than Mem Usage for instance my Outlook currently has 79,724 K in VM Size and 56,600 K in Mem Usage But it fails for other processes such as Firefox which currently has 171,900 K for Mem Usage and only 156,440 K in VM Size. How can a process use more memory than the amount of virtual memory allocated to it? So Maybe my interpretation of these columns is wrong. What do they actually mean?

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  • Tab Sweep: Email, AntClassLoader, CouchBase Manager, Memory Usage, ...

    - by arungupta
    Recent Tips and News on Java, Java EE 6, GlassFish & more : • Java, GlassFish v3, High CPU and Memory Usage, Locked Threads, Death (Gregor Bowie) • Why I will continue to use Spring *and* Java EE in new Enterprise Java Projects in 2012/2013 (Nikos Maravitsas) • The Most Frequently Asked Question About Java EE 6 & NetBeans (Geertjan) • AntClassLoader bug exposed by forgetful NetBeans (Vince) • Quick Fix for GlassFish/MySQL NoPasswordCredential Found (Mark Heckler) • Sending email via Glassfish v3 (Zbynek Šlajchrt) • COUCHBASE MANAGER FOR GLASSFISH: MORE TESTS (Ricky Poderi)

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  • Investigating .NET Memory Management and Garbage Collection

    Investigating a subtle memory leak can be tricky business, but things are made easier by using The .NET framework's tool SOS (Son of Strike) which is a debugger extension for debugging managed code, used in collaboration with the Windows debugger....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • w3wp.exe (ASP .Net) eating memory (2 replies)

    Hello, i'm on a VPS with Windows 2003 x64 (IIS 6.0 so) and i have a serious problem with w3wp.exe. It starts from 60 Mb and then grows until the whole avaiable RAM is used. http://img32.imageshack.us/img32/4120/w3wpgraph.png Here's an example image showing w3wp.exe private bytes and Gen 0 Heap size. They seems related, but if I use &quot;.NET CLR Memory/# Bytes in all Heaps &quot; it is much lower than priv...

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  • Current trends in Random Access Memory

    - by Nutel
    As I know for now because of laws of Physics there will be not any tangible improvements in CPU cycles per second for the nearest future. However because of Von Neumann bottleneck it seems to not be an issue for non-server applications. So what about RAM, is there any upcoming technologies that promise to improve memory speed or we are stack with the current situation till quantum computers will come out from labs?

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  • CVE-2012-0444 Memory corruption vulnerability in Ogg Vorbis

    - by chandan
    CVE DescriptionCVSSv2 Base ScoreComponentProduct and Resolution CVE-2012-0444 Memory corruption vulnerability 10.0 libvorbis Solaris 11 11/11 SRU 8.5 Solaris 10 SPARC: 148006-01 X86: 148007-01 This notification describes vulnerabilities fixed in third-party components that are included in Sun's product distribution.Information about vulnerabilities affecting Oracle Sun products can be found on Oracle Critical Patch Updates and Security Alerts page.

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