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  • Why is the W3C box model considered better?

    - by Mel
    Why do most developers consider the W3C box-model to be better than the box-model used by Internet Explorer? I know it's very frustrating developing pages that look the way you want them on Internet Explorer, but I find the W3C box-model to be counter-intuitive. For example, if margins, padding, and border were factored into the width, I could assign fixed width values for all my columns without having to worry about how many columns I have and what changes I make to my padding and margins. Under W3C box model I have to worry about how many columns I have, and develop something akin to a mathematical formula to calculate my values. Changing them would nightmarish, especially for complex layouts. My novice opinion is that it's more restrictive. Consider this small frame-work I wrote: #content { margin:0 auto 30px auto; padding:0 30px 30px 30px; width:900px; } #content .column { float:left; margin:0 20px 20px 20px; } #content .first { margin-left:0; } #content .last { margin-right:0; } .width_1-4 { width:195px; } .width_1-3 { width:273px; } .width_1-2 { width:430px; } .width_3-4 { width:645px; } .width_1-1 { width:900px; } These values I have assigned here will falter unless there are three columns, and thus the margins at 0(first)+20+20+20+20+0(last). It would be a disaster if I wanted to add padding to my columns too, as my entire setup would have to be re calibrated. Now imagine if column width incorporated all the other elements, all I would need to do is change one associated value, and I have my layout. I'm less criticizing it and more hoping to understand why it's better, or why I'm finding it more difficult. Am I doing this whole thing wrong? I don't know very much about this topic, but it seems counter intuitive to use W3C's box-model. Some advice would be really appreciated. Thanks

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  • read-only memory and heap memory

    - by benjamin button
    hi, AFAIK, string literals are stored in read only memory in case of C language. where is this actually present on the hardware. as per my knowledge heap is on RAM.correct me if i am wrong. how different is heap from read only memory? is it OS dependant?

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  • iPhone memory management

    - by Prazi
    I am newbie to iPhone programming. I am not using Interface Builder in my programming. I have some doubt about memory management, @property topics in iPhone. Consider the following code @interface LoadFlag : UIViewController { UIImage *flag; UIImageView *preview; } @property (nonatomic, retain) UIImageView *preview; @property (nonatomic, retain) UIImage *flag; @implementation @synthesize preview; @synthesize flag; - (void)viewDidLoad { flag = [UIImage imageNamed:@"myImage.png"]]; NSLog(@"Preview: %d\n",[preview retainCount]); //Count: 0 but shouldn't it be 1 as I am retaining it in @property in interface file preview=[[UIImageView alloc]init]; NSLog(@"Count: %d\n",[preview retainCount]); //Count: 1 preview.frame=CGRectMake(0.0f, 0.0f, 100.0f, 100.0f); preview.image = flag; [self.view addSubview:preview]; NSLog(@"Count: %d\n",[preview retainCount]); //Count: 2 [preview release]; NSLog(@"Count: %d\n",[preview retainCount]); //Count: 1 } When & Why(what is the need) do I have to set @property with retain (in above case for UIImage & UIImageView) ? I saw this statement in many sample programs but didn't understood the need of it. When I declare @property (nonatomic, retain) UIImageView *preview; statement the retain Count is 0. Why doesn't it increase by 1 inspite of retaining it in @property. Also when I declare [self.view addSubview:preview]; then retain Count increments by 1 again. In this case does the "Autorelease pool" releases for us later or we have to take care of releasing it. I am not sure but I think that the Autorelease should handle it as we didn't explicitly retained it so why should we worry of releasing it. Now, after the [preview release]; statement my count is 1. Now I don't need UIImageView anymore in my program so when and where should I release it so that the count becomes 0 and the memory gets deallocated. Again, I am not sure but I think that the Autorelease should handle it as we didn't explicitly retained it so why should we worry of releasing it. What will happen if I release it in -(void) dealloc method In the statement - flag = [UIImage imageNamed:@"myImage.png"]]; I haven't allocated any memory to flag but how can I still use it in my program. In this case if I do not allocate memory then who allocates & deallocates memory to it or is the "flag" just a reference pointing to - [UIImage imageNamed:@"myImage.png"]];. If it is a reference only then do i need to release it. Thanks in advance.

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  • ARC, worth it or not?

    - by MSK
    When I moved to Objective C (iOS) from C++ (and little Java) I had hard time understanding memory management in iOS. But now all this seems natural and I know retain, autorelease, copy and release stuff. After reading about ARC, I am wondering is there more benefits of using ARC or it is just that you dont have to worry about memory management. Before moving to ARC I wanted to know how worth is moving to ARC. XCode has "Convert to Objective C ARC" menu. Is the conversion is that simple (nothing to worry about)? Does it help me in reducing my apps memory foot-print, memory leaks etc (somehow ?) Does it has much testing impact on my apps ? What are non-obvious advantages? Any Disadvantage os moving to it?

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  • Instantiate a model when the kind of model needed is represented as a string argument

    - by indiehacker
    My input data is a string representing the kind of datastore model I want to make. In python, I am using the eval() function to instantiate the model (below code), but this seems overly complex so I was wondering if there is a simpler way people normally do this? >>>model_kind="TextPixels" >>>key_name_eval="key_name" >>>key_name="key_name" >>>kwargs {'lat': [0, 1, 2, 3], 'stringText': 'boris,ted', 'lon': [0, 1, 2, 8], 'zooms': [0, 10]} >>>obj=eval( model_type + '(key_name='+tester+ ',**kwargs )' ) >>>obj <datamodel.TextPixels object at 0xed8808c>

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  • Linux configurations that would affect Java memory usage?

    - by wmacura
    Hi, Background: I have a set of java background workers I start as part of my webapp. I develop locally on Ubuntu 10.10 and deploy to an Ubuntu 10.04LTS server (a media temple (ve) instance). They're both running the same JVM: Sun JVM 1.6.0_22-b04. As part of the initialization script each worker is started with explicit Xmx, Xms, and XX:MaxPermGen settings. Yet somehow locally all 10 workers use 250MB, while on the server they use more than 2.7GB. I don't know how to begin to track this down. I thought the Ubuntu (and thus, kernel) version might make a difference, but I tried an old 10.04 VM and it behaves as expected. I've noticed that the machine does not seem to ever use memory for buffer or cache (according to htop), which seems a bit strange, but perhaps normal for a server? (edited) Some info: (server) root@devel:/app/axir/target# uname -a Linux devel 2.6.18-028stab069.5 #1 SMP Tue May 18 17:26:16 MSD 2010 x86_64 GNU/Linux (local) wiktor@beastie:~$ uname -a Linux beastie 2.6.35-25-generic #44-Ubuntu SMP Fri Jan 21 17:40:44 UTC 2011 x86_64 GNU/Linux (edited) Comparing PS output: (ps -eo "ppid,pid,cmd,rss,sz,vsz") PPID PID CMD RSS SZ VSZ (local) 1588 1615 java -cp axir-distribution. 25484 234382 937528 1615 1631 java -cp /home/wiktor/Code/ 83472 163059 652236 1615 1657 java -cp /home/wiktor/Code/ 70624 89135 356540 1615 1658 java -cp /home/wiktor/Code/ 37652 77625 310500 1615 1669 java -cp /home/wiktor/Code/ 38096 77733 310932 1615 1675 java -cp /home/wiktor/Code/ 37420 61395 245580 1615 1684 java -cp /home/wiktor/Code/ 38000 77736 310944 1615 1703 java -cp /home/wiktor/Code/ 39180 78060 312240 1615 1712 java -cp /home/wiktor/Code/ 38488 93882 375528 1615 1719 java -cp /home/wiktor/Code/ 38312 77874 311496 1615 1726 java -cp /home/wiktor/Code/ 38656 77958 311832 1615 1727 java -cp /home/wiktor/Code/ 78016 89429 357716 (server) 22522 23560 java -cp axir-distribution. 24860 285196 1140784 23560 23585 java -cp /app/axir/target/a 100764 161629 646516 23560 23667 java -cp /app/axir/target/a 72408 92682 370728 23560 23670 java -cp /app/axir/target/a 39948 97671 390684 23560 23674 java -cp /app/axir/target/a 40140 81586 326344 23560 23739 java -cp /app/axir/target/a 39688 81542 326168 They look very similar. In fact, the question now is why, if I add up the virtual memory usage on the server (3.2GB) does it more closely reflect 2.4GB of memory used (according to free), yet locally the virtual memory used adds up to a much more substantial 4.7GB but only actually uses ~250MB. It seems that perhaps memory isn't being shared as aggressively. (if that's even possible) Thank you for your help, Wiktor

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  • New 64 bit linux system has regular processes (ps, grep etc) taking up way too much VIRT mem

    - by user42980
    We just moved from a 32-bit machine to a 64-bit machine. We have quickly ran out of memory despite the new boxes have twice as much ram as the old boxes. Running a simple ps command will illustrate the problem. New machine: 132 prod-Charlotte1-node1 ~/public_html/rearch/cgi-bin ps aux | grep ps root 293 0.0 0.0 0 0 ? S< May09 0:00 [kpsmoused] xamine 2267 1.0 0.0 63728 928 pts/3 R+ 16:50 0:00 ps aux xamine 2268 0.0 0.0 61172 752 pts/3 S+ 16:50 0:00 grep ps Old machine: 132 prod-116431-node1:/home/xamine ps aux | grep ps xamine 23191 0.0 0.0 2332 768 pts/6 R+ 15:41 0:00 ps aux xamine 23192 0.0 0.0 3668 692 pts/6 S+ 15:41 0:00 grep ps Notice that the ps process is using 63M of VIRT mem vs 2 on the old machine. New Machine: Enterprise Linux Enterprise Linux Server release 5.4 (Carthage) Red Hat Enterprise Linux Server release 5.4 (Tikanga) Old Machine: Red Hat Enterprise Linux ES release 4 (Nahant Update 4) Thanks for any thoughts you have!

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  • Any dangers in using DDR memory with a higher frequency than the FSB?

    - by raw_noob
    I'm looking to upgrade memory in an older motherboard. The processor is an AMD Sempron 2500+ with a maximum speed of 333/166MHz. The motherboard is an MSI MS-7061 (KV3M-V), which accepts up to 2Gb of DDR memory maximum PC2700 in 2 slots and has a maximum FSB of 333MHz. The board does not have dual-channel support. Existing memory includes a stick of 512Mb PC3200, which seems to be running OK (presumably at PC2700) but is rated 200MHz, which is below the FSB speed. The other stick is 256Mb PC2100/133MHz, again below the FSB speed. (All figures from CPU-Z.) I have a chance to acquire a single used stick of PC3200/400MHz memory very cheaply. Crucial's system scanner seems to suggest that this will be OK with my system, but other sites have suggested that running memory with a higher frequency than the FSB can cause instability. Is this true? Would I be better waiting until I can buy the correct PC2700/333MHz stick? I'm assuming that the mixed memory I have at present is running as 768Mb at 133MHz. Is this a reasonable assumption? If so, would you expect the performance differences between 768Mb/133MHz and 1Gb/333MHz to be very noticeable? If I install the new 1Gb/400 or 333MHz stick in slot 1, am I right in thinking that adding back the existing 512Mb/200MHz stick in slot 2 would pull the whole 1.5Gb system memory speed down to 200MHz? If so, which would be better - 1.5Gb/200MHz, or the single 1Gb stick at the full 333MHz that the FSB permits? Is more headroom more important than extra speed? Any help - or even opinions - gratefully received. I can't find reliable information, and I can't afford to make expensive mistakes.

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  • Why do I get swap space related errors when I still have lots of free memory in Solaris 10?

    - by Tom Duckering
    I am seeing a few of my services suffering/crashing with errors along the lines of "Error allocating memory" or "Can't create new process" etc. I'm slightly confused by this since logs show that at the time the system has lots of free memory (around 26GB in one case) of memory available and is not particularly stressed in any other way. After noting a JVM crash with similar error with the added query of "Out of swap space?" it made me dig a little deeper. It turns out that someone has configured our zone with a 2GB swap file. Our zone doesn't have capped memory and currently has access to as much of the 128GB of the RAM as it need. Our SAs are planning to cap this at 32GB when they get the chance. My current thinking is that whilst there is memory aplenty for the OS to allocate, the swap space seems grossly undersized (based on other answers here). It seems as though Solaris is wanting to make sure there's enough swap space in case things have to swap out (i.e. it's reserving the swap space). Is this thinking right or is there some other reason that I get memory allocation errors with this large amount of memory free and seemingly undersized swap space?

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  • How much free memory should I have on my webserver?

    - by neanderslob
    I have a webserver that's currently hosting two Wordpress sites and some java-based collaboration software. The server has 2G of memory and is currently using about 1.8G of the available memory. Right now what's on here is pretty much a pilot project that's getting negligible traffic so I think it's pretty clear that I'll be needing more memory. I was wondering, if I was to release it, how I might anticipate my memory needs based on the traffic it gets. I've poked around on Google and what I've found has been a bit tenuous. Is there a good heuristic that one should use when calculating memory demands as a function of the base (no traffic) load on the server? For reference, the output of free -m can be seen below: total used free shared buffers cached Mem: 2048 1832 215 0 0 0 -/+ buffers/cache: 1832 215 Swap: 0 0 0 To me this looks like actual memory used and isn't an illusion due to caching or anything else. I figure the demands of my collaboration software will have to be experimentally tested so here's free -m without that software running: total used free shared buffers cached Mem: 2048 1109 938 0 0 0 -/+ buffers/cache: 1109 938 Swap: 0 0 0 My plan B to figure this out is to add a bunch of swap space to the server, give it some traffic and adjust according the the amount that swap gets used. I was just wondering if anyone had a good rule of thumb to estimate how much memory I should plan on in advance...or if what I'm thinking is nuts. Many thanks in advance (I'm really quite new to this).

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  • WPF 3.5 RenderTargetBitmap memory hog

    - by kingRauk
    I have a 3.5 WPF application that use's RenderTargetBitmap. It eat's memory like a big bear. It's is a know problem in 3.5 that RenderTargetBitmap.Render has memory problems. Have find some solutions for it, but i doesnt help. https://connect.microsoft.com/VisualStudio/feedback/details/489723/rendertargetbitmap-render-method-causes-a-memory-leak Program takes too much memory And more... Does anyway have any more ideas to solve it... static Image Method(FrameworkElement e, int width, int height) { const int dpi = 192; e.Width = width; e.Height = height; e.Arrange(new Rect(0, 0, width, height)); e.UpdateLayout(); if(element is Graph) (element as Graph).UpdateComponents(); var bitmap = new RenderTargetBitmap((int)(width*dpi/96.0), (int)(height*dpi/96.0), dpi, dpi, PixelFormats.Pbgra32); bitmap.Render(element); var encoder = new PngBitmapEncoder(); encoder.Frames.Add(BitmapFrame.Create(bitmap)); using (var stream = new MemoryStream()) { encoder.Save(stream); element.Clip = null; Dispose(element); bitmap.Freeze(); DisposeRender(bitmap); bitmap.Clear(); GC.Collect(); GC.WaitForPendingFinalizers(); return System.Drawing.Image.FromStream(stream); } } public static void Dispose(FrameworkElement element) { GC.Collect(); GC.WaitForPendingFinalizers(); GC.Collect(); } public static void DisposeRender(RenderTargetBitmap bitmap) { if (bitmap != null) bitmap.Clear(); bitmap = null; GC.Collect(); GC.WaitForPendingFinalizers(); }

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  • Report Model; problem regarding many-to-many relations

    - by Koen
    I'm having trouble setting up a report model to create reports with report builder. I guess I'm doing something wrong when configuring the report model, but it might also due to change of primary entity in report builder. I have 3 tables: Client, Address and Product. The Client has PK ClientNumber. The Address and Product both have a FK relation on ClientNumber. The relation between Client and Address is 1-to-many and also between Client and Product: Product-(many:1)-Client-(1:many)-Address. I've created a report model (mostly auto generate) with these 3 tables, for each table I've made an Entity. Now on the Client Entity , I've got 2 roles, Address and Product. They both have a cardinality of 'OptionalMany', because Client can have multiple Addresses or Products. On both Address and Product I have a Client Role with cardinality 'One', because for each Address or Product, there has to be a Client (tried OptionalOne as well...). Now I'm trying to create a report in Report Builder (2.0) where I select fields from these three entities. I'd like an overview of Clients with their main address and their products, but I don't seem to be able to create a report with fields from both Address and Products in it. I start by selecting attributes from Client, and as soon as I add Product for example the Primary entity changes as if I'm selecting Products (instead of Clients). This is a basic example of a problem I'm facing in a much more complex model. I've tried lots of different things for 2 days, but I can't get it to work. Does anyone have an idea how to cope with this? (Using SSRS 2008)

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  • Instantiating class with custom allocator in shared memory

    - by recipriversexclusion
    I'm pulling my hair due to the following problem: I am following the example given in boost.interprocess documentation to instantiate a fixed-size ring buffer buffer class that I wrote in shared memory. The skeleton constructor for my class is: template<typename ItemType, class Allocator > SharedMemoryBuffer<ItemType, Allocator>::SharedMemoryBuffer( unsigned long capacity ){ m_capacity = capacity; // Create the buffer nodes. m_start_ptr = this->allocator->allocate(); // allocate first buffer node BufferNode* ptr = m_start_ptr; for( int i = 0 ; i < this->capacity()-1; i++ ) { BufferNode* p = this->allocator->allocate(); // allocate a buffer node } } My first question: Does this sort of allocation guarantee that the buffer nodes are allocated in contiguous memory locations, i.e. when I try to access the n'th node from address m_start_ptr + n*sizeof(BufferNode) in my Read() method would it work? If not, what's a better way to keep the nodes, creating a linked list? My test harness is the following: // Define an STL compatible allocator of ints that allocates from the managed_shared_memory. // This allocator will allow placing containers in the segment typedef allocator<int, managed_shared_memory::segment_manager> ShmemAllocator; //Alias a vector that uses the previous STL-like allocator so that allocates //its values from the segment typedef SharedMemoryBuffer<int, ShmemAllocator> MyBuf; int main(int argc, char *argv[]) { shared_memory_object::remove("MySharedMemory"); //Create a new segment with given name and size managed_shared_memory segment(create_only, "MySharedMemory", 65536); //Initialize shared memory STL-compatible allocator const ShmemAllocator alloc_inst (segment.get_segment_manager()); //Construct a buffer named "MyBuffer" in shared memory with argument alloc_inst MyBuf *pBuf = segment.construct<MyBuf>("MyBuffer")(100, alloc_inst); } This gives me all kinds of compilation errors related to templates for the last statement. What am I doing wrong?

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  • How to use bll, dal and model?

    - by bruno
    Dear all, In my company I must use a Bll, Dal and model layer for creating applications with a database. I've learned at school that every databasetable should be an object in my model. so I create the whole model of my database. Also I've learned that for every table (or model object) there should be a DAO created into the DAL. So I do this to. Now i'm stuck with the BLL classes. I can write a BLLclass for each DAO/ModelObject or I can write a BLLclass that combine some (logic) DAO's... Or i can write just one Bllclass that will manage everything. (this last one I'm sure it aint the best way..) What is the best practice to handle this Bll 'problem'? And a second question. If a bll is in need of tablecontent from an other table where it aint responsible for, whats the best way to get the content? Go ask on the responsible BLL or go directly to the DAO? I'm struggling with these questions the last 2 months, and i don't know what is the best way to handle it.

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  • A few questions about a Rails model for a simple addressbook app

    - by user284194
    I have a Rails application that lists information about local services. My objectives for this model are as follows: 1. Require the name and tag_list fields. 2. Require one or more of the tollfreephone, phone, phone2, mobile, fax, email or website fields. 3. If the paddress field has a value, then encode it with the Geokit plugin. Here is my entry.rb model: class Entry < ActiveRecord::Base validates_presence_of :name, :tag_list validates_presence_of :tollfreephone or :phone or :phone2 or :mobile or :fax or :email or :website acts_as_taggable_on :tags acts_as_mappable :auto_geocode=>{:field=>:paddress, :error_message=>'Could not geocode physical address'} before_save :geocode_paddress validate :required_info def required_info unless phone or phone2 or tollfreephone or mobile or fax or email or website errors.add_to_base "Please have at least one form of contact information." end end private def geocode_paddress #if paddress_changed? geo=Geokit::Geocoders::MultiGeocoder.geocode (paddress) errors.add(:paddress, "Could not Geocode address") if ! geo.success self.lat, self.lng = geo.lat,geo.lng if geo.success #end end end Requiring name and tag_list work, but requiring one (or more) of the tollfreephone, phone, phone2, mobile, fax, email or website fields does not. As for encoding with Geokit, in order to save a record with the model I have to enter an address. Which is not the behavior I want. I would like it to not require the paddress field, but if the paddress field does have a value, it should encode the geocode. As it stands, it always tries to geocode the incoming entry. The commented out "if paddress_changed?" was not working and I could not find something like "if paddress_exists?" that would work. Help with any of these issues would be greatly appreciated. I posted three questions pertaining to my model because I'm not sure if they are preventing each other from working. Thank you for reading my questions.

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  • OO Design / Patterns - Fat Model Vs Transaction Script?

    - by ben
    Ok, 'Fat' Model and Transaction Script both solve design problems associated with where to keep business logic. I've done some research and popular thought says having all business logic encapsulated within the model is the way to go (mainly since Transaction Script can become really complex and often results in code duplication). However, how does this work if I want to use the TDG of a second Model in my business logic? Surely Transaction Script presents a neater, less coupled solution than using one Model inside the business logic of another? A practical example... I have two classes: User & Alert. When pushing User instances to the database (eg, creating new user accounts), there is a business rule that requires inserting some default Alerts records too (eg, a default 'welcome to the system' message etc). I see two options here: 1) Add this rule as a User method, and in the process create a dependency between User and Alert (or, at least, Alert's Table Data Gateway). 2) Use a Transaction Script, which avoids the dependency between models. (Also, means the business logic is kept in a 'neutral' class & easily accessible by Alert. That probably isn't too important here, though). User takes responsibility for it's own validation etc, however, but because we're talking about a business rule involving two Models, Transaction Script seems like a better choice to me. Anyone spot flaws with this approach?

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  • why pointer to pointer is needed to allocate memory in function

    - by skydoor
    Hi I have a segmentation fault in the code below, but after I changed it to pointer to pointer, it is fine. Could anybody give me any reason? void memory(int * p, int size) { try{ p = (int *) malloc(size*sizeof(int)); } catch( exception& e) { cout<<e.what()<<endl; } } it does not work in the main function as blow int *p = 0; memory(p, 10); for(int i = 0 ; i < 10; i++) p[i] = i; however, it works like this . void memory(int ** p, int size) { `//pointer to pointer` try{ *p = (int *) malloc(size*sizeof(int)); } catch( exception& e) { cout<<e.what()<<endl; } } int main() { int *p = 0; memory(&p, 10); //get the address of the pointer for(int i = 0 ; i < 10; i++) p[i] = i; for(int i = 0 ; i < 10; i++) cout<<*(p+i)<<" "; return 0; }

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  • ASP.NET MVC - Binding a Child Entity to the Model

    - by Nathan Taylor
    This one seems painfully obvious to me, but for some reason I can't get it working the way I want it to. Perhaps it isn't possible the way I am doing it, but that seems unlikely. This question may be somewhat related: http://stackoverflow.com/questions/1274855/asp-net-mvc-model-binding-related-entities-on-same-page. I have an EditorTemplate to edit an entity with multiple related entity references. When the editor is rendered the user is given a drop down list to select related entities from, with the drop down list returning an ID as its value. <%=Html.DropDownListFor(m => m.Entity.ID)%> When the request is sent the form value is named as expected: "Entity.ID", however my strongly typed Model defined as an action parameter doesn't have Entity.ID populated with the value passed in the request. public ActionResult AddEntity(EntityWithChildEntities entityWithChildEntities) { } I tried fiddling around with the Bind() attribute and specified Bind(Include = "Entity.ID") on the entityWithChildEntities, but that doesn't seem to work. I also tried Bind(Include = "Entity"), but that resulted in the ModelBinder attempting to bind a full "Entity" definition (not surprisingly). Is there any way to get the default model binder to fill the child entity ID or will I need to add action parameters for each child entity's ID and then manually copy the values into the model definition?

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  • When memory is actually freeded?

    - by zhyk
    Hello all. I'm trying to understand memory management stuff in Objective-C. If I see the memory usage listed by Activity Monitor, it looks like memory is not being freed (I mean column rsize). But in "Object Allocations" everything looks fine. Here is my simple code: #import <Foundation/Foundation.h> int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSInteger i, k=10000; while (k>0) { NSMutableArray *array = [[NSMutableArray alloc]init]; for (i=0;i<1000*k; i++) { NSString *srtring = [[NSString alloc] initWithString:@"string...."]; [array addObject:srtring]; [srtring release]; srtring = nil; } [array release]; array = nil; k-=500; } [NSThread sleepForTimeInterval:5]; [pool release]; return 0; } As for retain and release it's cool, everything is balanced. But rsize decreases only after quitting from this little program. Is it possible to "clean" memory somehow before quitting?

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  • Shared Memory and Process Sempahores (IPC)

    - by fsdfa
    This is an extract from Advanced Liniux Programming: Semaphores continue to exist even after all processes using them have terminated. The last process to use a semaphore set must explicitly remove it to ensure that the operating system does not run out of semaphores.To do so, invoke semctl with the semaphore identifier, the number of semaphores in the set, IPC_RMID as the third argument, and any union semun value as the fourth argument (which is ignored).The effective user ID of the calling process must match that of the semaphore’s allocator (or the caller must be root). Unlike shared memory segments, removing a semaphore set causes Linux to deallocate immediately. If a process allocate a shared memory, and many process use it and never set to delete it (with shmctl), if all them terminate, then the shared page continues being available. (We can see this with ipcs). If some process did the shmctl, then when the last process deattached, then the system will deallocate the shared memory. So far so good (I guess, if not, correct me). What I dont understand from that quote I did, is that first it say: "Semaphores continue to exist even after all processes using them have terminated." and then: "Unlike shared memory segments, removing a semaphore set causes Linux to deallocate immediately."

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  • C when to allocate and free memory - before function call, after function call...etc

    - by Keith P
    I am working with my first straight C project, and it has been a while since I worked on C++ for that matter. So the whole memory management is a bit fuzzy. I have a function that I created that will validate some input. In the simple sample below, it just ignores spaces: int validate_input(const char *input_line, char* out_value){ int ret_val = 0; /*false*/ int length = strlen(input_line); cout << "length = " << length << "\n"; out_value =(char*) malloc(sizeof(char) * length + 1); if (0 != length){ int number_found = 0; for (int x = 0; x < length; x++){ if (input_line[x] != ' '){ /*ignore space*/ /*get the character*/ out_value[number_found] = input_line[x]; number_found++; /*increment counter*/ } } out_value[number_found + 1] = '\0'; ret_val = 1; } return ret_val; } Instead of allocating memory inside the function for out_value, should I do it before I call the function and always expect the caller to allocate memory before passing into the function? As a rule of thumb, should any memory allocated inside of a function be always freed before the function returns?

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  • Intel MKL memory management and exceptions

    - by Andrew
    Hello everyone, I am trying out Intel MKL and it appears that they have their own memory management (C-style). They suggest using their MKL_malloc/MKL_free pairs for vectors and matrices and I do not know what is a good way to handle it. One of the reasons for that is that memory-alignment is recommended to be at least 16-byte and with these routines it is specified explicitly. I used to rely on auto_ptr and boost::smart_ptr a lot to forget about memory clean-ups. How can I write an exception-safe program with MKL memory management or should I just use regular auto_ptr's and not bother? Thanks in advance. EDIT http://software.intel.com/sites/products/documentation/hpc/mkl/win/index.htm this link may explain why I brought up the question UPDATE I used an idea from the answer below for allocator. This is what I have now: template <typename T, size_t TALIGN=16, size_t TBLOCK=4> class aligned_allocator : public std::allocator<T> { public: pointer allocate(size_type n, const void *hint) { pointer p = NULL; size_t count = sizeof(T) * n; size_t count_left = count % TBLOCK; if( count_left != 0 ) count += TBLOCK - count_left; if ( !hint ) p = reinterpret_cast<pointer>(MKL_malloc (count,TALIGN)); else p = reinterpret_cast<pointer>(MKL_realloc((void*)hint,count,TALIGN)); return p; } void deallocate(pointer p, size_type n){ MKL_free(p); } }; If anybody has any suggestions, feel free to make it better.

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  • Pagination in a Rich Domain Model

    - by user246790
    I use rich domain model in my app. The basic ideas were taken there. For example I have User and Comment entities. They are defined as following: <?php class Model_User extends Model_Abstract { public function getComments() { /** * @var Model_Mapper_Db_Comment */ $mapper = $this->getMapper(); $commentsBlob = $mapper->getUserComments($this->getId()); return new Model_Collection_Comments($commentsBlob); } } class Model_Mapper_Db_Comment extends Model_Mapper_Db_Abstract { const TABLE_NAME = 'comments'; protected $_mapperTableName = self::TABLE_NAME; public function getUserComments($user_id) { $commentsBlob = $this->_getTable()->fetchAllByUserId((int)$user_id); return $commentsBlob->toArray(); } } class Model_Comment extends Model_Abstract { } ?> Mapper's getUserComments function simply returns something like: return $this->getTable->fetchAllByUserId($user_id) which is array. fetchAllByUserId accepts $count and $offset params, but I don't know to pass them from my Controller to this function through model without rewriting all the model code. So the question is how can I organize pagination through model data (getComments). Is there a "beatiful" method to get comments from 5 to 10, not all, as getComments returns by default.

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  • Formating a table date field from the Model in Codeigniter

    - by Landitus
    Hi, I', trying to re-format a date from a table in Codeigniter. The Controller is for a blog. I was succesfull when the date conversion happens in the View. I was hoping to convert the date in the Model to have things in order. Here's the date conversion as it happens in the View. This is inside the posts loop: <?php foreach($records as $row) : ?> <?php $fdate = "%d <abbr>%M</abbr> %Y"; $dateConv = mdate($fdate, mysql_to_unix($row->date)); ?> <div class="article section"> <span class="date"><?php echo $dateConv ;?></span> ... Keeps going ... This is the Model: class Novedades_model extends Model { function getAll() { $this->db->order_by('date','desc'); $query = $this->db->get('novedades'); if($query->num_rows() > 0) { foreach ($query->result() as $row) { $data[] = $row; } } return $data; } } How can I convert the date in the Model? Can I access the date key and refactor it?

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