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  • Setting the default stack size on Linux globally for the program

    - by wowus
    So I've noticed that the default stack size for threads on linux is 8MB (if I'm wrong, PLEASE correct me), and, incidentally, 1MB on Windows. This is quite bad for my application, as on a 4-core processor that means 64 MB is space is used JUST for threads! The worst part is, I'm never using more than 100kb of stack per thread (I abuse the heap a LOT ;)). My solution right now is to limit the stack size of threads. However, I have no idea how to do this portably. Just for context, I'm using Boost.Thread for my threading needs. I'm okay with a little bit of #ifdef hell, but I'd like to know how to do it easily first. Basically, I want something like this (where windows_* is linked on windows builds, and posix_* is linked under linux builds) // windows_stack_limiter.c int limit_stack_size() { // Windows impl. return 0; } // posix_stack_limiter.c int limit_stack_size() { // Linux impl. return 0; } // stack_limiter.cpp int limit_stack_size(); static volatile int placeholder = limit_stack_size(); How do I flesh out those functions? Or, alternatively, am I just doing this entirely wrong? Remember I have no control over the actual thread creation (no new params to CreateThread on Windows), as I'm using Boost.Thread.

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  • Linux network stack : adding protocols with an LKM and dev_add_pack

    - by agent0range
    Hello, I have recently been trying to familiarize myself with the Linux Networking stack and device drivers (have both similarly named O'Reilly books) with the eventual goal of offloading UDP. I have already implemented UDP on the NIC but now the hard part... Rather than ask for assistance on this larger goal I was hoping someone could clarify for me a particular snippet I found that is part of a LKM which registeres a new protocol (OTP) that acts as a filter between the device driver and network stack. http://www.phrack.org/archives/55/p55_0x0c_Building%20Into%20The%20Linux%20Network%20Layer_by_lifeline%20&%20kossak.txt (Note: this Phrack article contains three different modules, code for the OTP is at the bottom of the page) In the init function of his example he has: otp_proto.type = htons(ETH_P_ALL); otp_proto.func = otp_func; dev_add_pack(&otp_proto); which (if I understand correctly) should register otp_proto as a packet sniffer and put it into the ptype_all data structure. My question is about the dev_add_pack. Is it the case that the protocol being registered as a filter will always be placed at this layer between L2 and the device driver? Or, for instance could I make such a filtering occur between the application and transport layers (analyze socket parameters) using the same process? I apologize if this is confusing - I am having some trouble wrapping my head around the bigger picture when it comes to modules altering kernel stack functionality. Thanks

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  • Struts2 Value Stack

    - by vipul12389
    I want to understand Struts 2 value stack vs request scope. I want the struts2 value stack to work same as request scope. for e.g. i have invoked action1 in struts 2, the action performs some db task and gets back. it performs some operation on a object called cases (type Cases, where Cases is bean class with getters and setters). cases object is declared at class level. action1 led a view to be rendered say jsp1. jsp1 again has some action called as action2. action2 leads to the same java file as of action1 but has different method. Now, i want to access the object which was used in action1. during action1 cases was pushed to Value Stack and was accessed on jsp1. I simply tried accessing its getter methods, but it returns a null value....!! any solution on how to do ??? or is it possible ?? i know if its possible then what is the difference between vs and request scope...

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  • Performance issues when using SSD for a developer notebook (WAMP/LAMP stack)?

    - by András Szepesházi
    I'm a web application developer using my notebook as a standalone development environment (WAMP stack). I just switched from a Core2-duo Vista 32 bit notebook with 2Gb RAM and SATA HDD, to an i5-2520M Win7 64 bit with 4Gb RAM and 128 GB SDD (Corsair P3 128). My initial experience was what I expected, fast boot, quick load of all the applications (Eclipse takes now 5 seconds as opposed to 30s on my old notebook), overall great experience. Then I started to build up my development stack, both as LAMP (using VirtualBox with a debian guest) and WAMP (windows native apache + mysql + php). I wanted to compare those two. This still all worked great out, then I started to pull in my projects to these stacks. And here came the nasty surprise, one of those projects produced a lot worse response times than on my old notebook (that was true for both the VirtualBox and WAMP stack). Apache, php and mysql configurations were practically identical in all environments. I started to do a lot of benchmarking and profiling, and here is what I've found: All general benchmarks (Performance Test 7.0, HDTune Pro, wPrime2 and some more) gave a big advantage to the new notebook. Nothing surprising here. Disc specific tests showed that read/write operations peaked around 380M/160M for the SSD, and all the different sized block operations also performed very well. Started apache performance benchmarking with Apache Benchmark for a small static html file (10 concurrent threads, 500 iterations). Old notebook: min 47ms, median 111ms, max 156ms New WAMP stack: min 71ms, median 135ms, max 296ms New LAMP stack (in VirtualBox): min 6ms, median 46ms, max 175ms Right here I don't get why the native WAMP stack performed so bad, but at least the LAMP environment brought the expected speed. Apache performance measurement for non-cached php content. The php runs a loop of 1000 and generates sha1(uniqid()) inisde. Again, 10 concurrent threads, 500 iterations were used for the benchmark. Old notebook: min 0ms, median 39ms, max 218ms New WAMP stack: min 20ms, median 61ms, max 186ms New LAMP stack (in VirtualBox): min 124ms, median 704ms, max 2463ms What the hell? The new LAMP performed miserably, and even the new native WAMP was outperformed by the old notebook. php + mysql test. The test consists of connecting to a database and reading a single record form a table using INNER JOIN on 3 more (indexed) tables, repeated 100 times within a loop. Databases were identical. 10 concurrent threads, 100 iterations were used for the benchmark. Old notebook: min 1201ms, median 1734ms, max 3728ms New WAMP stack: min 367ms, median 675ms, max 1893ms New LAMP stack (in VirtualBox): min 1410ms, median 3659ms, max 5045ms And the same test with concurrency set to 1 (instead of 10): Old notebook: min 1201ms, median 1261ms, max 1357ms New WAMP stack: min 399ms, median 483ms, max 539ms New LAMP stack (in VirtualBox): min 285ms, median 348ms, max 444ms Strictly for my purposes, as I'm using a self contained development environment (= low concurrency) I could be satisfied with the second test's result. Though I have no idea why the VirtualBox environment performed so bad with higher concurrency. Finally I performed a test of including many php files. The application that I mentioned at the beginning, the one that was performing so bad, has a heavy bootstrap, loads hundreds of small library and configuration files while initializing. So this test does nothing else just includes about 100 files. Concurrency set to 1, 100 iterations: Old notebook: min 140ms, median 168ms, max 406ms New WAMP stack: min 434ms, median 488ms, max 604ms New LAMP stack (in VirtualBox): min 413ms, median 1040ms, max 1921ms Even if I consider that VirtualBox reached those files via shared folders, and that slows things down a bit, I still don't see how could the old notebook outperform so heavily both new configurations. And I think this is the real root of the slow performance, as the application uses even more includes, and the whole bootstrap will occur several times within a page request (for each ajax call, for example). To sum it up, here I am with a brand new high-performance notebook that loads the same page in 20 seconds, that my old notebook can do in 5-7 seconds. Needless to say, I'm not a very happy person right now. Why do you think I experience these poor performance values? What are my options to remedy this situation?

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  • Stack Overflow problem in a recursive program in C

    - by Adi
    Hi all, I am getting a stack overflow in one of the recursive functions i am running.. Here is the code.. void* buddyMalloc(int req_size) { // Do something here return buddy_findout(original_index,req_size); // This is the recursive call } void *buddy_findout(int current_index,int req_size) { char *selected = NULL; if(front!=NULL) { if(current_index==original_index) { // Do something here return selected; } else { // Do Something here return buddy_findout(current_index+1,req_size); } } else { return buddy_findout(current_index-1,req_size); } } Consider the initial value of index to be 4. and it first do index-1 till it reaches 0 index. and then it comes back to index 4 by incrementing..This is wht i want to implement. But it gives a stack overflow with memory map in the command prompt : Here is the output from my shell : * glibc detected * ./473_mem: free(): invalid pointer: 0x00c274c0 * ======= Backtrace: ========= /lib/tls/i686/cmov/libc.so.6[0xb50ff1] /lib/tls/i686/cmov/libc.so.6[0xb526f2] /lib/tls/i686/cmov/libc.so.6(cfree+0x6d)[0xb557cd] ./473_mem[0x8048b44] ./473_mem[0x8048b74] ./473_mem[0x8048b74] ./473_mem[0x8048944] ./473_mem[0x8048c87] ./473_mem[0x8048d31] ./473_mem[0x8048f79] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe6)[0xafcb56] ./473_mem[0x8048671] ======= Memory map: ======== 0017c000-00198000 r-xp 00000000 08:01 5224 /lib/libgcc_s.so.1 00198000-00199000 r--p 0001b000 08:01 5224 /lib/libgcc_s.so.1 00199000-0019a000 rw-p 0001c000 08:01 5224 /lib/libgcc_s.so.1 00260000-00284000 r-xp 00000000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 00284000-00285000 r--p 00023000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 00285000-00286000 rw-p 00024000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 006cd000-006e8000 r-xp 00000000 08:01 6662 /lib/ld-2.10.1.so 006e8000-006e9000 r--p 0001a000 08:01 6662 /lib/ld-2.10.1.so 006e9000-006ea000 rw-p 0001b000 08:01 6662 /lib/ld-2.10.1.so 00aa9000-00aaa000 r-xp 00000000 00:00 0 [vdso] 00ae6000-00c24000 r-xp 00000000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c24000-00c25000 ---p 0013e000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c25000-00c27000 r--p 0013e000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c27000-00c28000 rw-p 00140000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c28000-00c2b000 rw-p 00000000 00:00 0 08048000-0804a000 r-xp 00000000 00:14 2176 /media/windows-share/OS/Project2/473_mem 0804a000-0804b000 r--p 00001000 00:14 2176 /media/windows-share/OS/Project2/473_mem 0804b000-0804c000 rw-p 00002000 00:14 2176 /media/windows-share/OS/Project2/473_mem 08483000-084a4000 rw-p 00000000 00:00 0 [heap] b7600000-b7621000 rw-p 00000000 00:00 0 b7621000-b7700000 ---p 00000000 00:00 0 b7716000-b7819000 rw-p 00000000 00:00 0 b7827000-b782a000 rw-p 00000000 00:00 0 bfb96000-bfbab000 rw-p 00000000 00:00 0 [stack] Aborted Thanks in advance adi

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  • Android - Calling getJSONArray throwing JSONException with no stack trace

    - by Agathron
    Hi all, I'm currently working on an android app that pulls a list of forums from a JSON feed. I'm trying to parse the feed and immediately upon calling getJSONArray a JSON exception is being thrown with no stack trace. The JSON being returned is stored in an JSONObject jobj with the format as follows: { "Forum": [ {"ForumName":"CEC Employee Communications Forum","ForumId":"105"}, {"ForumName":"CEC External Stakeholder Relations Forum","ForumId":"109"}, {"ForumName":"See All...","ForumId":"0"} ] } However when running the following code, I get an immediate exception without a stack trace: JSONArray jarray = new JSONArray(); jarray = jobj.getJSONArray("Forum"); Running jobj.GetJSONArray("Forum").toString(); returns what looks to be a correct array of the format: [ {"ForumName":"CEC Employee Communications Forum","ForumId":"105"}, {"ForumName":"CEC External Stakeholder Relations Forum","ForumId":"109"}, {"ForumName":"See All...","ForumId":"0"} ] I also tried JSONArray jarray = new JSONArray(jobj.GetJSONArray("Forum").toString()); and had the exception thrown immediately. Any help would be greatly appreciated. Thanks!

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  • XCode 3.2.1 and Instruments: Useless Stack Trace

    - by Jason George
    I've reached the stage where it's time to start tracking down memory leaks and, to my dismay, Instruments is giving me very little to go on (other than the fact that I definitely have leaks). My stack trace contains no information other than memory addresses. Since I'm working on a new project and I've transitioned to version 3.2.1 of XCode in tandem, I'm not sure if it's my program configuration or XCode that's causing the problem. I have found one reference to the issue coupled with a post on the dyld leak that seems to be prevalent with the 3.2.1 release. Since I haven't been able to find much on the problem I'm guessing it's something I've created rather than a systematic issue with XCode. If someone has any idea where I might have thrown a wrench in the works, I would love some pointers. Also, if someone could just verify that the stack trace is indeed functioning properly in 3.2.1 that would be useful as well.

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  • OpenID like Stack Overflow

    - by eWolf
    I want to create an OpenID login with PHP just like it can be found on Stack Overflow. I know there are many questions for this, but mine is different. If I understood it correctly, every OpenID is defined by a unique URL. But: If I hit the Google button on the Stack Overflow login page, one generic URL is inserted in the text field. Is this the direct URL to the OpenID server? And if it is, how do I have to pass the URL to this class?

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  • How does a virtual machine work?

    - by Martin
    I've been looking into how programming languages work, and some of them have a so-called virtual machines. I understand that this is some form of emulation of the programming language within another programming language, and that it works like how a compiled language would be executed, with a stack. Did I get that right? With the proviso that I did, what bamboozles me is that many non-compiled languages allow variables with "liberal" type systems. In Python for example, I can write this: x = "Hello world!" x = 2**1000 Strings and big integers are completely unrelated and occupy different amounts of space in memory, so how can this code even be represented in a stack-based environment? What exactly happens here? Is x pointed to a new place on the stack and the old string data left unreferenced? Do these languages not use a stack? If not, how do they represent variables internally?

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  • Assembly stack persistency

    - by user246100
    Hello. I would like to know if after calling functions the data I have in the stack is persistent. Like, I would like to know if (assuming cdecl convention) can I do this (independently of function X and independently of optimizations): push 1 push 2 push 3 call X call X call X add 12 esp ? Also, let's say that before the calls I save the address of where the pushed values are in a global variable. Can I, inside X, alter the values it contain by acessing the global variable? Like, for some reason I want that in X I'm able to alter the values in stack so that the second and third call to X receive different values.

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  • setting up/installing/configuring nginx LEMP stack on fresh VPS server

    - by grant tailor
    I need some help in settingup/installing and configuring nginx LEMP stack on a fresh new VPS i have. The specs of the CentOS 5.7 VPS are 2GB DDR3 ECC RAM(4GB burst), 1 core 1.5Ghz(3Ghz burst) and 100GB RAID 10 storage, unmetered bandwidth @ 100Mpbs all for a whopping $25/month(unbeatable, yeah i know :) Anyways i have followed this LEMP(will also need MySQL and PHP) stack guide on linode http://library.linode.com/lemp-guides/centos-5 but basically what i want is to be able to host multiple website on this webserver after everything is setup. I am used to using DirectAdmin control panel on other server and want to have things setup so i can host multiple websites...mostly wordpress and drupal themes. Lets say 10 websites on this nginx web server. So can someone please help me on what i need to do to take "full" advantage of nginx power and performance, while been able to easily manage these multiple websites (wordpress and drupal themes)? Thanks.

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  • StackOverflowException in c# when no local variable in the function

    - by dnkulkarni
    when i do this static void Main() { Main(); } I receive stackoverflow exception. As i have read so far about C# they say ONLY local variable of value types (and short living ones) will go on stack. But here in the code there are no local variable to go on stack then what overflows it ? I know from assembly code line Perspective that reference to Main() will go on stack too ? Is that right ?

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  • Stack trace in website project, when debug = false

    - by chandmk
    We have a website project. We are logging unhanded exceptions via a appdomain level exception handler. When we set debug= true in web.config, the exception log is showing the offending line numbers in the stack trace. But when we set debug = false, in web.config, log is not displaying the line numbers. We are not in a position to convert the website project in to webapplication project type at this time. Its legacy application and almost all the code is in aspx pages. We also need to leave the project in 'updatable' mode. i.e. We can't user pre-compile option. We are generating pdb files. Is there anyway to tell this kind of website projects to generate the pdb files, and show the line numbers in the stack trace?

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  • A very basic auto-expanding list/array

    - by MainMa
    Hi, I have a method which returns an array of fixed type objects (let's say MyObject). The method creates a new empty Stack<MyObject>. Then, it does some work and pushes some number of MyObjects to the end of the Stack. Finally, it returns the Stack.ToArray(). It does not change already added items or their properties, nor remove them. The number of elements to add will cost performance. There is no need to sort/order the elements. Is Stack a best thing to use? Or must I switch to Collection or List to ensure better performance and/or lower memory cost?

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  • Changing the background colour of lines in the stack

    - by Mongus Pong
    I have just changed the colour scheme of my Visual Studio 2008 environment to have a dark backround with light text. This is so much easier on the eyes. The only problem is lines that are on the call stack... Those lines that are referred to in this thread here in visual studio some lines of code have light grey background while debugging These lines have a bright grey background, which against my light text means I cannot read the text at all. I have been through every single colour in Tools - Options - Fonts and Colours and cannot find one that matches. How can I change the background for lines on the current call stack?

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  • OutOfMemoryException, stack size is huge, large number of threads

    - by Captain Comic
    Hello, I was profiling my .net windows service. I was trying to discover OutOfMemoryException and discovered that my stack size is huge and is growing because the the number of threads keeps growing. Each thread gets 1024 KB on Windows x64 machine. Thus when my app has 754 threads the stack size would be 772 MB. The problem for me is that i don't know where these thread come from. Initially my app has a very limited number of threads and they keep growing with time. I have two suspicions - either these threads are created by WCF or by database connection. My application uses both WCF and datasets. Also I tried to profile my app in Ants do Trace i can see large number of System.ServiceModel.Channels.ClientReliableDuplexSessionChannel and this number is increasing with time. I can see thousands of these objects created. So what I want to know is who is creating threads (tools to discover, profilers) and if it is WCF who is creating these threads.

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  • How to implement three stacks using a single array.

    - by buried-shopno
    Hi, I came across this problem in an interview website. The problem asks for efficiently implement three stacks in a single array, such that no stack overflows until there is no space left in the entire array space. For implementing 2 stacks in an array, it's pretty obvious: 1st stack grows from LEFT to RIGHT, and 2nd stack grows from RIGHT to LEFT; and when the stackTopIndex crosses, it signals an overflow. Thanks in advance for your insightful answer.

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  • Recursive function causing a stack overflow

    - by dbyrne
    I am trying to write a simple sieve function to calculate prime numbers in clojure. I've seen this question about writing an efficient sieve function, but I am not to that point yet. Right now I am just trying to write a very simple (and slow) sieve. Here is what I have come up with: (defn sieve [potentials primes] (if-let [p (first potentials)] (recur (filter #(not= (mod % p) 0) potentials) (conj primes p)) primes)) For small ranges it works fine, but causes a stack overflow for large ranges: user=> (sieve (range 2 30) []) [2 3 5 7 11 13 17 19 23 29] user=> (sieve (range 2 15000) []) java.lang.StackOverflowError (NO_SOURCE_FILE:0) I thought that by using recur this would be a non-stack-consuming looping construct? What am I missing?

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  • Manual stack backtrace on Windows mobile (SEH)

    - by caahab
    Following situation: I'm developing an windows mobile application using the sdk 6. Target machine is a nautiz x7. To improve the error reporting I want to catch the structured exceptions (SEH) and do a stack backtrace to store some information for analysis. So far I have the information where the exception was thrown (windows core.dll) and I can backtrace the return adresses thru the stack. But what I want to know is, which instruction in my code caused the exception? Does anyone know how to use the available exception and context information to get the appropriate function/instruction address? Unfortunately windows mobile 6 sdk for pocketpc does not support all the helper functions to do stackwalks or mini dumps.

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  • Is this implementation truely tail-recursive?

    - by CFP
    Hello everyone! I've come up with the following code to compute in a tail-recursive way the result of an expression such as 3 4 * 1 + cos 8 * (aka 8*cos(1+(3*4))) The code is in OCaml. I'm using a list refto emulate a stack. type token = Num of float | Fun of (float->float) | Op of (float->float->float);; let pop l = let top = (List.hd !l) in l := List.tl (!l); top;; let push x l = l := (x::!l);; let empty l = (l = []);; let pile = ref [];; let eval data = let stack = ref data in let rec _eval cont = match (pop stack) with | Num(n) -> cont n; | Fun(f) -> _eval (fun x -> cont (f x)); | Op(op) -> _eval (fun x -> cont (op x (_eval (fun y->y)))); in _eval (fun x->x) ;; eval [Fun(fun x -> x**2.); Op(fun x y -> x+.y); Num(1.); Num(3.)];; I've used continuations to ensure tail-recursion, but since my stack implements some sort of a tree, and therefore provides quite a bad interface to what should be handled as a disjoint union type, the call to my function to evaluate the left branch with an identity continuation somehow irks a little. Yet it's working perfectly, but I have the feeling than in calling the _eval (fun y->y) bit, there must be something wrong happening, since it doesn't seem that this call can replace the previous one in the stack structure... Am I misunderstanding something here? I mean, I understand that with only the first call to _eval there wouldn't be any problem optimizing the calls, but here it seems to me that evaluation the _eval (fun y->y) will require to be stacked up, and therefore will fill the stack, possibly leading to an overflow... Thanks!

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