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  • Heap data structure

    - by turmoil
    Trying to think of a lower bound to the position of say, the nth largest key in a max-heap. Assuming the heap's laid out in array. The upper bound's min(2^n-2, array size -1) i think, but is it always lower bounded by 0?

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  • When to address managed heap fragmentation

    - by emddudley
    I was reading a blog entry by Josh Smith where he used a cache mechanism in order to "reduce managed heap fragmentation". His caching reduces the number of short-lived objects being created at the cost of slightly slower execution speed. How much of a problem is managed heap fragmentation in a managed language like C#? How can you diagnose if it's an issue? In what situations would you typically need to address it?

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  • Heap Consistency Checking on Embedded System

    - by l.thee.a
    I get a crash like this: #0 0x2c58def0 in raise () from /lib/libpthread.so.0 #1 0x2d9b8958 in abort () from /lib/libc.so.0 #2 0x2d9b7e34 in __malloc_consolidate () from /lib/libc.so.0 #3 0x2d9b6dc8 in malloc () from /lib/libc.so.0 I guess it is a heap corruption issue. uclibc does not have mcheck/mprobe. Valgrind does not seem to MIPS support and my app (which is multi-threaded) depends on hw specific drivers. Any suggestions to check the consistency of the heap and to detect corruption?

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  • Understanding max JVM heap size

    - by Marcus
    I've read the max heap size on 32bit Windows is ~1.5GB which is due to the fact that the JVM requires contiguous memory. Can someone explain the concept of "contiguous memory" and why you only have max 1.5GB on Windows? Secondly, what then is the max heap size on 64 bit Windows and why is this different than what's available on 32 bit?

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  • How do I compare binary files in Linux?

    - by frustratedCmpNoLongerUser
    I need to compare two binary files and get the output in the form <fileoffset-hex <file1-byte-hex <file2-byte-hex for every different byte. So if file1.bin is 00 90 00 11 in binary form and file2.bin is 00 91 00 10 I want to get something like 00000001 90 91 00000003 11 10 What is the easiest way to accomplish the goal? Standard tool? Some third-party tool? (Note: cmp -l should be killed with fire, it uses a decimal system for offsets and octal for bytes.)

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  • Odd FTP ASCII/BINARY transfer behavior after migrating to a new server

    - by Incognita Mundi
    I recently got a dedicated server and after migration to the new machine I started noticing problems with file transfers. My FTP client, despite being set to auto, keeps uploading php files in binary mode and the content of those files is messed up. Since I mostly upload files of different kinds it would be annoying to change from binary to ASCII every single time, beside, I never had such problems. What could be the cause of this behavior? My dedicated server runs CENTOS 6.4 and the ftp server is Pure-FTPd. I tried different FTP clients and they all have the same problem so I assume is soem misconfiguration on the server side. Thanks

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  • stack and heap issue for iPhone memory management

    - by Forrest
    From this post I got know that the Objective-C runtime does not allow objects to be instantiated on the stack, but only on the heap; this means that you don’t have “automatic objects”, nor things like auto_ptr objects to help you manage memory; Someone give one example in post Objective C: Memory Allocation on stack vs. heap NSString* str = @"hello"; but this NSString is also not allocated in stack. Feel odd that this str is static. (Who can explain this ? ) Question here is that why there is no heap ? even mixing c++ together with Object C ? /////////////////////////////// Clear my question /////////////////////////////// I am confused , so questions are not clear. Let me put in this way. 1) All Object C objects should be alloc in stack ? ( I think yes ) 2)In C++, there are stack for memory, so for iOS app, also have stack ? ( I think yes ) 3) for iOS app, if only use Object C, so what is the usage of stack ? what kind of objects should use stack then ?

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  • Heap Algorithmic Issue

    - by OberynMarDELL
    I am having this algorithmic problem that I want to discuss about. Its not about find a solution but about optimization in terms of runtime. So here it is: Suppose we have a race court of Length L and a total of N cars that participate on the race. The race rules are simple. Once a car overtakes an other car the second car is eliminated from the race. The race ends when no more overtakes are possible to happen. The tricky part is that the k'th car has a starting point x[k] and a velocity v[k]. The points are given in an ascending order, but the velocities may differ. What I've done so far: Given that a car can get overtaken only by its previous, I calculated the time that it takes for each car to reach its next one t = (x[i] - x[i+1])/(v[i] - v[i+1]) and I insert these times onto a min heap in O(n log n). So in theory I have to pop the first element in O(logn), find its previous, pop it as well , update its time and insert it in the heap once more, much like a priority queue. My main problem is how I can access specific points of a heap in O(log n) or faster in order to keep the complexity in O(n log n) levels. This program should be written on Haskell so I would like to keep things simple as far as possible EDIT: I Forgot to write the actual point of the race. The goal is to find the order in which cars exit the game

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  • Embedding binary blobs using gcc mingw

    - by myforwik
    I am trying to embed binary blobs into an exe file. I am using mingw gcc. I make the object file like this: ld -r -b binary -o binary.o input.txt I then look objdump output to get the symbols: objdump -x binary.o And it gives symbols named: _binary_input_txt_start _binary_input_txt_end _binary_input_txt_size I then try and access them in my C program: #include <stdlib.h> #include <stdio.h> extern char _binary_input_txt_start[]; int main (int argc, char *argv[]) { char *p; p = _binary_input_txt_start; return 0; } Then I compile like this: gcc -o test.exe test.c binary.o But I always get: undefined reference to _binary_input_txt_start Does anyone know what I am doing wrong?

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  • How to tell binary from text files in linux

    - by gabor
    The linux file command does a very good job in recognising file types and gives very fine-grained results. The diff tool is able to tell binary files from text files, producing a different output. Is there a way to tell binary files form text files? All I want is a yes/no answer whether a given file is binary. Because it's difficult to define binary, let's say I want to know if diff will attempt a text-based comparison. To clarify the question: I do not care if it's ASCII text or XML as long as it's text. Also, I do not want to differentiate between MP3 and JPEG files, as they're all binary.

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  • How to redistribute binary programs built on modern Ubuntu so that they can be executed on any older Linux system ?

    - by psihodelia
    I found that if I build any binary on Ubuntu 10.10, then it doesn't execute on some older Linuxes. It is because Ubuntu uses a very new C library, called EGLIBC. Most of the desktop Linux systems use GLIBC. I would like to know whether there is any standard method how to redistribute binary programs built on a modern Ubuntu so that they can be executed on any older Linux system ? How to find all required dependencies (glibc version, dynamic libraries) ?

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  • Error importing large MySQL dump file which includes binary BLOBs in Windows

    - by Daniel Magliola
    I'm trying to import a MySQL dump file, which I got from my hosting company, into my Windows dev machine, and i'm running into problems. I'm importing this from the command line, and i'm getting a very weird error: ERROR 2005 (HY000) at line 3118: Unknown MySQL server host '+?*á±dÆ-N+Æ·h^ye"p-i+ Z+-$?P+Y.8+|?+l8/l¦¦î7æ¦X¦XE.ºG[ ;-ï?éµ?º+¦¦].?+f9d릦'+ÿG?-0à¡úè?-?ù??¥'+NÑ' (11004) I'm attaching the screenshot because i'm assuming the binary data will get lost... I'm not exactly sure what the problem is, but two potential issues are the size of the file (2 Gb) which is not insanely large, but it's not trivially small either, and the other is the fact that many of these tables have JPG images in them (which is why the file is 2Gb large, for the most part). Also, the dump was taken in a Linux machine and I'm importing this into Windows, not sure if that could add to the problems (I understand it shouldn't) Now, that binary garbage is why I think the images in the file might be a problem, but i've been able to import similar dumps from the same hosting company in the past, so i'm not sure what might be the issue. Also, trying to look into this file (and line 3118 in particular) is kind of impossible given its size (i'm not really handy with Linux command line tools like grep, sed, etc). The file might be corrupted, but i'm not exactly sure how to check it. What I downloaded was a .gz file, which I "tested" with WinRar and it says it looks OK (i'm assuming gz has some kind of CRC). If you can think of a better way to test it, I'd love to try that. Any ideas what could be going on / how to get past this error? I'm not very attached to the data in particular, since I just want this as a copy for dev, so if I have to lose a few records, i'm fine with that, as long as the schema remains perfectly sound. Thanks! Daniel

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  • Getting Out Of Memory: Java heap space, but while viewing heap space it max uses 50 MB

    - by ikky
    Hi! I'm using ASANT to run a xml file which points to a NARS.jar file. (i do not have the project file of the NARS.jar) I'm getting "java.lang.OutOfMemoryError: Java heap space. I used VisualVM to look at the heap while running the NARS.jar, and it says that it max uses 50 MB of the heapspace. I've set the initial and max size of heapspace to 512 MB. Does anyone have an ide of what could be wrong? I got 1 GB physical Memory and created a 5 GB pagefile (for test purpose). Thanks in advance.

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  • Java Heap Overflow, Forcing Garbage Collection

    - by Nicholas
    I've create a trie tree with an array of children. When deleting a word, I set the children null, which I would assume deletes the node(delete is a relative term). I know that null doesn't delete the child, just sets it to null, which when using a large amount of words it causes to overflow the heap. Running a top on linux, I can see my memory usage spike to 1gb pretty quickly, but if I force garbage collection after the delete (Runtime.gc()) the memory usage goes to 50mb and never above that. From what I'm told, java by default runs garbage collection before a heap overflow happens, but I can't see to make that happen.

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  • Class members allocation on heap/stack? C++

    - by simplebutperfect
    If a class is declared as follows: class MyClass { char * MyMember; MyClass() { MyMember = new char[250]; } ~MyClass() { delete[] MyMember; } }; And it could be done like this: class MyClass { char MyMember[250]; }; How does a class gets allocated on heap, like if i do MyClass * Mine = new MyClass(); Does the allocated memory also allocates the 250 bytes in the second example along with the class instantiation? And will the member be valid for the whole lifetime of MyClass object? As for the first example, is it practical to allocate class members on heap?

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  • How to increase Java heap space for a tomcat app

    - by Ankur
    There are lots of questions that ask this or a similar question. They all give the command that has to be executed, what I don't understand is where do I write this command. I want to permanently increase the heap space for my tomcat apps. I read this page http://javahowto.blogspot.com/2006/06/6-common-errors-in-setting-java-heap.html and it says under the Tomcat section Stop Tomcat server, set environment variable CATALINA_OPTS, and then restart Tomcat. Look at the file tomcat-install/bin/catalina.sh or catalina.bat for how this variable is used. For example, set CATALINA_OPTS=-Xms512m -Xmx512m (Windows, no "" around the value) export CATALINA_OPTS="-Xms512m -Xmx512m" (ksh/bash, "" around the value) setenv CATALINA_OPTS "-Xms512m -Xmx512m" (tcsh/csh, "" around the value) So I replaced the line set CATALINA_OPTS= with set CATALINA_OPTS=-Xms512m -Xmx512m But I still get the error.

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  • Pointer-based binary heap implementation

    - by Derek Chiang
    Is it even possible to implement a binary heap using pointers rather than an array? I have searched around the internet (including SO) and no answer can be found. The main problem here is that, how do you keep track of the last pointer? When you insert X into the heap, you place X at the last pointer and then bubble it up. Now, where does the last pointer point to? And also, what happens when you want to remove the root? You exchange the root with the last element, and then bubble the new root down. Now, how do you know what's the new "last element" that you need when you remove root again?

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  • Examining C/C++ Heap memory statistics in gdb

    - by fd
    I'm trying to investigate the state of the C/C++ heap from within gdb on Linux amd64, is there a nice way to do this? One approach I've tried is to "call mallinfo()" but unfortunately I can't then extract the values I want since gdb deal with the return value properly. I'm not easily able to write a function to be compiled into the binary for the process I am attached to, so I can simply implement my own function to extract the values by calling mallinfo() in my own code this way. Is there perhaps a clever trick that will allow me to do this on-the-fly? Another option could be to locate the heap and traverse the malloc headers / free list; I'd appreciate any pointers to where I could start in finding the location and layout of these. I've been trying to Google and read around the problem for about 2 hours and I've learnt some fascinating stuff but still not found what I need.

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  • Is there a way to make PHP's SplHeap recalculate? (aka: add up-heap to SplHeap?)

    - by md2k7
    I am using an SplHeap to hold graph nodes of a tree with directed edges that will be traversed from the leaves to the root. For this, I precalculate the "fan-in" of nodes and put them into the heap so that I can always retrieve the node with the smallest fan-in (0) from it. After visiting a node, I reduce the fan-in of its successor by 1. Then obviously, the heap needs to be recalculated because the successor is now in the wrong place there. I have tried recoverFromCorruption(), but it doesn't do anything and keeps the heap in the wrong order (node with larger fanIn stays in front of smaller fanIn). As a workaround, I'm now creating a new heap after each visit, amounting to a full O(N*log(N)) sort each time. It should be possible, however, to make up-heap operations on the changed heap entry until it's in the right position in O(log(N)). The API for SplHeap doesn't mention an up-heap (or deletion of an arbitrary element - it could then be re-added). Can I somehow derive a class from SplHeap to do this or do I have to create a pure PHP heap from scratch? EDIT: Code example: class VoteGraph { private $nodes = array(); private function calculateFanIn() { /* ... */ } // ... private function calculateWeights() { $this->calculateFanIn(); $fnodes = new GraphNodeHeap(); // heap by fan-in ascending (leaves are first) foreach($this->nodes as $n) { // omitted: filter loops $fnodes->insert($n); } // traversal from leaves to root while($fnodes->valid()) { $node = $fnodes->extract(); // fetch a leaf from the heap $successor = $this->nodes[$node->successor]; // omitted: actual job of traversal $successor->fanIn--; // will need to fix heap (sift up successor) because of this //$fnodes->recoverFromCorruption(); // doesn't work for what I want // workaround: rebuild $fnodes from scratch $fixedHeap = new GraphNodeHeap(); foreach($fnodes as $e) $fixedHeap->insert($e); $fnodes = $fixedHeap; } } } class GraphNodeHeap extends SplHeap { public function compare($a, $b) { if($a->fanIn === $b->fanIn) return 0; else return $a->fanIn < $b->fanIn ? 1 : -1; } }

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  • Maven easyb plugin java heap space settings?

    - by vinnu
    Hi, I attempted to change my heap size for maven easyb plugin http://www.easyb.org/maven-easyb-plugin/. In my easyb test I added standard code to print the heap size using the code Runtime.getFreeMemory() and Runtime.getTotalMemory(). I tried setting the MAVEN_OPTS=-Xmx1024m -Xms1024m and also set the maven opts in Maven surefire plugin. Now when I run the same class from the Junit I can see the getTotalMemory() displaying a number close 1Gig but the when the same classes are invoked from easyb plugin they do not reflect the memory size. Shouldn't there be a way of passing JVM opts to maven easyb plugin when it runs these easyb tests? At the very minimum it should atleast pick up the MAVEN_OPTS settings from the environment. Has someone bumped into problems like this? (A search on this group's archive does not reveal much)

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  • What is the most efficient way to convert to binary and back in C#?

    - by Saad Imran.
    I'm trying to write a general purpose socket server for a game I'm working on. I know I could very well use already built servers like SmartFox and Photon, but I wan't to go through the pain of creating one myself for learning purposes. I've come up with a BSON inspired protocol to convert the the basic data types, their arrays, and a special GSObject to binary and arrange them in a way so that it can be put back together into object form on the client end. At the core, the conversion methods utilize the .Net BitConverter class to convert the basic data types to binary. Anyways, the problem is performance, if I loop 50,000 times and convert my GSObject to binary each time it takes about 5500ms (the resulting byte[] is just 192 bytes per conversion). I think think this would be way too slow for an MMO that sends 5-10 position updates per second with a 1000 concurrent users. Yes, I know it's unlikely that a game will have a 1000 users on at the same time, but like I said earlier this is supposed to be a learning process for me, I want to go out of my way and build something that scales well and can handle at least a few thousand users. So yea, if anyone's aware of other conversion techniques or sees where I'm loosing performance I would appreciate the help. GSBitConverter.cs This is the main conversion class, it adds extension methods to main datatypes to convert to the binary format. It uses the BitConverter class to convert the base types. I've shown only the code to convert integer and integer arrays, but the rest of the method are pretty much replicas of those two, they just overload the type. public static class GSBitConverter { public static byte[] ToGSBinary(this short value) { return BitConverter.GetBytes(value); } public static byte[] ToGSBinary(this IEnumerable<short> value) { List<byte> bytes = new List<byte>(); short length = (short)value.Count(); bytes.AddRange(length.ToGSBinary()); for (int i = 0; i < length; i++) bytes.AddRange(value.ElementAt(i).ToGSBinary()); return bytes.ToArray(); } public static byte[] ToGSBinary(this bool value); public static byte[] ToGSBinary(this IEnumerable<bool> value); public static byte[] ToGSBinary(this IEnumerable<byte> value); public static byte[] ToGSBinary(this int value); public static byte[] ToGSBinary(this IEnumerable<int> value); public static byte[] ToGSBinary(this long value); public static byte[] ToGSBinary(this IEnumerable<long> value); public static byte[] ToGSBinary(this float value); public static byte[] ToGSBinary(this IEnumerable<float> value); public static byte[] ToGSBinary(this double value); public static byte[] ToGSBinary(this IEnumerable<double> value); public static byte[] ToGSBinary(this string value); public static byte[] ToGSBinary(this IEnumerable<string> value); public static string GetHexDump(this IEnumerable<byte> value); } Program.cs Here's the the object that I'm converting to binary in a loop. class Program { static void Main(string[] args) { GSObject obj = new GSObject(); obj.AttachShort("smallInt", 15); obj.AttachInt("medInt", 120700); obj.AttachLong("bigInt", 10900800700); obj.AttachDouble("doubleVal", Math.PI); obj.AttachStringArray("muppetNames", new string[] { "Kermit", "Fozzy", "Piggy", "Animal", "Gonzo" }); GSObject apple = new GSObject(); apple.AttachString("name", "Apple"); apple.AttachString("color", "red"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)1.5); GSObject lemon = new GSObject(); apple.AttachString("name", "Lemon"); apple.AttachString("color", "yellow"); apple.AttachBool("inStock", false); apple.AttachFloat("price", (float)0.8); GSObject apricoat = new GSObject(); apple.AttachString("name", "Apricoat"); apple.AttachString("color", "orange"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)1.9); GSObject kiwi = new GSObject(); apple.AttachString("name", "Kiwi"); apple.AttachString("color", "green"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)2.3); GSArray fruits = new GSArray(); fruits.AddGSObject(apple); fruits.AddGSObject(lemon); fruits.AddGSObject(apricoat); fruits.AddGSObject(kiwi); obj.AttachGSArray("fruits", fruits); Stopwatch w1 = Stopwatch.StartNew(); for (int i = 0; i < 50000; i++) { byte[] b = obj.ToGSBinary(); } w1.Stop(); Console.WriteLine(BitConverter.IsLittleEndian ? "Little Endian" : "Big Endian"); Console.WriteLine(w1.ElapsedMilliseconds + "ms"); } Here's the code for some of my other classes that are used in the code above. Most of it is repetitive. GSObject GSArray GSWrappedObject

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  • Free-as-in-beer binary file format inspector

    - by fbrereto
    I am looking for a utility that gives me the ability to specify a binary file format and then interpret a file of bytes according to that format. (Something along the lines of the 010 Editor, but infinitely more cost-effective). Something that runs on Mac OS X would be preferred, but I'm interested to see what all is out there in general (while more of a hassle I'd be willing to run a tool on Windows if it were superior.) What's your preference?

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