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  • High PageIOLatch_SH Waits with High Drive Idle times

    - by Marty Trenouth
    We are experiencing high volume of PageIOLatch_SH waits on our database (row counts in the Billions). However it seems that our drive Idle time Percentage hovers around 50-60 percent. CPU usage is nill. The Database Tuning Advisor gives no suggestions for optimization. The query plan (actual) from the single stored procedure used on the database puts the majority of the expense on index seek (yeah I know these should be optimial) operations. Anyone have suggestions of how to increase throughput?

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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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  • LNK1106 with big binary resource

    - by E Dominique
    I have a rather huge .dat-file (896MB) included as a BIN resource in my project. Now I get a LNK1106 link error ("fatal error LNK1106: invalid file or disk full: cannot seek to 0x382A3920".) I use Visual Studio 2005 under Windows XP, and have tried on a 4GB RAM machine with high Virtual Memory settings and lots of disk space. I have tried a number of different optimization flags, but to no avail. Does anyone have a clue? EDIT: I have narrowed it down to a specific size of the compiled resource. If the .res file is 544078588 bytes (about 518.9MB) or larger, the error occurs. If it is smaller it works just fine. Still no solution, though...

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  • Backup to disk, encrypted, without any installed local software

    - by user30064
    Hi, Ok, this is a tough one, and it might not even be possible, but no harm in asking I guess. I have a Buffalo Terastation file server that I use for network attached storage. After a couple of phone calls to customer services I realised that there is no way to backup to disk encrypted. In effect, I would be carrying unencrypted company data off-site daily, which is obviously unacceptable. I had a go at TrueCrypt, EncFS, and a few others, and as far as I could see all of them required that you install some software on the machine that is to use the file system, which makes sense. Unfortunately the firmware on the Terastation is closed and I cannot install any software (and I can't build from source either, since Buffalo didn't include a compiler). Are there any ways to copy files to disk, where as soon as they are written to the disk they are transparently encrypted, without having to install additional software? I'm not sure it matters too much, but the Terastation firmware is Linux based, although as I mentioned, closed. Many thanks, Andreas

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  • Nightmare: Upgrading Tomcat 5.5 to 6.0

    - by pavanlimo
    I'm trying to upgrade a perfectly running embedded Tomcat 5.5 to Tomcat 6.0. I understand that all I need to do is replace Tomcat 5.5 jars with 6.0. That's what I did. So I replaced the following jars: catalina-5.0.28.jar catalina-5.5.9.jar catalina-optional-5.5.9.jar commons-el.jar commons-modeler-1.1.0.jar jasper-compiler-jdt.jar jasper-compiler.jar jasper-runtime.jar jmx-5.0.28.jar jsp-api-2.0.jar naming-factory.jar naming-resources.jar servlet-api-2.4.jar servlets-default.jar tomcat-coyote.jar tomcat-http.jar tomcat-util.jar with: annotations-api.jar catalina.jar jasper.jar tomcat-dbcp.jar catalina-ant.jar el-api.jar jsp-api.jar tomcat-i18n-es.jar catalina-ha.jar jasper-el.jar servlet-api.jar tomcat-i18n-fr.jar catalina-tribes.jar jasper-jdt.jar tomcat-coyote.jar tomcat-i18n-ja.jar tomcat-juli.jar As soon as I start the server, I get the following message in the logs at INFO level: INFO: Starting Servlet Engine: Apache Tomcat/6.0.29 Dec 31, 2010 6:04:18 AM org.apache.catalina.loader.WebappClassLoader validateJarFile INFO: validateJarFile(/usr/local/blah/blue/./WEB-INF/lib/servlet-api.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class Based on the this explanation, I need to remove a jar file which has a conflicting Servlet.class. I swear to God, there is no other conflicting jar file, I grepped system wide for Servlet.class, it matched only servlet-api.jar. I also downloaded javaee.jar and replaced it by servlet-api.jar, to same avail. Having tried lot of these stuff, I did not have much to look upto, so set the tomcat logging level to ALL. In the log I could see that it is trying to check for Servlet.class in each and every jar it is loading until it finds servlet-api.jar and throws "jar not loaded" message as soon as it finds servlet-api.jar. See below: FINE: Checking for javax/servlet/Servlet.class Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappLoader setRepositories FINE: Deploy JAR /WEB-INF/lib/servlet-api.jar to /usr/local/blah/blue/./WEB-INF/lib/servlet-api.jar Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappClassLoader addJar FINE: addJar(/WEB-INF/lib/servlet-api.jar) Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappClassLoader validateJarFile FINE: Checking for javax/servlet/Servlet.class Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappClassLoader validateJarFile INFO: validateJarFile(/usr/local/blah/blue/./WEB-INF/lib/servlet-api.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class Jan 2, 2011 7:39:33 AM org.apache.catalina.loader.WebappLoader setRepositories Please note however, that Tomcat starts successfully! And as soon as I hit the URL on the browser, I get blank page(this may be in my case only, I guess 'cuz of my web.xml, sorta different from most. Other people on the internet have got Error 404 instead.) with following log statements(at finest level) Jan 2, 2011 9:40:01 AM org.apache.catalina.connector.CoyoteAdapter parseSessionCookiesId FINE: Requested cookie session id is 0FBA716E3F9B0147C3AF7ABAE3B1C27B Jan 2, 2011 9:40:01 AM org.apache.catalina.authenticator.AuthenticatorBase invoke FINE: Security checking request GET /login.jsp Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: Checking constraint 'SecurityConstraint[protected]' against GET /login.jsp --> false Jan 2, 2011 9:40:01 AM org.apache.catalina.realm.RealmBase findSecurityConstraints FINE: No applicable constraint located Jan 2, 2011 9:40:01 AM org.apache.catalina.authenticator.AuthenticatorBase invoke FINE: Not subject to any constraint Jan 2, 2011 9:40:01 AM org.apache.catalina.core.StandardWrapper allocate FINEST: Returning non-STM instance I'm not sure if the above log message is important, but I'm for all-out disclosure here. One interesting thing though, I manually created a dummy jsp file containing only "helloooo" just outside WEB-INF folder(no security constraints for this file). This file was accessible and could be displayed. But, all my jsp's and classes are inside WEB-INF(ofcourse). Sick and tired of this issue, please help me solve it. I've already spent 20-24 hours on this unsuccessfully. Any pointers directions hints leads?

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  • The speed of .NET in numerical computing

    - by Yin Zhu
    In my experience, .net is 2 to 3 times slower than native code. (I implemented L-BFGS for multivariate optimization). I have traced the ads on stackoverflow to http://www.centerspace.net/products/ the speed is really amazing, the speed is close to native code. How can they do that? They said that: Q. Is NMath "pure" .NET? A. The answer depends somewhat on your definition of "pure .NET". NMath is written in C#, plus a small Managed C++ layer. For better performance of basic linear algebra operations, however, NMath does rely on the native Intel Math Kernel Library (included with NMath). But there are no COM components, no DLLs--just .NET assemblies. Also, all memory allocated in the Managed C++ layer and used by native code is allocated from the managed heap. Can someone explain more to me? Thanks!

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  • Compiling ruby1.9.1 hangs and fills swap!

    - by nfm
    I'm compiling Ruby 1.9.1-p376 under Ubuntu 8.04 server LTS (64-bit), by doing the following: $ ./configure $ make $ sudo make install ./configure works without complaints. make hangs indefinitely until all my RAM and swap is gone. It get stuck after the following output: compiling ripper make[1]: Entering directory `/tmp/ruby1.9.1/ruby-1.9.1-p376/ext/ripper' gcc -I. -I../../.ext/include/x86_64-linux -I../.././include -I../.././ext/ripper -I../.. -I../../. -DRUBY_EXTCONF_H=\"extconf.h\" -fPIC -O2 -g -Wall -Wno-parentheses -o ripper.o -c ripper.c If I run the gcc command by hand, with the -v argument to get verbose output, it hangs after the following: Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.2.4 (Ubuntu 4.2.4-1ubuntu4) /usr/lib/gcc/x86_64-linux-gnu/4.2.4/cc1 -quiet -v -I. -I../../.ext/include/x86_64-linux -I../.././include -I../.././ext/ripper -I../.. -I../../. -DRUBY_EXTCONF_H="extconf.h" ripper.c -quiet -dumpbase ripper.c -mtune=generic -auxbase-strip ripper.o -g -O2 -Wall -Wno-parentheses -version -fPIC -fstack-protector -fstack-protector -o /tmp/ccRzHvYH.s ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.2.4/../../../../x86_64-linux-gnu/include" ignoring nonexistent directory "/usr/include/x86_64-linux-gnu" ignoring duplicate directory "../.././ext/ripper" ignoring duplicate directory "../../." #include "..." search starts here: #include <...> search starts here: . ../../.ext/include/x86_64-linux ../.././include ../.. /usr/local/include /usr/lib/gcc/x86_64-linux-gnu/4.2.4/include /usr/include End of search list. GNU C version 4.2.4 (Ubuntu 4.2.4-1ubuntu4) (x86_64-linux-gnu) compiled by GNU C version 4.2.4 (Ubuntu 4.2.4-1ubuntu4). GGC heuristics: --param ggc-min-expand=47 --param ggc-min-heapsize=32795 Compiler executable checksum: 6e11fa7ca85fc28646173a91f2be2ea3 I just compiled ruby on another computer for reference, and it took about 10 seconds to print the following output (after the above Compiler executable checksum line): COLLECT_GCC_OPTIONS='-v' '-I.' '-I../../.ext/include/i686-linux' '-I../.././include' '-I../.././ext/ripper' '-I../..' '-I../../.' '-DRUBY_EXTCONF_H="extconf.h"' '-D_FILE_OFFSET_BITS=64' '-fPIC' '-O2' '-g' '-Wall' '-Wno-parentheses' '-o' 'ripper.o' '-c' '-mtune=generic' '-march=i486' as -V -Qy -o ripper.o /tmp/cca4fa7R.s GNU assembler version 2.20 (i486-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.20 COMPILER_PATH=/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/ LIBRARY_PATH=/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/i486-linux-gnu/4.4.1/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-v' '-I.' '-I../../.ext/include/i686-linux' '-I../.././include' '-I../.././ext/ripper' '-I../..' '-I../../.' '-DRUBY_EXTCONF_H="extconf.h"' '-D_FILE_OFFSET_BITS=64' '-fPIC' '-O2' '-g' '-Wall' '-Wno-parentheses' '-o' 'ripper.o' '-c' '-mtune=generic' '-march=i486' I have absolutely no clue what could be going wrong here - any ideas where I should start?

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  • Cython Speed Boost vs. Usability

    - by zubin71
    I just came across Cython, while I was looking out for ways to optimize Python code. I read various posts on stackoverflow, the python wiki and read the article "General Rules for Optimization". Cython is something which grasps my interest the most; instead of writing C-code for yourself, you can choose to have other datatypes in your python code itself. Here is a silly test i tried, #!/usr/bin/python # test.pyx def test(value): for i in xrange(value): i**2 if(i==1000000): print i test(10000001) $ time python test.pyx real 0m16.774s user 0m16.745s sys 0m0.024s $ time cython test.pyx real 0m0.513s user 0m0.196s sys 0m0.052s Now, honestly, i`m dumbfounded. The code which I have used here is pure python code, and all I have changed is the interpreter. In this case, if cython is this good, then why do people still use the traditional Python interpretor? Are there any reliability issues for Cython?

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  • large amount of data in many text files - how to process?

    - by Stephen
    Hi, I have large amounts of data (a few terabytes) and accumulating... They are contained in many tab-delimited flat text files (each about 30MB). Most of the task involves reading the data and aggregating (summing/averaging + additional transformations) over observations/rows based on a series of predicate statements, and then saving the output as text, HDF5, or SQLite files, etc. I normally use R for such tasks but I fear this may be a bit large. Some candidate solutions are to 1) write the whole thing in C (or Fortran) 2) import the files (tables) into a relational database directly and then pull off chunks in R or Python (some of the transformations are not amenable for pure SQL solutions) 3) write the whole thing in Python Would (3) be a bad idea? I know you can wrap C routines in Python but in this case since there isn't anything computationally prohibitive (e.g., optimization routines that require many iterative calculations), I think I/O may be as much of a bottleneck as the computation itself. Do you have any recommendations on further considerations or suggestions? Thanks

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  • Video learning for database design

    - by donpal
    I'm trying to learn good relational database design (using mysql and php if that makes any difference). I've already done some database work, so I'm not totally clueless, but I suspect that my solutions may not have adhered to best practices for efficient searching, optimization, etc. Can someone suggest a good set of videos on the topic? If you know something is superb or has really made a difference in your own learning, please post your suggestion. Prefer videos, but books (as long as they're not too huge) are ok too. But prefer videos. Thank you

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  • Displaying thumbnails of images (present at different locations in the sdcard) in a listview

    - by frieza
    Hi all, I have several images present in different folders in my sdcard. I would like to display a list of thumbnails. So what I have done is while rendering any row in the list I read the file in an input stream, get the byte array, decode it to obtain a bitmap and set it in an imageview. So far so good. But when I scroll the list, the list scrolls in jerks. I believe this is because decoding a bitmap from byte array takes some time. What I would like to know is that, is there any optimization which I can do to improve the performance, or better still is there any better method to achieve what I want ?

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  • Installing VS2010 components with SP1 beta

    - by Jesus Rodriguez
    Hello, I hope this is the place for this kind of question. I have VS2010 ult with the Service Pack 1 beta installed. I want to play with F# and I need to install it. The problem is that because I have the SP1 installed, the VS DVD can't install the F# compiler. I click on add new feature, I click on F#, the installer says: "A selected drive is not longer valid. Please review your installation path settings before continuing with setup." Of course the path is correct and I can't change it anyway... I think that problem is because I have the SP1. I had the same problem in the past with VS2008 + SP1. What can I do? Uninstalling VS2010 is not an option, it take ages. Thank you.

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  • Efficiency of checking for null varbinary(max) column ?

    - by Moe Sisko
    Using SQL Server 2008. Example table : CREATE table dbo.blobtest (id int primary key not null, name nvarchar(200) not null, data varbinary(max) null) Example query : select id, name, cast((case when data is null then 0 else 1 end) as bit) as DataExists from dbo.blobtest Now, the query needs to return a "DataExists" column, that returns 0 if the blob is null, else 1. This all works fine, but I'm wondering how efficient it is. i.e. does SQL server need to read in the whole blob to its memory, or is there some optimization so that it just does enough reads to figure out if the blob is null or not ? (FWIW, the sp_tableoption "large value types out of row" option is set to OFF for this example).

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  • [OpenGL] I'm having an issue to use GLshort for representing Vertex, and Normal.

    - by Xylopia
    As my project gets close to optimization stage, I notice that reducing Vertex Metadata could vastly improve the performance of 3D rendering. Eventually, I've dearly searched around and have found following advices from stackoverflow. Using GL_SHORT instead of GL_FLOAT in an OpenGL ES vertex array How do you represent a normal or texture coordinate using GLshorts? Advice on speeding up OpenGL ES 1.1 on the iPhone Simple experiments show that switching from "FLOAT" to "SHORT" for vertex and normal isn't tough, but what troubles me is when you're to scale back verticies to their original size (with glScalef), normals are multiplied by the reciprocal of the scale. Then how do you use "short" for both vertex and normal at the same time? I've been trying this and that for about a full day, but I could only go for "float vertex w/ byte normal" or "short vertex w/ float normal" so far. Your help would be truly appreciated.

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  • Making Python scripts more user friendly?

    - by Michael Morisy
    I have a bunch of python scripts I've put together that cut down on busy work, but I'd like to be able to share them in an easier-to-use format for others to be used internally. The scripts aren't accessing anything local, just open API's across a couple web apps. Ideally: a) Users wouldn't have to have a python compiler installed b) They can be using Windows when running it. c) It's simple enough they can just click something, and it will work. I've tried some of the Windows Python executable compilers, but none have really worked well and I was considering just uploading it to a webserver and putting up some basic password access protection around it Any suggestions for sharing scripts?

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  • url with question mark considered as new http request?

    - by Navin Leon
    I am optimization my web page by implementing caching, so if I want the browser not to take data from cache, then I will append a dynamic number as query value. eg: google.com?val=823746 But some time, if I want to bring data from cache for the below url, the browser is making a new http request to server, its not taking data from cache. Is that because of the question mark in URL ? eg: http://google.com? Please provide some reference document link. Thanks in advance. Regards, Navin

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  • mysql partitioning

    - by Yang
    just want to verify that database partition is implemented only at the database level, when we query a partitioned table, we still do our normal query, nothing special with our queries, the optimization is performed automatically when parsing the query, is that correct? e.g. we have a table called 'address' with a column called 'country_code' and 'city'. so if i want to get all the addresses in New York, US, normally i wound do something like this: select * from address where country_code = 'US' and city = 'New York' if now the table is partitioned by 'country_code', and i know that now the query will only be executed on the partition which contains country_code = US. My question is do I need to explicitly specify the partition to query in my sql statement? or i still use the previous statement and the db server will optimize it automatically? Thanks in advance!

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  • Thread safe lockfree mutual ByteArray queue

    - by user313421
    A byte stream should be transferred and there is one producer thread and a consumer one. Speed of producer is higher than consumer most of the time, and I need enough buffered data for QoS of my application. I read about my problem and there are solutions like shared buffer, PipeStream .NET class ... This class is going to be instantiated many times on server so I need and optimized solution. Is it good idea to use a Queue of ByteArray ? If yes, I'll use an optimization algorithm to guess the Queue size and each ByteArray capacity and theoretically it fits my case. If no, I what's the best approach ? Please let me know if there's a good lock free thread safe implementation of ByteArray Queue in C# or VB. Thanks in advance

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  • removing duplicate strings from a massive array in java efficiently?

    - by Preator Darmatheon
    I'm considering the best possible way to remove duplicates from an (Unsorted) array of strings - the array contains millions or tens of millions of stringz..The array is already prepopulated so the optimization goal is only on removing dups and not preventing dups from initially populating!! I was thinking along the lines of doing a sort and then binary search to get a log(n) search instead of n (linear) search. This would give me nlogn + n searches which althout is better than an unsorted (n^2) search = but this still seems slow. (Was also considering along the lines of hashing but not sure about the throughput) Please help! Looking for an efficient solution that addresses both speed and memory since there are millions of strings involved without using Collections API!

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  • Visual Studio: Add necessary using directives with macro

    - by Kiril
    Hello guys, I am trying to do the following. Imagine you are reading some LINQ article and you decide to copy/paste some code from the article to a newly created project. In most cases, if you directly compile you will probably get an error for missing a using directives or assembly reference. I am trying to optimize the process where I have to go each keyword, click on it with the mouse and hit Shift + Alt + F10 to add the using directive. I know that it is not that much pain, but for the sake of optimization, is it possible and at what cost? Best Regards, Kiril

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  • Installing PHP with iconv on Mac OSX 10.6 gives error: "Undefined symbols for architecture x86_64"

    - by Jason
    I am setting up PHP on my local web server with iconv, which should be there by default, but I am getting the following error: Undefined symbols for architecture x86_64: "_iconv", referenced from: __php_iconv_strlen in iconv.o _php_iconv_string in iconv.o __php_iconv_strpos in iconv.o __php_iconv_appendl in iconv.o _zif_iconv_substr in iconv.o _zif_iconv_mime_encode in iconv.o _php_iconv_stream_filter_append_bucket in iconv.o ... (maybe you meant: _zif_iconv_strlen, _zif_iconv_strpos , _zif_iconv_mime_decode , _php_iconv_string , _zif_iconv_set_encoding , _zif_iconv_get_encoding , _zif_iconv_mime_decode_headers , _iconv_functions , _zif_iconv_mime_encode , _zif_iconv_strrpos , _iconv_module_entry , _iconv_globals , _zif_iconv_substr , _php_if_iconv , _zif_ob_iconv_handler ) ld: symbol(s) not found for architecture x86_64 Now, presumably this means that my iconv is not 64 bit. I tried to download libiconv and manually reinstall it with 64 bit, as such: CFLAGS='-arch i386 -arch ppc -arch ppc64 -arch x86_64' CCFLAGS='-arch i386 -arch ppc -arch ppc64 -arch x86_64' CXXFLAGS='-arch i386 -arch ppc -arch ppc64 -arch x86_64' ./configure But I get the following error: configure: error: in `/Users/jason/Downloads/libiconv-1.13.1': configure: error: C compiler cannot create executables See `config.log' for more details. In my config.lob file, it says at the bottom: configure: exit 77 Any suggestions?

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  • Weird behavior of std::vector

    - by Nima
    I have a class like this: class OBJ{...}; class A { public: vector<OBJ> v; A(int SZ){v.clear(); v.reserve(SZ);} }; A *a = new A(123); OBJ something; a->v.push_back(something); This is a simplified version of my code. The problem is in debug mode it works perfect. But in release mode it crashes at "push_back" line. (with all optimization flags OFF) I debugged it in release mode and the problem is in the constructor of A. the size of the vector is something really big with dummy values and when I clear it, it doesn't change... Do you know why? Thanks,

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  • Can a conforming C implementation #define NULL to be something wacky

    - by janks
    I'm asking because of the discussion that's been provoked in this thread: http://stackoverflow.com/questions/2597142/when-was-the-null-macro-not-0/2597232 Trying to have a serious back-and-forth discussion using comments under other people's replies is not easy or fun. So I'd like to hear what our C experts think without being restricted to 500 characters at a time. The C standard has precious few words to say about NULL and null pointer constants. There's only two relevant sections that I can find. First: 3.2.2.3 Pointers An integral constant expression with the value 0, or such an expression cast to type void * , is called a null pointer constant. If a null pointer constant is assigned to or compared for equality to a pointer, the constant is converted to a pointer of that type. Such a pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function. and second: 4.1.5 Common definitions <stddef.h> The macros are NULL which expands to an implementation-defined null pointer constant; The question is, can NULL expand to an implementation-defined null pointer constant that is different from the ones enumerated in 3.2.2.3? In particular, could it be defined as: #define NULL __builtin_magic_null_pointer Or even: #define NULL ((void*)-1) My reading of 3.2.2.3 is that it specifies that an integral constant expression of 0, and an integral constant expression of 0 cast to type void* must be among the forms of null pointer constant that the implementation recognizes, but that it isn't meant to be an exhaustive list. I believe that the implementation is free to recognize other source constructs as null pointer constants, so long as no other rules are broken. So for example, it is provable that #define NULL (-1) is not a legal definition, because in if (NULL) do_stuff(); do_stuff() must not be called, whereas with if (-1) do_stuff(); do_stuff() must be called; since they are equivalent, this cannot be a legal definition of NULL. But the standard says that integer-to-pointer conversions (and vice-versa) are implementation-defined, therefore it could define the conversion of -1 to a pointer as a conversion that produces a null pointer. In which case if ((void*)-1) would evaluate to false, and all would be well. So what do other people think? I'd ask for everybody to especially keep in mind the "as-if" rule described in 2.1.2.3 Program execution. It's huge and somewhat roundabout, so I won't paste it here, but it essentially says that an implementation merely has to produce the same observable side-effects as are required of the abstract machine described by the standard. It says that any optimizations, transformations, or whatever else the compiler wants to do to your program are perfectly legal so long as the observable side-effects of the program aren't changed by them. So if you are looking to prove that a particular definition of NULL cannot be legal, you'll need to come up with a program that can prove it. Either one like mine that blatantly breaks other clauses in the standard, or one that can legally detect whatever magic the compiler has to do to make the strange NULL definition work. Steve Jessop found an example of way for a program to detect that NULL isn't defined to be one of the two forms of null pointer constants in 3.2.2.3, which is to stringize the constant: #define stringize_helper(x) #x #define stringize(x) stringize_helper(x) Using this macro, one could puts(stringize(NULL)); and "detect" that NULL does not expand to one of the forms in 3.2.2.3. Is that enough to render other definitions illegal? I just don't know. Thanks!

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  • My code works in Debug mode, but not in Release mode.

    - by Nima
    Hi, I have a code in Visual Studio 2008 in C++ that works with files just by fopen and fclose. Everything works perfect in Debug mode. and I have tested with several datasets. But it doesn't work in release mode. It crashes all the time. I have turned off all the optimizations, also there is no dependency to anything(in the linker), and also I have set these: Optimization: Disabled(/Od) Keep Unreferenced Data. Do Not Remove Redundant Optimize for Windows98: NO I still keep wondering how it should not work under these circumstances. What else should I turn off to let it works as in debug mode? I think if it works in release mode but not in debug mode, it might be a coding fault but the other way looks weird. isn't it? I appreciate any help. --Nima

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  • Modifying a model and texture mid-game code

    - by MicroPirate
    Just have a question for anyone out there who knows some sort of game engine pretty well. What I am trying to implement is some sort of script or code that will allow me to make a custom game character and textures mid-game. A few examples would be along the lines of changing facial expressions and body part positions in the game SecondLife. I don't really need a particular language, feel free to use your favorite, I'm just really looking for an example on how to go about this. Also I was wondering if there is anyway to combine textures for optimization; for example if i wanted to add a tattoo to a character midgame, is there any code that could combine his body texture and the tattoo texture into one texture to use (this way I can simply just render one texture per body.) Any tips would be appreciated, sorry if the question is a wee bit to vauge.

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