C/C++ :: Getting Error While Using OpenMP Along With Map
Dec 19, 2012
I am using map for assigning an identifiers for a line from file in c++. Also i am using IDs for a pattern in line {name, operator, val} which is separated by ';'. I am using read_pub() for calculating how many patterns are there in a line.
I wrote code that finds the number of prime numbers in a range entered by the user. Now I'm attempting to make it run in parallel with the number of threads I assign it to have. I'm using blocking technique, so I'm assigning, in this scenario, 4 threads - 1/4 of the numbers in the range to the first array, and the next 1/4 of the numbers in the range to the next array and so on. Then I want to execute the prime number counting code in parallel. I'm using openMP to do this. I'm having difficulty setting it all up properly. I have a little experience with pthreads but little with openMP and am struggling in how this should be done.
I'm quite new to openMP, mostly used pthreads and mpi before. Now I like to tinker a bit with openMP, but haven't found any good docs, reference list or similar.
What's the equivalent to pthread's mutex lock in openMP?
Code: #pragma omp parallel for for(i=0; i<n ; i++){ // Do something intelligent... // If needed handle a shared variable. }
I'm trying to write a small brute force application in C on Ubuntu 14.04.1 using Code::Blocks with gcc-4.8.2. It's nothing special and just for practice.The focus is on a parallel procedure that generates strings by use of OpenMP. Every time a string is generated, the counter variable should be incremented. At the end, regardless of whether the search string was matched or not, it outputs the correct number of all generated strings (counts).It works fine so far.Here is my source code example:
Code:
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <omp.h> /* Global variables */ const char Literals[] = "abcdefghijklmnopqrstuvwxyz"; const int NLiterals = sizeof( Literals ) - 1; // NLiterals = 26 Bytes. const char SearchString[] = "test"; // I.e. until 'test' there are 355414 counts. char MatchString[16]; }
[code]...
This should speed up the process of generating strings. But if I do so, always when the program has a match the number of counted strings is wrong. Here are some possible "wrong" outputs: Code: Match: 'test'! 40710 tries. <-- number of tries (counts) is wrong! or Code: Match: 'test'! 40375 tries. <-- number of tries (counts) is wrong! But if the program doesn't have a match (i.e. when I change SearchString to something like the following line), then the number of counts is correct: Code: const char SearchString[] = "test0"; The only thing I have to do before, is to change the follow line from:
Code:
printf( " No match! %u tries. ", Count / 8 ); to Code: printf( " No match! %u tries. ", Count );
But also it can happen that there is no output. Like an infinite or endless loop. How can I improve the source code in order that the correct number of counts is always displayed and what can be the reason for the endless loops time after time? Both issues appears only by the use of Code: #pragma omp for schedule( dynamic ).
I'm trying to implement Parallel loop with OpenMP. I just googled and got the below sample, but it seems its not executing parallely. It takes same amount time for code which is with parallel and without parallel.
Without Parallel : It takes 39 secs. ----------------- for (int I=0;I<100000;I++){ cout<<I<<" "; }
With Parallel : It takes 39 secs. --------------
#include<omp.h> #pragma omp parallel { #pragma omp for for (int I=0;I<100000;I++) { cout<<I<<endl; } }
Why parallel is not working and it takes same time. My machine is Dual Core.
However, since it is multithreaded, I would like (and need!) to have one dedicated vector per thread. I haven't been able to find an example of how to do this online. Is it even possible?
I'm trying to optimize this code using openMP. The line I added made it run about twice as fast but I'm trying to figure out how to make it even faster. Could reshaping the loops potentially increase the speed?
//4 threads int listsize=15000; #pragma omp parallel for shared(f) private(i,j,hash) for(i = 0; i < listsize; i++) { printf("Thread: %d i: %zu wl_size: %zu ",omp_get_thread_num(),i,wl_size); for (j = 0; j < num; j++) { h = f[j] (getw(list, i)); c[h] = 1; } }
I am trying to parallelize some of my code with OpenMP. When I switch to using multiple threads I start getting random numbers that are out of the expected range.
Here is a small example:
Code: #include <stdio.h> #include </usr/local/include/gsl/gsl_rng.h> #include </usr/local/include/gsl/gsl_randist.h> int main() { int mySeed=0; const gsl_rng_type *T; T = gsl_rng_ranlxs2; gsl_rng *r_1 ;
[Code] .....
gsl_rng_uniform should only output number in the range [0,1) but with multiple threads it outputs larger number as well.
Cannot manage to find the error source when i try running the program, the first part of the program runs just fine its when i try to get the temperature one that i get the error
#include <iostream> #define pi 3.141592 using namespace std; int main() { double r, h; //declare variables for radious and height double Surfacearea;
I've just recently started to learn C++, and I'm encountering some errors I can't seem to figure out.
InventoryItem.h:
Code: #pragma once class InventoryItem { public: InventoryItem(string name, int amount); ~InventoryItem(void); string getName(void); int getAmount(void);
I am trying to make a program like a virtual machine, and therefore I need to have a virtual hard drive. I have it split across four files, each being exactly 67,108,864 bytes (at this point, the files consist of 0x00 throughout the entire file). When I try to write to the beginning of one of the files, I get a "EXC_BAD_ACCESS (code=1, address=0xff)" from Xcode.
I have no error compiling, but running my project it stops before entering a function and debugging I have an error about Segmentation fault. The function:
i was suppose to write a program that gives a divide error but output is not showing anything like it.I am using orwell devc++ 5.4.2 and all the default built tools(gcc compiler etc.) with default settings.so, what should i do to see this error?
Code:
#include<stdio.h> #include<conio.h> int main() { int a,b,c; float x; }
I've a code and it works on my linux laptop; however it doesnt work on a matrix server. Im getting error Code: file.c: In function CondCheck:file.c:40:3: warning: this decimal constant is unsigned only in ISO C90 [enabled by default] The code of the programme
Code:
#include <stdio.h> #include <string.h> #include <math.h> /*DECIMAL TO BINARY CONVERTER*/ int BinaryConverter (int bina) }
While trying to redo everything in c i have an error on a do while loop and i don't understand i've corrected everything else but i don't understand why the error occurs even though it says how to fix it it says error expected ) before token -line 18 part of code
Code:
int main(){ Beep (523,1000); // sound at 523 hertz for 1 000 milliseconds char cPresent; do }
[code]....
this is just extra bits i've added on to the assignment but I've worked on the c++ code for a week now i have less than a day to redo it
Here is my first program, I had to use a lot of if/ else statements. For some reason the last "else" (bolded) is giving me an error and not letting me run the program.
And yes, the if else's are indented properly, because there are no errors for the first 3 unit types, only for the last one ( 'F' ), and i have them all exactly in the same format.
I am writing a c++ program which uses a vector which contains rows and columns of a table.Unfortunately I got the following error:
IntelliSense: no instance of overloaded function "std::vector<_Ty, _Alloc>::push_back [with _Ty=CCellDescr *, _Alloc=std::allocator<CCellDescr *>]" matches the argument list
argument types are: (const CCellDescr) object type is: std::vector<CCellDescr *, std::allocator<CCellDescr *>>Here`s the code:
#include<iostream> #include<fstream> #include<vector> #include<string> #include<iterator> using namespace std;
I am working on my final project for my class and after finally getting it to compile with no errors to finding examples/tutorials and following skeleton code I cam encountering a problem.
The program runs, asks all the correct questions but when it displays the base pay and total pay for all 3 employees it comes back as ( -1.0743 blah blah )
When they work over 40 hours it works correctly but when they work under 40 hours it displays those weird numbers in those sections.
// Kevin Johnson -- Overtime Pay -- Final Assignment // Created 11/14/2013 // Edited 11/17/2013 #include "stdafx.h"
