I'm encountering persistent data race warnings in my C++ parallel program despite using mutexes. I've implemented a solution using OpenMP and mutexes to synchronize access to shared data, but I continue to receive ThreadSanitizer warnings regarding data races.
Code Overview:
I have a program that reads data from a file, performs parallel computations on it, and faces issues with the memory deallocation. The relevant portions of the code involve managing a shared vector using OpenMP parallelism and mutexes.
#include <fstream>
#include <sstream>
#include <iostream>
#include <vector>
#include <cstring>
#include <cmath>
#include <omp.h>
#include <mutex>
void readTextPointList(int n, int d, const std::string &strFileName, std::vector<std::vector<double>> &result)
{
std::vector<std::vector<double>> PointList;
std::string strLine;
std::ifstream inFile(strFileName);
if (inFile.is_open())
{
int i = 0;
while (getline(inFile, strLine) && i < n)
{
if (strLine.size() != 0)
{
std::stringstream sin(strLine);
std::vector<double> values(d);
for (int j = 0; j < d; j++)
{
double aa;
sin >> aa;
values[j] = aa;
}
PointList.push_back(values);
i++;
}
}
inFile.close();
// Use std::move to transfer ownership
result = std::move(PointList);
}
else
{
std::cout << "Error: Unable to open file." << std::endl;
}
}
std::mutex solveMutex;
void solve(std::vector<std::vector<double>> &data, size_t width, size_t start)
{
std::vector<double> tuple(width);
{
std::lock_guard<std::mutex> lock(solveMutex); // Lock the critical section
for (size_t i = 0; i < width; ++i)
{
tuple[i] = data[start][i];
}
}
// No need to unlock explicitly; std::lock_guard takes care of it when it goes out of scope
}
auto main(int argc, char **argv) -> int
{
if (argc < 2)
{
std::cout << "Usage: DIMENSIONALITY WINDOW" << std::endl;
return 0;
}
size_t width = strtoul(argv[1], nullptr, 10);
size_t datasize = strtoul(argv[2], nullptr, 10);
// Read the data into a shared vector
std::string filename = "mydata.txt";
std::vector<std::vector<double>> data;
readTextPointList(datasize, width, filename, data);
int core_number = 2;
int step = datasize / core_number + 1;
#pragma omp parallel for schedule(dynamic)
for (int i = core_number - 1; i >= 0; i--)
{
solve(data, width, i * step);
}
return 0;
}
Compilation:
I'm compiling the code with the following commands:
g++ -Wall -g -Wextra -fsanitize=thread -pedantic -std=c++20 -O3 -m64 -fopenmp main.cpp
Issue Details:
Despite using a mutex (solveMutex) to protect critical sections, I'm consistently receiving ThreadSanitizer warnings related to data races. The warnings specifically point to memory deallocation functions such as operator delete.
What I've Tried:
std::lock_guard<std::mutex>.Environment:
I would appreciate any insights into why these data race warnings persist and how to resolve them effectively. Additionally, any suggestions on improving the overall design or handling memory would be valuable.
==================
WARNING: ThreadSanitizer: data race (pid=25822)
Write of size 8 at 0x7b0800000060 by main thread:
#0 operator delete(void*, unsigned long) ../../../../src/libsanitizer/tsan/tsan_new_delete.cpp:150 (libtsan.so.0+0x8e878)
#1 __gnu_cxx::new_allocator<double>::deallocate(double*, unsigned long) /usr/include/c++/11/ext/new_allocator.h:145 (a.out+0x484c)
#2 std::allocator<double>::deallocate(double*, unsigned long) /usr/include/c++/11/bits/allocator.h:199 (a.out+0x484c)
#3 std::allocator_traits<std::allocator<double> >::deallocate(std::allocator<double>&, double*, unsigned long) /usr/include/c++/11/bits/alloc_traits.h:496 (a.out+0x484c)
#4 std::_Vector_base<double, std::allocator<double> >::_M_deallocate(double*, unsigned long) /usr/include/c++/11/bits/stl_vector.h:354 (a.out+0x484c)
#5 std::_Vector_base<double, std::allocator<double> >::~_Vector_base() /usr/include/c++/11/bits/stl_vector.h:335 (a.out+0x484c)
#6 std::vector<double, std::allocator<double> >::~vector() /usr/include/c++/11/bits/stl_vector.h:683 (a.out+0x484c)
#7 void std::destroy_at<std::vector<double, std::allocator<double> > >(std::vector<double, std::allocator<double> >*) /usr/include/c++/11/bits/stl_construct.h:88 (a.out+0x484c)
#8 void std::_Destroy<std::vector<double, std::allocator<double> > >(std::vector<double, std::allocator<double> >*) /usr/include/c++/11/bits/stl_construct.h:149 (a.out+0x484c)
#9 void std::_Destroy_aux<false>::__destroy<std::vector<double, std::allocator<double> >*>(std::vector<double, std::allocator<double> >*, std::vector<double, std::allocator<double> >*) /usr/include/c++/11/bits/stl_construct.h:163 (a.out+0x484c)
#10 void std::_Destroy<std::vector<double, std::allocator<double> >*>(std::vector<double, std::allocator<double> >*, std::vector<double, std::allocator<double> >*) /usr/include/c++/11/bits/stl_construct.h:196 (a.out+0x484c)
#11 void std::_Destroy<std::vector<double, std::allocator<double> >*, std::vector<double, std::allocator<double> > >(std::vector<double, std::allocator<double> >*, std::vector<double, std::allocator<double> >*, std::allocator<std::vector<double, std::allocator<double> > >&) /usr/include/c++/11/bits/alloc_traits.h:848 (a.out+0x484c)
#12 std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >::~vector() /usr/include/c++/11/bits/stl_vector.h:680 (a.out+0x484c)
#13 main /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:90 (a.out+0x2c79)
Previous read of size 8 at 0x7b0800000060 by thread T5 (mutexes: write M11):
#0 solve(std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >&, unsigned long, unsigned long) /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:56 (a.out+0x310b)
#1 main._omp_fn.0 /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:86 (a.out+0x329d)
#2 <null> <null> (libgomp.so.1+0x1dc0d)
Mutex M11 (0x55bd20bbf160) created at:
#0 pthread_mutex_lock ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:4240 (libtsan.so.0+0x53908)
#1 __gthread_mutex_lock /usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:749 (a.out+0x30cf)
#2 std::mutex::lock() /usr/include/c++/11/bits/std_mutex.h:100 (a.out+0x30cf)
#3 std::lock_guard<std::mutex>::lock_guard(std::mutex&) /usr/include/c++/11/bits/std_mutex.h:229 (a.out+0x30cf)
#4 solve(std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >&, unsigned long, unsigned long) /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:53 (a.out+0x30cf)
#5 main._omp_fn.0 /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:86 (a.out+0x329d)
#6 <null> <null> (libgomp.so.1+0x1dc0d)
Thread T5 (tid=25828, running) created by main thread at:
#0 pthread_create ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:969 (libtsan.so.0+0x605b8)
#1 <null> <null> (libgomp.so.1+0x1e25f)
#2 __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58 (libc.so.6+0x29d8f)
SUMMARY: ThreadSanitizer: data race ../../../../src/libsanitizer/tsan/tsan_new_delete.cpp:150 in operator delete(void*, unsigned long)
==================
==================
WARNING: ThreadSanitizer: data race (pid=25822)
Write of size 8 at 0x7b3000000000 by main thread:
#0 operator delete(void*, unsigned long) ../../../../src/libsanitizer/tsan/tsan_new_delete.cpp:150 (libtsan.so.0+0x8e878)
#1 __gnu_cxx::new_allocator<std::vector<double, std::allocator<double> > >::deallocate(std::vector<double, std::allocator<double> >*, unsigned long) /usr/include/c++/11/ext/new_allocator.h:145 (a.out+0x487a)
#2 std::allocator<std::vector<double, std::allocator<double> > >::deallocate(std::vector<double, std::allocator<double> >*, unsigned long) /usr/include/c++/11/bits/allocator.h:199 (a.out+0x487a)
#3 std::allocator_traits<std::allocator<std::vector<double, std::allocator<double> > > >::deallocate(std::allocator<std::vector<double, std::allocator<double> > >&, std::vector<double, std::allocator<double> >*, unsigned long) /usr/include/c++/11/bits/alloc_traits.h:496 (a.out+0x487a)
#4 std::_Vector_base<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >::_M_deallocate(std::vector<double, std::allocator<double> >*, unsigned long) /usr/include/c++/11/bits/stl_vector.h:354 (a.out+0x487a)
#5 std::_Vector_base<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >::~_Vector_base() /usr/include/c++/11/bits/stl_vector.h:335 (a.out+0x487a)
#6 std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >::~vector() /usr/include/c++/11/bits/stl_vector.h:683 (a.out+0x487a)
#7 main /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:90 (a.out+0x2c79)
Previous read of size 8 at 0x7b3000000000 by thread T5 (mutexes: write M11):
#0 std::vector<double, std::allocator<double> >::operator[](unsigned long) /usr/include/c++/11/bits/stl_vector.h:1046 (a.out+0x30f6)
#1 solve(std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >&, unsigned long, unsigned long) /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:56 (a.out+0x30f6)
#2 main._omp_fn.0 /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:86 (a.out+0x329d)
#3 <null> <null> (libgomp.so.1+0x1dc0d)
Mutex M11 (0x55bd20bbf160) created at:
#0 pthread_mutex_lock ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:4240 (libtsan.so.0+0x53908)
#1 __gthread_mutex_lock /usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:749 (a.out+0x30cf)
#2 std::mutex::lock() /usr/include/c++/11/bits/std_mutex.h:100 (a.out+0x30cf)
#3 std::lock_guard<std::mutex>::lock_guard(std::mutex&) /usr/include/c++/11/bits/std_mutex.h:229 (a.out+0x30cf)
#4 solve(std::vector<std::vector<double, std::allocator<double> >, std::allocator<std::vector<double, std::allocator<double> > > >&, unsigned long, unsigned long) /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:53 (a.out+0x30cf)
#5 main._omp_fn.0 /home/walid/Desktop/minimise/build sanitize/1_________decl.cpp:86 (a.out+0x329d)
#6 <null> <null> (libgomp.so.1+0x1dc0d)
Thread T5 (tid=25828, running) created by main thread at:
#0 pthread_create ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:969 (libtsan.so.0+0x605b8)
#1 <null> <null> (libgomp.so.1+0x1e25f)
#2 __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58 (libc.so.6+0x29d8f)
SUMMARY: ThreadSanitizer: data race ../../../../src/libsanitizer/tsan/tsan_new_delete.cpp:150 in operator delete(void*, unsigned long)
==================
ThreadSanitizer: reported 2 warnings
I have also encountered this problem recently. After my search , I found that need to build the OpenMP runtime library with TSAN Can I use Thread Sanitizer for OpenMP programs? and Is clang's thread sanitizer reporting a false positive?. Hope this can solve your problem. Have a good day:D