Segmentation fault (core dumped) using stringstream in multithread application - c++

Question

I trying do simple threadsafe logger, which print messages to console.
// Test function for check logger. It is work
void test(double& diff)
{
std::vector<double> result;
for( int counter = 0; counter < 100000; ++counter)
{
result.push_back(clock());
std::string text = "counter = ";
text.append(std::to_string(counter));
LOG_MESSAGE(text); //<-- Correct log..
}
diff = clock() - result.front();
}
int main(int argc, char** argv)
{
double time2;
double time1;
std::vector<double> timerResult;
std::vector<std::thread> threadVector;
time1 = clock();
for(int i = 0; i < 5; ++i) //<-- Create 5 thread of test function
{
timerResult.push_back(0);
threadVector.push_back(std::thread(test, std::ref(timerResult[i])));
}
for(std::thread& t : threadVector)
t.join();
time2 = clock(); //<-- Threads is finished
double res = 0;
for(double tRes : timerResult)
res += tRes;
res = res / static_cast<double>(CLOCKS_PER_SEC);
std::string message; //<-- Generate final message
message.append("Timer: ")
.append(std::to_string((time2 - time1) / (double)CLOCKS_PER_SEC))
.append(" - thread timer: ")
.append(std::to_string(res));
LOG_MESSAGE(message); //<-- Crash inside!!
return 0;
}
Logger is good working in threads. But when I try log in main() function that call SIGSEGV signal in destructor of std::ostringstream (in function of construct log message):
static Logger::Core logger; //<--Global Logger variable
#define LOG_MESSAGE( TEXT ) logger.addNoteInLog(TEXT) //<-- Define for log message
void Core::addNoteInLog(const Message &message) //<-- threadsafe log function
{
std::string text;
message.generateString(text); //<-- [Crash here] generate log message
g_lock.lock();
std::cout << text;
g_lock.unlock();
}
void Message::generateString(std::string& text) const
{
text.clear();
tm *ltm = localtime(&mDate);
std::ostringstream data; //<-- [Crash here] function is finished, but cannot destruct object.
data << 1900 + ltm->tm_year << "/"
<< 1 + ltm->tm_mon << "/"
<< ltm->tm_mday << "\t";
data << "[INF] - ";
data << std::this_thread::get_id() << " - "
<< mMessage << "\n";
text = data.str();
}
I dont understand why logger in threads is work, but in main() function crashed. Using the exclusion method, I found out when the error is occurred:
when I use 5 (or more) threads
when test function is not empty
when in generateString use stringstream or ostringstream or string.append() (in last case application crash in std::string destructor in same place)
What say debugger in QtCreater.
Build in Ubuntu OS, gcc version 5.4.0, compilation flags: -std=c++17 -pthread -Wall
This is my git repository with error.

Answer 1

Problem solved.
As it was said in the comments, line threadVector.push_back(std::thread(test, std::ref(timerResult[i]))); is not correct, because memory reallocation in timerResult was done after calling push_back 5 times, and passing reference by ref(timerResult[i]) is incorrect.
Correct code:
int main(int argc, char** argv)
{
double time2;
double time1;
std::vector<double> timerResult (5); //<-- Create filling of vector
std::vector<std::thread> threadVector;
time1 = clock();
for(int i = 0; i < 5; ++i)
{
//timerResult.push_back(0); //<-- incorrect filling of vector
threadVector.push_back(std::thread(test, std::ref(timerResult[i])));
}
for(std::thread& t : threadVector)
t.join();
time2 = clock();
...
}