Assertion failed on __pthread_mutex_cond_lock_full in a load test - c++

Question

I used the following code to create a timer object in my c++ application running on a debian 8.
class Timer
{
private:
std::condition_variable cond_;
std::mutex mutex_;
int duration;
void *params;
public:
Timer::Timer(void (*func)(void*))
{
this->handler = func;
this->duration = 0;
this->params = NULL;
};
Timer::~Timer(){};
void Timer::start(int duree, void* handlerParams)
{
this->duration = duree;
this->params = handlerParams;
/*
* Launch the timer thread and wait it
*/
std::thread([this]{
std::unique_lock<std::mutex> mlock(mutex_);
std::cv_status ret = cond_.wait_for(mlock,
std::chrono::seconds(duration));
if ( ret == std::cv_status::timeout )
{
handler(params);
}
}).detach();
};
void Timer::stop()
{
cond_.notify_all();
}
};
It works correctly under gdb and under normal conditions, but in a load test of 30 requests or more, it crashes with the assertion :
nptl/pthread_mutex_lock.c:350: __pthread_mutex_cond_lock_full: Assertion `(-(e)) != 3 || !robust' failed.
I don't understand the cause of this assertion. Can anyone help me please ??
Thank you

Answer 1

Basically you have a detached thread that accesses the timer object, so it's likely that you destroyed the Timer object but the thread is still running and accessing it's member(mutex, conditional variable).
The assert itself says, from glibc source code, that the owner of the mutex has died.

Answer 2

Thanks a lot for your comments ! I'll try to change the thread detach, and do the load tests.
This is a MVCE of my problem, which is a part of a huge application.
/**
* \file Timer.hxx
* \brief Definition of Timer class.
*/
#include <chrono>
#include <thread>
#include <mutex>
#include <condition_variable>
class Timer
{
private:
std::condition_variable cond_;
std::mutex mutex_;
int duration;
void *params;
public:
Timer(void (*func)(void*));
~Timer();
void (*handler)(void*);
void start(int duree, void* handlerParams);
void stop();
};
/*
* Timer.cxx
*/
#include "Timer.hxx"
Timer::Timer(void (*func)(void*))
{
//this->set_handler(func, params);
this->handler = func;
this->duration = 0;
this->params = NULL;
}
Timer::~Timer()
{
}
void Timer::start(int duree, void* handlerParams)
{
this->duration = duree;
this->params = handlerParams;
/*
* Launch the timer thread and wait it
*/
std::thread([this]{
std::unique_lock<std::mutex> mlock(mutex_);
std::cv_status ret = cond_.wait_for(mlock, std::chrono::seconds(duration));
if ( ret == std::cv_status::timeout )
{
handler(params);
}
}).detach();
}
void Timer::stop()
{
cond_.notify_all();
}
/*
* MAIN
*/
#include <stdio.h>
#include <iostream>
#include <unistd.h>
#include "Timer.hxx"
using namespace std;
void timeoutHandler(void* params)
{
char* data= (char*)params;
cout << "Timeout triggered !! Received data is: " ;
if (data!=NULL)
cout << data << endl;
}
int main(int argc, char **argv)
{
int delay=5;
char data[20] ="This is a test" ;
Timer *t= new Timer(&timeoutHandler) ;
t->start(delay, data);
cout << "Timer started !! " << endl;
sleep(1000);
t->stop();
delete t;
cout << "Timer deleted !! " << endl;
return 0;
}