Pthread loop function never gets called - c++

Question

Below is my code, my problem is that readEvent() function never gets called.
Header file
class MyServer
{
public :
MyServer(MFCPacketWriter *writer_);
~MyServer();
void startReading();
void stopReading();
private :
MFCPacketWriter *writer;
pthread_t serverThread;
bool stopThread;
static void *readEvent(void *);
};
CPP file
MyServer::MyServer(MFCPacketWriter *writer_):writer(writer_)
{
serverThread = NULL;
stopThread = false;
LOGD(">>>>>>>>>>>>> constructed MyServer ");
}
MyServer::~MyServer()
{
writer = NULL;
stopThread = true;
}
void MyServer::startReading()
{
LOGD(">>>>>>>>>>>>> start reading");
if(pthread_create(&serverThread,NULL,&MyServer::readEvent, this) < 0)
{
LOGI(">>>>>>>>>>>>> Error while creating thread");
}
}
void *MyServer::readEvent(void *voidptr)
{
// this log never gets called
LOGD(">>>>>>>>>>>>> readEvent");
while(!MyServer->stopThread){
//loop logic
}
}
Another class
MyServer MyServer(packet_writer);
MyServer.startReading();

Answer 1

Since you are not calling pthread_join, your main thread is terminating without waiting for your worker thread to finish.
Here is a simplified example that reproduces the problem:
#include <iostream>
#include <pthread.h>
class Example {
public:
Example () : thread_() {
int rcode = pthread_create(&thread_, nullptr, Example::task, nullptr);
if (rcode != 0) {
std::cout << "pthread_create failed. Return code: " << rcode << std::endl;
}
}
static void * task (void *) {
std::cout << "Running task." << std::endl;
return nullptr;
}
private:
pthread_t thread_;
};
int main () {
Example example;
}
View Results
No output is produced when running this program, even though pthread_create was successfully called with Example::task as the function parameter.
This can be fixed by calling pthread_join on the thread:
#include <iostream>
#include <pthread.h>
class Example {
public:
Example () : thread_() {
int rcode = pthread_create(&thread_, nullptr, Example::task, nullptr);
if (rcode != 0) {
std::cout << "pthread_create failed. Return code: " << rcode << std::endl;
}
}
/* New code below this point. */
~Example () {
int rcode = pthread_join(thread_, nullptr);
if (rcode != 0) {
std::cout << "pthread_join failed. Return code: " << rcode << std::endl;
}
}
/* New code above this point. */
static void * task (void *) {
std::cout << "Running task." << std::endl;
return nullptr;
}
private:
pthread_t thread_;
};
int main () {
Example example;
}
View Results
Now the program produces the expected output:
Running task.
In your case, you could add a call to pthread_join to the destructor of your MyServer class.