Thread Synchronization Problem

[sijithjames]

Here i want to execute a thread through two different function.
Here i am getting synchronization problem. I want both task to execute concurrently.

functionA calling thread1 (Incrementing X value)
functionB calling thread1 (Decrementing X value)


How can i do it.. Plz give some suggestions and help.

[high_flyer]

What do you mean by "functionA calling thread1"
Do you mean you want to start thead1 in the main thread when functionA is called?

What exactly is the problem you are having?
Can you show relevant code?

Don't expect to be taught thread programming on a forum, but if you have a specific question, then please provide all information needed to help you.

[sijithjames]

Here i created a thread and created two instance of that thread. i want both object to call the run function cuncurrently

threadNew = new ServerThread(this);
threadNew1 = new ServerThread(this);

class ServerThread : public QThread
{
Q_OBJECT

public:
ServerThread(QObject *parent);
~ServerThread();

protected:
void run();

};

Here threadNew and threadNew1 are calling the run function but not in synchronized manner

How can i do this

[lonepsycho]

you dont need to call run concurenlty. just call it. and two threads starts to do their work.

[sijithjames]

I have two object of same thread

1. First threadNew have to call the run function
2. Then threadNew1 have to call the run function

Both have to call the run function alternatively, is it possible

Now what happening is both object is calling hte run function but calling order we cant predict.. Each time its calling in different order

i want treadNew-- treadNew1-- treadNew-- treadNew1 in this order

[high_flyer]

its hard to understand from your post what it is you want.
Please show the code that depicts your problem.

The code you posted shows no problem.
By the way,run() should be protected, you call start() to start the thread.

[lonepsycho]

since threading is being managed by OS, I doubt that you can predict which starts first. unless you make your main thread pause between calls, or ensure that the first thread is started before starting next thread.

[sijithjames]

secondCheck.cpp

#include "secondcheck.h"
#include <qobject.h>
#include <QMutex>
extern QMutex mutex;
secondCheck::secondCheck(QObject *parent)
: QThread(parent)
{
threadNew1 = new ServerThread(this);
exeThread();
}

void secondCheck:: exeThread()
{
mutex.lock();
printf(" secondCheck Started++++++++++++++++++++++\n");
threadNew1->start();
printf(" Second Task Ended++++++++++++++++++++++\n");
mutex.unlock();
}

secondCheck::~secondCheck()
{

}
secondcheck.h
#ifndef SECONDCHECK_H
#define SECONDCHECK_H

#include <QObject>
#include "serverthread.h"
#include <QtGui/QMainWindow>

#include <QThread>
#include <QMutex>

class secondCheck : public QThread
{
Q_OBJECT

public:
ServerThread *threadNew1;
secondCheck(QObject *parent);
~secondCheck();
void exeThread();
QMutex mutex;

private:

};

#endif // SECONDCHECK_H
serverthread.cpp

#include "serverthread.h"

QMutex mutex;

ServerThread::ServerThread(QObject *parent)
: QThread(parent)
{

}

void ServerThread::run()
{
printf("Inside Thread @@@@@@@@@@@@@@@@@@@\n");
}

ServerThread::~ServerThread()
{

}
serverthread.h
#ifndef SERVERTHREAD_H
#define SERVERTHREAD_H

#include <QThread>
#include <QMutex>

class ServerThread : public QThread
{
Q_OBJECT

public:
ServerThread(QObject *parent);
~ServerThread();

protected:
void run();

};
mutex_sample.cpp

#include "mutex_sample.h"
#include <QMutexLocker>
#include <QThread>
#include <QMutex>

extern QMutex mutex;


#define ITER 10
int global = 0;

mutex_sample::mutex_sample(QWidget *parent, Qt::WFlags flags)
: QMainWindow(parent, flags)
{
ui.setupUi(this);
threadNew = new ServerThread(this);
taskCheck= new secondCheck(this);
taskCheck->exeThread();
taskOne();
}


void mutex_sample:: mainTask(void)
{

threadNew->start();

}

void mutex_sample::taskOne(void)
{
mutex.lock();
printf("First Task Started......................\n");
mainTask();
printf("First Task Ended......................\n");
mutex.unlock();
}


mutex_sample::~mutex_sample()
{

}
mutex_sample.h
#ifndef MUTEX_SAMPLE_H
#define MUTEX_SAMPLE_H

#include <QtGui/QMainWindow>
#include "ui_mutex_sample.h"
#include <QMutexLocker>
#include <QThread>
#include "serverthread.h"
#include "secondcheck.h"


class mutex_sample : public QMainWindow
{
Q_OBJECT

public:

mutex_sample(QWidget *parent = 0, Qt::WFlags flags = 0);
~mutex_sample();
ServerThread *threadNew;
secondCheck *taskCheck;
//threadn thdn;
void mainTask(void);
void taskOne(void);
void taskTwo(void);

private:
Ui::mutex_sampleClass ui;
mutable QMutex mutex;
};


#endif // MUTEX_SAMPLE_H

Output
Here i am getting the printf inside run in irragular form

Expected ans
secondCheck Started++++++++++++++++++++++
Inside Thread @@@@@@@@@@@@@@@@@@@
Second Task Ended++++++++++++++++++++++
First Task Started......................
Inside Thread @@@@@@@@@@@@@@@@@@@
First Task Ended......................
secondCheck Started++++++++++++++++++++++
Inside Thread @@@@@@@@@@@@@@@@@@@
Second Task Ended++++++++++++++++++++++
First Task Started......................
Inside Thread @@@@@@@@@@@@@@@@@@@
First Task Ended......................
secondCheck Started++++++++++++++++++++++
Inside Thread @@@@@@@@@@@@@@@@@@@
Second Task Ended++++++++++++++++++++++
First Task Started......................
Inside Thread @@@@@@@@@@@@@@@@@@@
First Task Ended......................

please help

[lonepsycho]

since you expecting sequential execution of your "threads", not side by side, maybe it is more resonable just call two functions one after another?

[sijithjames]

will Mutex or semaphore can do this job

[lonepsycho]

mutex or semaphore can lock data being modified by thread, so the answer is - it depends on what you want to do.

[sijithjames]

i tried with mutex but not working...
Unfortunately not getting any feasible solution...

Thanks 4 helping me