Multiple timers in single Application

[wysota]

Dear then suggest me one example with 6 timers with different slots with different timers and they should run at a time.

It's not a problem to have six timers and execute them in time. It's a problem when you are trying to do more than your machine can handle.

Here is a simple example that shows that you can have six timers in an app:

#include <QtCore>
 
class Dummy : public QObject {
  Q_OBJECT
public:
  Dummy(){}
public slots:
  void timeout() {
    QTimer *timer = qobject_cast<QTimer*>(sender());
    if(!timer) return;
    qDebug() << "Now is" << QDateTime::currentDateTime() << "timer id:" << timer->property("timerId").toInt() << ", interval is" << timer->interval() << "ms";
  }
};
 
#include "main.moc"
 
int main(int argc, char **argv) {
  QCoreApplication app(argc, argv);
  Dummy d;
  for(int i=0;i<6;++i) {
    QTimer *timer = new QTimer(&app);
    timer->setInterval(50+(qrand() % 200));
    timer->setProperty("timerId", i);
    QObject::connect(timer, SIGNAL(timeout()), &d, SLOT(timeout()));
    timer->start();
  }
  return app.exec();
}

#include <QtCore>

class Dummy : public QObject {
  Q_OBJECT
public:
  Dummy(){}
public slots:
  void timeout() {
    QTimer *timer = qobject_cast<QTimer*>(sender());
    if(!timer) return;
    qDebug() << "Now is" << QDateTime::currentDateTime() << "timer id:" << timer->property("timerId").toInt() << ", interval is" << timer->interval() << "ms";
  }
};

#include "main.moc"

int main(int argc, char **argv) {
  QCoreApplication app(argc, argv);
  Dummy d;
  for(int i=0;i<6;++i) {
    QTimer *timer = new QTimer(&app);
    timer->setInterval(50+(qrand() % 200));
    timer->setProperty("timerId", i);
    QObject::connect(timer, SIGNAL(timeout()), &d, SLOT(timeout()));
    timer->start();
  }
  return app.exec();
}

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The main concept of my app is through tcp/ip client - server App. in which my app is client & which always sends 1 telegram every 100ms using "update_HmiScrLvl4".

and the telegram construction & values will produced by the other timers, so dat the constructed telegram can be sent to server using "update_HmiScrLvl4".

You don't need any threads for that nor any (not a single one!) timers. You just need to use QTcpSocket properly.

[pradeepreddyg95]

i am sending the simulator which u can test ur requirment plz test it.

---

Added after 10 minutes:

After executing first timer timeout slot then only it will move to second timer timeout slot.
Eg:
if first timer timeout slot takes 1sec to finish process. After finishing this 1 sec the second slot will excute.

---

Added after 51 minutes:

using visual studio 2005 for debugging

[d_stranz]

As Wysota said, if you are trying to do something in a slot that takes 1 s to finish, and you expect that slot to be executed every 100 ms, then it is more than your machine can handle, and no amount of threading or anything else is going to help that situation.

And, in your slot if you are not allowing any other events from the Qt event loop to be handled (for example, you don't call processEvents()), then the timeout signals from other timers will not be handled until after the first slot finishes. Furthermore, if the timer whose slot you are executing fires again while you are still in the slot code, that timeout will be ignored.

So, what your code is actually doing is allowing each timer to fire once every second, and the whole cycle repeats once every n seconds (n = # of timers).

[mahi6a1985]

i am sending the simulator which u can test ur requirment plz test it.

---

Added after 10 minutes:

After executing first timer timeout slot then only it will move to second timer timeout slot.
Eg:
if first timer timeout slot takes 1sec to finish process. After finishing this 1 sec the second slot will excute.

---

Added after 51 minutes:

using visual studio 2005 for debugging

Wat u hav explained n the code sample is good n working fine. Thanks a lot.

But wat i am asking is instead of running one after another means in ur example - After finishing this 1 sec the second slot will execute.

Instead of this, cant we run all timers together. means execute all the slots at a time wit diff intervals. Its a doubt of mine which being in my mind from many days, can't we ?.

[pradeepreddyg95]

what i have given code you can set different timer intervals it will work all together at a time no problem in that ... because each timer timeout slot will excute in a different thread that means if you start 2 timers with 100 ms interval two slots will execute same time in two different threads .

[mahi6a1985]

what i have given code you can set different timer intervals it will work all together at a time no problem in that ... because each timer timeout slot will excute in a different thread that means if you start 2 timers with 100 ms interval two slots will execute same time in two different threads .

Hi Pradeep,

After Applying your code to my huge amount of project. finally i got this error which is stopping my app y i don't know ?

ghgfh.jpg

[wysota]

"I told you but you wouldn't listen"

Functions ran in threads cannot access the GUI (i.e. MainWindow).

[mahi6a1985]

"I told you but you wouldn't listen"

Hi Wysota,

But wat am i suppose to do now ?

I hav tried all the ways. As said by u i hav even divided my Huge SLOTs processing into small small process and tried tooo.

but all in vain nothing helping....?

at least now my urgent requirement is that my application should run "update_HMIScrLvl4" timer and execute its slot at every 100ms, Whether the other 5 timers running or not this particular "update_HMIScrLvl4" should be execute its slot every 100MS. on High Priority this particular timer should run...?

[wysota]

But wat am i suppose to do now ?

Read the thread from the beginning and not get fixated on one possible solution.

I hav tried all the ways.

No, you haven't. You have been ignoring what we were saying so we stopped saying anything.

I'm pretty sure you can do with one timer and no extra threads at all.

[mahi6a1985]

It's not a problem to have six timers and execute them in time. It's a problem when you are trying to do more than your machine can handle.

Here is a simple example that shows that you can have six timers in an app:

#include <QtCore>
 
class Dummy : public QObject {
  Q_OBJECT
public:
  Dummy(){}
public slots:
  void timeout() {
    QTimer *timer = qobject_cast<QTimer*>(sender());
    if(!timer) return;
    qDebug() << "Now is" << QDateTime::currentDateTime() << "timer id:" << timer->property("timerId").toInt() << ", interval is" << timer->interval() << "ms";
  }
};
 
#include "main.moc"
 
int main(int argc, char **argv) {
  QCoreApplication app(argc, argv);
  Dummy d;
  for(int i=0;i<6;++i) {
    QTimer *timer = new QTimer(&app);
    timer->setInterval(50+(qrand() % 200));
    timer->setProperty("timerId", i);
    QObject::connect(timer, SIGNAL(timeout()), &d, SLOT(timeout()));
    timer->start();
  }
  return app.exec();
}

#include <QtCore>

class Dummy : public QObject {
  Q_OBJECT
public:
  Dummy(){}
public slots:
  void timeout() {
    QTimer *timer = qobject_cast<QTimer*>(sender());
    if(!timer) return;
    qDebug() << "Now is" << QDateTime::currentDateTime() << "timer id:" << timer->property("timerId").toInt() << ", interval is" << timer->interval() << "ms";
  }
};

#include "main.moc"

int main(int argc, char **argv) {
  QCoreApplication app(argc, argv);
  Dummy d;
  for(int i=0;i<6;++i) {
    QTimer *timer = new QTimer(&app);
    timer->setInterval(50+(qrand() % 200));
    timer->setProperty("timerId", i);
    QObject::connect(timer, SIGNAL(timeout()), &d, SLOT(timeout()));
    timer->start();
  }
  return app.exec();
}

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You don't need any threads for that nor any (not a single one!) timers. You just need to use QTcpSocket properly.

I hav tried this even this haven't solved my problem.

---

Added after 4 minutes:

Read the thread from the beginning and not get fixated on one possible solution.


No, you haven't. You have been ignoring what we were saying so we stopped saying anything.

I'm pretty sure you can do with one timer and no extra threads at all.

Dear Then tell me plz wat to do, i am running out of time... so dats d one reason n another thing i am beginner not even tried any sample "hello world" program also. I am a .net developer previously , now i am shifting to QT now. So am unable to understand wat u ppl say.

Only thing i can say is Sorry if i make u ppl think i ignored wat u said n help me Now...

[wysota]

I hav tried this even this haven't solved my problem.

"this" meaning what exactly? At the beginning of what you quoted I write that your problem is not related to having more than one timer and then I give you an example that you can run multiple timers without problem. If it doesn't work then it confirms what I said -- that this was not your problem.

Dear Then tell me plz wat to do, i am running out of time... so dats d one reason n another thing i am beginner not even tried any sample "hello world" program also. I am a .net developer previously , now i am shifting to QT now. So am unable to understand wat u ppl say.

First of all start using proper language instead of that trash sms speech. Then rethink your approach --- think what you really need and not what you think you need. The fact that you come from .net environment is meaningless as you wouldn't be able to do it this way in .net too. Your problem is trying to do more than your machine can handle. So instead of trying to find a way to spawn more timers (which leads to nothing), think how to obtain the same result doing less.

[pradeepreddyg95]

hi mahi can you post your code how you implemented

[mahi6a1985]

hi mahi can you post your code how you implemented

Hi Pradeep,

same i have incorporated your function names and same as it is how u have been implemented i have done that. Same as the Simulator app which u have given. You can find the Screenshot what the error i got.

"this" meaning what exactly? At the beginning of what you quoted I write that your problem is not related to having more than one timer and then I give you an example that you can run multiple timers without problem. If it doesn't work then it confirms what I said -- that this was not your problem.



First of all start using proper language instead of that trash sms speech. Then rethink your approach --- think what you really need and not what you think you need. The fact that you come from .net environment is meaningless as you wouldn't be able to do it this way in .net too. Your problem is trying to do more than your machine can handle. So instead of trying to find a way to spawn more timers (which leads to nothing), think how to obtain the same result doing less.

Dear Sir ,

I know that is what the problem is. For that what i have to do i am asking. if, is their any solution then help me Else Thanks for sharing the knowledge still now.

[wysota]

I know that is what the problem is. For that what i have to do i am asking. if, is their any solution then help me Else Thanks for sharing the knowledge still now.

I can't suggest anything without knowing what each of the routines you are running is supposed to do. I already suggested some things earlier in this thread -- reduce frequency of your updates. If you post the actual code you have in the routines maybe I can suggest more.

[pradeepreddyg95]

if you are displaying the screen shot i cant estimate how you implement if you post your code i can help ...

[mahi6a1985]

I can't suggest anything without knowing what each of the routines you are running is supposed to do. I already suggested some things earlier in this thread -- reduce frequency of your updates. If you post the actual code you have in the routines maybe I can suggest more.

Ok Thanks and sorry cant post my code. Can i know how to calculate, how much time is taken to execute a slot. As i am having so much of processing in each slots, may be my timeout intervals are not working i think. So i want to know how much time it takes for each slot to start and end ?

[wysota]

Can i know how to calculate, how much time is taken to execute a slot.

If you want a precise value, you have to use some profiler (such as callgrind on Linux). If you just need an estimate, create a QTime object at the beginning of the slot, start it and at the end of the slot print the value returned by QTime::elapsed() to the console.

[mahi6a1985]

If you want a precise value, you have to use some profiler (such as callgrind on Linux). If you just need an estimate, create a QTime object at the beginning of the slot, start it and at the end of the slot print the value returned by QTime::elapsed() to the console.

Hi Wysota,
using your code i came to know that all of my slots connected to timers are executed(i.e. Each Slot start to End of it.) below 10MS. Thanks for this.
But now what i want is that each slots should be executed every 500ms. means the slots should be called every 500ms some of them and some them every 250ms. Can you suggest me anything please.

So this means ---

1st timer SLOT to be called every 500ms and for execution of slot it takes 6ms.
2nd timer SLOT to be called every 600ms and for execution of slot it takes 4ms.
3rd timer SLOT to be called every 100ms and for the execution of slot it takes 4ms.
4th timer SLOT to be called every 1000ms and for the execution of slot it takes 6ms.
5th timer SLOT to be called every 3000ms and for the execution of slot it takes 3ms.
6th timer SLOT to be called every 5000ms and for the execution of slot it takes 2ms.

Note :- The execution of slot time i given above is calculated using the QTime::elapsed() for each of my slots.

Thanks in Advance.

[ChrisW67]

You already have everything you need in this thread. Here it is laid out in verbose code. One thread, six timers, six processes (slots):

#include <QtCore>
#include <QDebug>
 
class Dummy: public QObject
{
    Q_OBJECT
public:
    Dummy(QObject *p = 0): QObject(p)
    {
        connect(&t1, SIGNAL(timeout()), SLOT(p1()));
        connect(&t2, SIGNAL(timeout()), SLOT(p2()));
        connect(&t3, SIGNAL(timeout()), SLOT(p3()));
        connect(&t4, SIGNAL(timeout()), SLOT(p4()));
        connect(&t5, SIGNAL(timeout()), SLOT(p5()));
        connect(&t6, SIGNAL(timeout()), SLOT(p6()));
 
        time.start();
        t1.start(500);
        t2.start(600);
        t3.start(100);
        t4.start(1000);
        t5.start(3000);
        t6.start(5000);
    }
 
public slots:
    void p1() {  qDebug() << "p1 at" << time.elapsed(); usleep(6000); }
    void p2() {  qDebug() << "p2 at" << time.elapsed(); usleep(4000); }
    void p3() {  qDebug() << "p3 at" << time.elapsed(); usleep(4000); }
    void p4() {  qDebug() << "p4 at" << time.elapsed(); usleep(6000); }
    void p5() {  qDebug() << "p5 at" << time.elapsed(); usleep(3000); }
    void p6() {  qDebug() << "p6 at" << time.elapsed(); usleep(2000); }
 
private:
    QTime time;
    QTimer t1, t2, t3, t4, t5, t6;
};
 
int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
    Dummy d;
    return app.exec();
}
#include "main.moc"

#include <QtCore>
#include <QDebug>

class Dummy: public QObject
{
    Q_OBJECT
public:
    Dummy(QObject *p = 0): QObject(p)
    {
        connect(&t1, SIGNAL(timeout()), SLOT(p1()));
        connect(&t2, SIGNAL(timeout()), SLOT(p2()));
        connect(&t3, SIGNAL(timeout()), SLOT(p3()));
        connect(&t4, SIGNAL(timeout()), SLOT(p4()));
        connect(&t5, SIGNAL(timeout()), SLOT(p5()));
        connect(&t6, SIGNAL(timeout()), SLOT(p6()));

        time.start();
        t1.start(500);
        t2.start(600);
        t3.start(100);
        t4.start(1000);
        t5.start(3000);
        t6.start(5000);
    }

public slots:
    void p1() {  qDebug() << "p1 at" << time.elapsed(); usleep(6000); }
    void p2() {  qDebug() << "p2 at" << time.elapsed(); usleep(4000); }
    void p3() {  qDebug() << "p3 at" << time.elapsed(); usleep(4000); }
    void p4() {  qDebug() << "p4 at" << time.elapsed(); usleep(6000); }
    void p5() {  qDebug() << "p5 at" << time.elapsed(); usleep(3000); }
    void p6() {  qDebug() << "p6 at" << time.elapsed(); usleep(2000); }

private:
    QTime time;
    QTimer t1, t2, t3, t4, t5, t6;
};

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
    Dummy d;
    return app.exec();
}
#include "main.moc"

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You have timers that, in theory at least, will fire together but may be delayed by a few milliseconds while another timer slot is finishing. You will see that in the output.

You can do this particular task with one timer running at 100 milliseconds intervals.

[mahi6a1985]

Hey Thanks a lot Chris, I will implement it in my Application and will let u know. Hope it works in my App too as u suggested.

You can do this particular task with one timer running at 100 milliseconds intervals.

How to implement it in One Timer with 100ms can i know ?