I didn't find sufficient answer for this, any suggestion is welcome..
I have a simple MFC single-document app, upon opening file a lengthy computation takes place in separate thread:
BOOL CrhMonkeyDoc::OnOpenDocument(LPCTSTR lpszPathName)
{
if (!CDocument::OnOpenDocument(lpszPathName))
return FALSE;
CMainFrame* pMainFrame = (CMainFrame*)AfxGetMainWnd();
// Start working thread to process the file
m_rhFile.StartParseFile(lpszPathName);
//periodically check progress and update
int progress, lines;
while ((progress = m_rhFile.GetProgress()) < 1000) {
lines = m_rhFile.GetNumLines();
CString strProgress;
strProgress.Format(_T("%d lines, %d percent complete"), lines, progress);
pMainFrame->SetStatusBarText(strProgress);
Sleep(1000);
}
UpdateAllViews(NULL);
}
The thread is started like this:
UINT ParseFileThread(LPVOID Param)
{
RhFile* rhFile = (RhFile*)Param;
rhFile->ParseFile();
return TRUE;
}
int RhFile::StartParseFile(LPCTSTR lpszPathName)
{
m_file.open(lpszPathName);
AfxBeginThread(ParseFileThread, this);
return 0;
}
Initially it does work updating the status bar periodically, but after 10-15 seconds the updates stop and "Not Responding" appears in app title.
I have tried to start the thread at lower priority, and also added periodic SwitchToThread() (always returning 0), and Sleep(50) inside ParseFile(), but it doesn't help.
I guess I am doing something wrong, but can't figure out what
Thanks for reading this!
Related
I want to implement a GUI that receives messages from an external device. The "advancedReceiveExample" is waiting for messages. Once it has received one, it does stuff with it, saves it and terminates.
I want to make my function wait for new messages after receiving one as long as the button is toggled.
I have tried this so far:
void MainWindow::on_pushButton_clicked()
{
if (ui.pushButton->isChecked()) {
ui.pushButton->setText("Stop Receiving");
ui.label_3->setText("Receiving...");
advancedReceiveExample(ui.comboBox->currentIndex() + 1);
}
else
{
ui.pushButton->setText("Start Receiving");
ui.label_3->setText("Not Receiving");
}
}
This works perfectly fine but as mentioned above it only receives one message. If I do that:
void MainWindow::on_pushButton_clicked()
{
if (ui.pushButton->isChecked()) {
ui.pushButton->setText("Stop Receiving");
ui.label_3->setText("Receiving...");
while (1)
{
advancedReceiveExample(ui.comboBox->currentIndex() + 1);
}
}
else
{
ui.pushButton->setText("Start Receiving");
ui.label_3->setText("Not Receiving");
}
}
it blocks the function because the state of the button can only be change after the function "on_pushButton_clicked()" has terminated.
Visual Studio 2019
C/C++
EDIT: Okay, I have understood the problem of blocking the thread. Multithreading might be the right option but I am very unexperienced regarding this topic. The <QThread> could be possible. How would you use it?
Do you have suggestions which other library could be used?
Note QT is event-based. If you keep your computer busy inside some function without returning to the main loop frequently, your GUI will freeze.
What you need to do is slice your action that you want to do into small bits that can repeatedly return to the main loop in order to keep the GUI responsive. (Another method yould be to swap out your action into a separate thread and handle it in parallel, killing the thread when the button is released)
Probably the simplest method to do what you want is with timers that you arm in the PushButton::clicked slot, and then check in the timer event whether the button is still pressed, and, if yes, do a bit of your action, save state and re-arm the timer to have you return.
Something along the lines of the following pseudo code should work and execute what you want to do in slices every 10ms:
MainWindow::onPushButtonClicked () {
// do the action, or, alternatively, start a
// parallel thread that does it
do_a_bit_of_action();
// sets up a timer to call onTimer after 10ms
QTimer::singleShot (10, this, SLOT(onTimer()));
}
MainWindow::onTimer () {
// check if button is still held down
if (pushButton.down) {
// re-arm timer
Timer::singleShot (10, this, SLOT(onTimer()));
// do some more action bits
do_a_bit_of_action();
}
else {
// kill optional background thread here
}
}
You can try it with:
while(ui.pushButton->isChecked()){
*your function*
}
I have developed an OpenGL ES 2.0 win32 application, that works fine in a single thread. But I also understand that UI thread and a rendering thread should be separate.
Currently my game loop looks something like that:
done = 0;
while(!done)
{
msg = GetMessage(..); // getting messages from OS
if(msg == QUIT) // the window has been closed
{
done = 1;
}
DispatchMessage(msg,..); //Calling KeyDown, KeyUp events to handle user input;
DrawCall(...); //Render a frame
Update(..); // Update
}
Please view it as a pseudo code, cause i don't want to bother you with details at this point.
So my next step was to turn done into an std::atomic_int and create a function
RenderThreadMain()
{
while(!done.load())
{
Draw(...);
}
}
and create a std::unique_ptr<std::thread> m_renderThread variable. As you can guess nothing has worked for me so far, so i made my code as stupid and simple as possible in order to make sure i don't break anything with the order i call methods in. So right now my game loop works like this.
done.store(0);
bool created = false;
while(!done)
{
msg = GetMessage(..); // getting messages from OS
if(msg == QUIT) // the window has been closed
{
done.store(1);
}
DispatchMessage(msg,..); //Calling KeyDown, KeyUp events to handle user input;
// to make sure, that my problem is not related to the fact, that i'm rendering too early.
if(!created)
{
m_renderThread = std::make_unique<std::thread>(RenderThreadMain, ...);
created = true;
}
Update(..); // Update
}
But this doesn't work. On every draw call, when i try to somehow access or use my buffers \ textures anything else, i get the GL_INVALID_OPERATION error code.
So my guess would be, that the problem is in me calling glGenBuffers(mk_bufferNumber, m_bufferIds); in the main thread during initialization and then calling glBindBuffer(GL_ARRAY_BUFFER, m_bufferIds[0]); in a render thread during the draw call. (the same applies to every openGL object i have)
But I don't now if i'm right or wrong.
I'm trying to create a "responsive gui", which basically means that I have an app, and on the main window there is a button. After I press this button I want the "progress bar window" to get displayed which will show the progress of the work being done, and of course this work is being done in separate thread.
Unfortunately my approach with starting a new thread in ctor of this progress_bar window doesn't seems to work and I got frozen gui.
Here is the link to this project so you can download it and run without the need for copying and pasting anything: http://www.mediafire.com/?w9b2eilc7t4yux0
Could anyone please tell me what I'm doing wrong and how to fix it?
EDIT
progress_dialog::progress_dialog(QWidget *parent) :
QDialog(parent)
{/*this is this progress dialog which is displayed from main window*/
setupUi(this);
working_thread_ = new Threaded;
connect(working_thread_,SIGNAL(counter_value(int)),progressBar,SLOT(setValue(int)),Qt::QueuedConnection);
working_thread_->start();//HERE I'M STARTING THIS THREAD
}
/*this is run fnc from the threaded class*/
void Threaded::run()
{
unsigned counter = 0;
while(true)
{
emit counter_value(counter);
counter = counter + 1 % 1000000;
}
}
Independently from the fact that tight looping is bad, you should limit the rate at which you make changes to the main GUI thread: the signals from your thread are queued as soon they are emitted on the main thread event loop, and as the GUI can't update that fast, repaint events are queued rather than executed in real time, which freezes the GUI.
And anyways updating the GUI faster than the screen refresh rate is useless.
You could try something like this:
void Threaded::run()
{
QTime time;
time.start();
unsigned counter = 0;
// initial update
emit counter_value(counter);
while(true)
{
counter = (counter + 1) % 1000000;
// 17 ms => ~ 60 fps
if(time.elapsed() > 17) {
emit counter_value(counter);
time.restart();
}
}
}
Do you try to start the thread with a parent object?
I've a for loop that will launch processes in parallel every launched process will return a response back indicating that it is ready. I want to wait for the response and I'll abort if a certain timeout is reached.
Development environment is VS2008
Here is the pseudo code:
void executeCommands(std::vector<Command*> commands)
{
#pragma omp parallel for
for (int i = 0; i < commands.size(); i++)
{
Command* cmd = commands[i];
DWORD pid = ProcessLauncher::launchProcess(cmd->getWorkingDirectory(), cmd->getCommandToExcecute(), cmd->params);
//Should I wait for process to become ready?
if (cmd->getWaitStatusTimeout() > 0)
{
ProcessStatusManager::getInstance().addListener(*this);
//TODO: emit process launching signal
//BEGINNING OF QUESTION
//I don't how to do this part.
//I might use QT's QWaitCondition but if there is another solution in omp
//I'd like to use it
bool timedOut;
SOMEHANDLE handle = Openmp::waitWithTimeout(cmd->getWaitStatusTimeout(), &timedOut);
mWaitConditions[pid]) = handle;
//END OF QUESTION
if (timedOut)
{
ProcessStatusManager::getInstance().removeListener(*this);
//TODO: kill process
//TODO: emit fail signal
}
else
{
//TODO: emit process ready signal
}
}
else
{
//TODO: emit process ready signal
}
}
}
void onProcessReady(DWORD sourceProcessPid)
{
ProcessStatusManager::getInstance().removeListener(*this);
SOMEHANDLE handle = mWaitConditions[sourceProcessPid];
if (mWaitConditions[sourceProcessPid] != 0)
{
Openmp::wakeAll(handle);
}
}
As the comment above pointed out, Michael Suess did present a paper on adding this functionality to OpenMP. He is the last of several people that have proposed adding some type of wait function to OpenMP. The OpenMP language committee has taken the issue up several times. Each time it has been rejected because there are other ways to do this function already. I don't know Qt, but as long as the functions it provides are thread safe, then you should be able to use them.
I think I am making a simple mistake, but since I noticed there are many boost experts here, I thought I would ask for help.
I am trying to use boost threads(1_40) on windows xp. The main program loads a dll, starts the thread like so (note this is not in a class, the static does not mean static to a class but private to the file).
static boost::thread network_thread;
static bool quit = false;
HANDLE quitEvent;
//some code omitted for clarity, ask if you think it would help
void network_start()
{
HANDLE *waitHandles = (HANDLE*)malloc(3 * sizeof(HANDLE));
waitHandles[0] = quitEvent;
waitHandles[1] = recvEvent;
waitHandles[2] = pendingEvent;
do {
//read network stuff, or quit event
dwEvents =WaitForMultipleObjects(3, waitHandles, FALSE, timeout);
} while (!quit)
}
DllClass::InitInstance()
{
}
DllClass::ExportedFunction()
{
network_thread = boost::thread(boost::bind<void>(network_start));
}
DllClass::ExitInstance()
{
//signal quit (which works)
quit = true;
SetEvent(QuitEvent);
//the following code is slightly verbose because I'm trying to figure out what's wrong
try {
if (network_thread.joinable() ) {
network_thread.join();
} else {
TRACE("Too late!");
}
} catch (boost::thread_interrupted&) {
TRACE("NET INTERRUPTED");
}
}
The problem is that the main thread is hanging on the join, and the network thread is hanging at the end of _endthreadex. What am I misunderstanding?
You are not supposed to create/end threads in InitInstance/ExitInstance,
see http://support.microsoft.com/default.aspx?scid=kb;EN-US;142243 for more info. Also, see http://msdn.microsoft.com/en-us/library/ms682583%28VS.85%29.aspx about DllMain in general.