c++ - Qt slot from thread called more than once -

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• slot being called multiple times every time signal emitted 1 answer
• qt signals , slot connected twice… happens? 3 answers

i have created class calculationmanager has public slot process() emitting signal finished().

void calculationmanager::process() {     cout << "calc fft: process()" << endl;     ...     emit finished(); } 

this used qthread gui (calculationmanager qscopedpointer)

void mainwindow::on_pushbuttonstartfft_clicked() {     cout << "on_pushbuttonstartfft_clicked()" << endl;      ...     calculationmanager->movetothread(thread);      connect(thread, signal (started()), calculationmanager.data(), slot (process()));     connect(calculationmanager.data(), signal (finished()), thread, slot (quit()));     connect(calculationmanager.data(), signal (finished()), this, slot (getresultsandplot()));      cout << "fft thread started." << endl;     thread->start(); } 

with slot plots

void mainwindow::getresultsandplot() {     fftaction doshift = static_cast<fftaction>(calculationmanager->shiftbeforefft());      updateplotdata(ui->qplot1, calculationmanager->data(doshift) );     cout << "update plots" << endl; } 

at startup of gui function called. , output expected:

on_pushbuttonstartfft_clicked() fft thread started. calc fft: process() update plots 

however every further click on buttons calls process multiple times , getresultsandplot() more often. have not clue why happens. how can debug or solve ?

on_pushbuttonstartfft_clicked() fft thread started. calc fft: process() calc fft: process() update plots update plots update plots update plots on_pushbuttonstartfft_clicked() fft thread started. calc fft: process() calc fft: process() calc fft: process() update plots update plots update plots update plots update plots update plots update plots update plots update plots 

every time click button, create connections

connect(thread, signal (started()), calculationmanager.data(), slot (process())); connect(calculationmanager.data(), signal (finished()), thread, slot (quit())); connect(calculationmanager.data(), signal (finished()), this, slot (getresultsandplot())); 

so, after first click there 1 connection , slot process() called once. after second click there 2 connections , slot called twice. , on. make connections outside slot on_pushbuttonstartfft_clicked().