Hello qt forum, I'm currently working on my pre-study at the university and am required to program a logging tool, which has following significant specifications: being able to process logs in 20ms intervals (lower bar) being able to visually show up to 20 Clients logging in tabbed view being able to visually show up to 20 Clients in Floating Windows Now, I've successfully covered the first two parts with Threads processing the logs and signaling the appropriate slots in the GUI Thread for adding the log entry to the appropriate table (QTreeView with Custom Table Model, inherited from QAbstractTableModel). This works fine for tabbed views, as only one tab is visible at all times, so the update of the view doesn't cause the GUI Thread to freeze. But as soon as I have 20 Windows open, the GUI isn't responsive at all anymore. I can't use buffering for the logs, because the logs may arrive at varying intervals and it needs to show arrived logs "instantly". What I considered trying was an updater thread, that would tell the views to draw themselves every 200ms, which for the enduser would still be immediate, but would allow the GUI to have more processing time for responding to UI inputs. This approach improved the responsiveness of the tabs, but didn't much improve the floating windows scenario. I stretched the updating time to 1s and had a significant improvement in the responsiveness of the floating windows, so I think this is related to the view update when beginInsertRows /endInsertRows is called. So my question is: Is there a way you could suggest I could try to improve my responsiveness for 20 Windows being updated almost simultanously? The GUI Thread being the only thread able to update the Views is kind of a bottleneck I'm having a hard time to figure out a way out from my current situation. I tried updating the windows from seperate window threads, but I think because the QTreeView's were created in the GUI Thread, they are connected to the main event loop of the QApplication and I don't really know how I would go about defining an own event loop for the floating windows and their threads if I wanted the event handling to be done in the window threads themselves (ie. when beginInsertRows is called, it would notify only the floating windows UI to redraw). Now, following, are code excerpts of relevant parts of my app: This Code segment is executed in the Client Threads, preparing the log entry, after the log entry is ready, it's signaled to the GUI Thread via client.signalReady(...): QList<QString> CommonLogUtils::prepareLogEntry(RT_Client& client, const REP::PROTO::LogMsg& msg) { QList<QString> row{}; row.append(QString::number(client.itemCount())); //TODO abklären ob wirklich dateLocal hier auto dateWrapper = msg.timestamp().dateLocal(); row.append(CommonStringUtils::prepareTimeString(1900 + dateWrapper.tm_year, dateWrapper.tm_mon, dateWrapper.tm_mday, "-")); row.append(CommonStringUtils::prepareTimeString(dateWrapper.tm_hour, dateWrapper.tm_min, dateWrapper.tm_sec, ":")); row.append(client.getGroupName()); row.append(client.getClientName()); row.append(resolveMessageKind(msg.kind())); row.append(msg.message().c_str()); return row; } void CommonLogUtils::routeOutput(RT_Client& client, const REP::PROTO::LogMsg& msg) { if (client.live()) { client.increaseItemCount(); client.signalReady(prepareLogEntry(client, msg)); } if (client.toParent()) { client.signalParentReady(prepareLogEntry(client, msg)); } if (client.toFile()) { QString filename = client.getClientName() + ".txt"; QFile file{filename}; if (file.open(QIODevice::ReadWrite | QIODevice::Append | QIODevice::Text)) { //TODO adjust output QTextStream stream(&file); stream << msg.timestamp().str().c_str() << " " << client.getGroupName() << " " << client.getClientName() << " " << msg.message().c_str() << endl; } } if (client.toRingFile()) { } } Within the client structure, singalReady looks like this: void RT_Client::signalReady(QList<QString> row) { emit logProcessed(clientName, row); } When the clients first arrive, they send out a register message, before logging, via this register message, the client structures are created and the connections made: if (!modell.getClientsList().contains(msg.client().c_str())) { modell.updateClientList(msg.client().c_str()); modell.getClientsModel()->appendRow(new QStandardItem(msg.client().c_str())); //Add client modell.addClient(msg.id(), msg.client().c_str(), msg.group().c_str()); connect(&modell.getClient(msg.client().c_str()), &RT_Client::logProcessed, this, &RT_Main::handleProcessedLogs, Qt::ConnectionType::QueuedConnection); connect(&modell.getClient(msg.client().c_str()), &RT_Client::logForParentProcessed, this, &RT_Main::handleProcessedLogsForParent, Qt::ConnectionType::QueuedConnection); } So when a client signals "signalReady", it emits a "logProcessed" signal, which is connected to the GUI's handleProcessedLogs slot, which looks like this: void RT_Main::handleProcessedLogs(QString clientName, QList<QString> row) { RT_Client& client = modell.getClient(clientName); client.addLog(row); } Within the addLog function, the entry is added to the model: void RT_Client::addLog(QList<QString> row) const { CustomTableModel * model = static_cast<CustomTableModel *>(table->model()); if (isNewestOnTop) { model->insertOnTop(row); } else { model->appendRow(row); } if (isScrollToBottom) { scroll(); } } When creating a floating window, I switch the connections, as such: void RT_Main::createLogWindow(QString tableName, QPoint startPosition) { if (!subWindowExists(tableName)) { RT_Client& client = modell.getClient(tableName); if (client.getClientName() == RT_Constants::UNSPECIFIED) { client = modell.getGroupClient(tableName); } QThread* thread = new QThread(); RT_LogWindowWorker* worker = new RT_LogWindowWorker(client, false, startPosition); worker->moveToThread(thread); connect(static_cast<CustomQTabWidget*>(modell.getTabWidget()), &CustomQTabWidget::dragFinishedWithSuccess, worker->logWindow, &RT_LogWindow::closeWindow); connect(worker->logWindow, &RT_LogWindow::logWindowClosed, this, &RT_Main::logWindowClosed); connect(this, &RT_Main::windowCloseRequested, worker->logWindow, &RT_LogWindow::closeWindow); disconnect(&client, &RT_Client::logProcessed, this, &RT_Main::handleProcessedLogs); connect(&client, &RT_Client::logProcessed, worker, &RT_LogWindowWorker::handleProcessedLogs); thread->start(); subWindows.insert(tableName, worker); } } The other connection are for drag'n'drop functionality. So what happens is the prepared logs are now sent directly to the worker thread and basically are handled the same way: void RT_LogWindowWorker::handleProcessedLogs(QString clientName, QList<QString> row) const { client.addLog(row); } But because the client and it's QTreeView were created in the GUI Thread, the beginInsertRows signal emitted is processed by the GUI Thread and I'm at square zero. Even if they weren't, I'd need an own event loop in the threads, and I don't know if that's the way to go or how to do that: ie. How to reconnect the beginInsertRows signals How to draw the QTreeView from within the threads If you know of a better solution, I'm all ears for it. I'd really appreciate the help! This is a picture from the problematic situation, even with about 8-10 windows, it laggs horribly(ie. mouse events, click events take a long time to be registered, when dragging windows they don't follow smoothly etc.)

Where exactly do you get that error ? I must say that if somehow has to actually watch 20 live feed widgets at the same time there's likely going to be problem in the workflow. That the architecture allows to take a look at more then one log at a time doesn't sounds unreasonable but 20 in parallel is not something that a human can efficiently parse especially if there's no visual clue as to what he should be looking for (e.g. colour specific entries like blue for info, red for critical etc.) but even so the quantity of information will likely be too much. Can you explain what is monitored like that ?

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Performance issues with multiple visible Windows

Solved General and Desktop

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SGaist
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wrote on 4 May 2017, 19:44 last edited by

#21

One other thing you might want to try: replace your 2 dimensional QList with 2 dimensional QVector.
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4 May 2017, 19:44