Qt console application leaves terminal open on termination

SPlatten

@jsulm , its a bit like a web-server, multiple clients, each client (module) does not monopolise the application by holding up communications, so to keep it as responsive as possible each client gets it's own thread.

SPlatten

@SPlatten , I've re-written the launch function:

QProcess* clsScriptHelper::pLaunch(QString strApp, QStringList& slstArgs) {
    QString strFullPath(clsDebugService::strGetUserFolder(strApp));
    qdbg() << "Checking for PID for: " << strFullPath;
    QProcess* pModule = nullptr;
    qint64 int64PID;
    if ( blnGetPID(strFullPath, int64PID) == true ) {
    //Process already running, no action required
    } else {
        int intLastSep = strFullPath.lastIndexOf(QDir::separator());
        qdbg() << "Process is NOT running, launching";

        if ( intLastSep > 0 ) {
            QString strName = strFullPath.mid(intLastSep + 1)
                   ,strPath = strFullPath.mid(0, intLastSep + 1);
            pModule = new QProcess(this);
            pModule->setArguments(slstArgs);
            pModule->setWorkingDirectory(strPath);
            pModule->setProgram(strName);
            pModule->start();
            int64PID = pModule->processId();

            if ( int64PID == 0 ) {
                delete pModule;
                pModule = nullptr;
            }
        }
    }
    if ( int64PID > 0 ) {
        qdbg() << "Process: " << strFullPath << " started, PID: " << QString::number(int64PID);
    }
    return pModule;
}

This works a lot better and now the child process is terminated and the terminal window closes when the main application terminates, however I am still seeing in the Application Output:

W00000000000000000014:QObject: Cannot create children for a parent that is in a different thread.
W00000000000000000015:(Parent is clsScriptHelper(0x10320da10), parent's thread is QThread(0x10320aad0), current thread is clsThread(0x10325d1a0)

Is there any way to avoid/prevent this?

jsulm

@SPlatten said in Qt console application leaves terminal open on termination:

Is there any way to avoid/prevent this?

Yes, doing multithreading in a proper way. As I wrote before: you are doing something wrongly somewhere in your code. And the warning even tells you what: you are using an objects as parent for another object which lives in another thread.
You should read this: https://doc.qt.io/qt-5/qobject.html#thread-affinity

SPlatten

@jsulm, the difficulty is that the method of calling the launch function is from an exported / exposed (not sure of correct terminology) API call from the C++ to JavaScript:

Q_INVOKABLE QJsonObject use(QJsonValue strModule);

In the JavaScript:

xmleng.use("mdFileIO");

Where xmleng is exposed to the JavaScript by the engine:

    const QString strXMLEngine("xmleng");

    if ( objGlobal.hasProperty(strXMLEngine) == false ) {
        clsScriptHelper* pScriptHlpr = clsScriptHelper::pobjGetInstance();

        if ( pScriptHlpr != nullptr ) {
            QJSValue result = pobjScriptEng->newQObject(pScriptHlpr);
            objGlobal.setProperty(strXMLEngine, result);
        }
    }

The use function in C++:

/**
 * @brief clsScriptHelper::use
 * @param strModule : Name of the module to use
 * @return JSON object containing pass on when using the module
 */
QJsonObject clsScriptHelper::use(QJsonValue strModule) {   
    clsXMLnode* pobjRoot = clsXMLnode::spobjGetRoot();
    Q_ASSERT_X(pobjRoot!=nullptr, "clsScriptHelper::use"
                                , "pobjRoot is NULL!");
    QString strModulesPath = pobjRoot->strGetAttribute(clsXMLnode::mscszAttrModules)
           ,strModuleName = strModule.toString();
//Is module already loaded?
    mpModules::iterator itrModule;
    QJsonObject objModule;
    QStringList slstSlot;

    if ( clsScriptHelper::blnGetModule(strModuleName, &itrModule) == true ) {
//Module already loaded, get the process id
        objModule = itrModule->second;
    } else {
//Module not loaded yet, attempt to start the module
        QString strFullPath(strModulesPath + strModule.toString());
        QStringList slstArgs;
        slstArgs << QString::number(clsSocketServer::mscuint16port);
        slstArgs << QString::number(clsSocketServer::uint16NextModulePort());
        slstArgs << QString::number(QCoreApplication::applicationPid());
        QProcess* pProcess;
        if (  (pProcess = pLaunch(strFullPath, slstArgs)) != nullptr ) {
//Module has been successfully started, save its PID
            qint64 int64PID = pProcess->processId();
            objModule.insert(clsJSON::mscszModule, strModule);
            objModule.insert(clsScriptHelper::mscszPID, QJsonValue(int64PID));
            msmpModules.insert(std::make_pair(strModuleName, objModule));
//Register JSON decoders
            QString strKey(strModule.toString() + clsJSON::msccColon + QString(clsJSON::mscszCmdHB));
            clsJSON::registerDecoder(strKey, blnDecodeHeartbeat);
        }
    }
    return objModule;
}

SPlatten

@jsulm, fixed now, the solution was to from "this" when creating the process.