Qt Forum

    • Login
    • Search
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Groups
    • Search
    • Unsolved

    Solved QMYSQL SIGSEGV

    General and Desktop
    3
    21
    3106
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • C
      ckvsoft last edited by

      Hallo

      I got some failures with QMYSQL (QSQLITE will work)

      My connection will be

      if (dbType == "QSQLITE") {
                  currentConnection = QSqlDatabase::addDatabase("QSQLITE", "CN");
                  currentConnection.setDatabaseName(QString(dataDir + "/%1-%2.db").arg(date.year()).arg(basename));
              } else if (dbType == "QMYSQL") {
                  QString userName = settings.value("DB_userName", "QRK").toString();
                  QString password = settings.value("DB_password", "").toString();
                  QString hostName = settings.value("DB_hostName", "localhost").toString();
           
                  currentConnection = QSqlDatabase::addDatabase("QMYSQL", "CN");
                  currentConnection.setHostName(hostName);
                  currentConnection.setUserName(userName);
                  currentConnection.setPassword(password);
                  currentConnection.setConnectOptions("MYSQL_OPT_RECONNECT=1;MYSQL_OPT_CONNECT_TIMEOUT=86400;MYSQL_OPT_READ_TIMEOUT=60");
              }
           
              bool ok = currentConnection.open();
      
      

      When i was connected and to a simple query i got, but not allways a SIGSEGV. When i remove the connection options i got "Lost connection to MySQL server during query"
      no matter if MySQL Server is localhost or any Server on the Internet.

      Yes, i search but found no solution. What can i do false?

      OS: Linux Ubuntu (16.04 and 17.10) Server MariaDB from the Ubuntu Package

      A Simply Query which returns one record and the Database holds max. 10 Entries.

          QSqlDatabase dbc = QSqlDatabase::database("CN");
              QSqlQuery query(dbc);
           
              query.prepare("SELECT strValue FROM globals WHERE name='shopName'");
              query.exec();
              query.next();
           
              name = query.value(0).toString();
      
      

      thx Chris

      1 Reply Last reply Reply Quote 0
      • SGaist
        SGaist Lifetime Qt Champion last edited by

        Hi,

        What version of Qt are you using ?

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

        1 Reply Last reply Reply Quote 0
        • C
          ckvsoft last edited by ckvsoft

          Hi
          Oh, sorry
          QT5.9.1 from Ubuntu 17.10

          But also with QT5.6 on Ubuntu 16.04
          lg chris

          1 Reply Last reply Reply Quote 0
          • SGaist
            SGaist Lifetime Qt Champion last edited by

            Can you show the stack trace ?

            By the way, 5.9.4 just got released, it's worth checking if it behaves better.

            Interested in AI ? www.idiap.ch
            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

            1 Reply Last reply Reply Quote 0
            • C
              ckvsoft last edited by

              Hi
              Hope this helps ...

              signal 11 (Speicherzugriffsfehler), address is 0x1b0 from 0x7fffcff1e5ea
              [bt]: (1) /usr/lib/x86_64-linux-gnu/libmysqlclient.so.20(+0x375ea) [0x7fffcff1e5ea]
              [bt]: (2) /usr/lib/x86_64-linux-gnu/libmysqlclient.so.20(+0x375ea) [0x7fffcff1e5ea]
              [bt]: (3) /usr/lib/x86_64-linux-gnu/libmysqlclient.so.20(+0x3865c) [0x7fffcff1f65c]
              [bt]: (4) /usr/lib/x86_64-linux-gnu/libmysqlclient.so.20(+0x2cbdc) [0x7fffcff13bdc]
              [bt]: (5) /usr/lib/x86_64-linux-gnu/libmysqlclient.so.20(+0x27516) [0x7fffcff0e516]
              [bt]: (6) /usr/lib/x86_64-linux-gnu/libmysqlclient.so.20(mysql_stmt_prepare+0x96) [0x7fffcff0e8a6]
              [bt]: (7) /usr/lib/x86_64-linux-gnu/qt5/plugins/sqldrivers/libqsqlmysql.so(+0xc70c) [0x7fffd050370c]
              [bt]: (8) /usr/lib/x86_64-linux-gnu/libQt5Sql.so.5(_ZN10QSqlResult11savePrepareERK7QString+0x200) [0x7ffff64260d0]
              [bt]: (9) /usr/lib/x86_64-linux-gnu/libQt5Sql.so.5(_ZN9QSqlQuery7prepareERK7QString+0x208) [0x7ffff6417008]
              [bt]: (10) /home/chris/Dokumente/projects/qt/build-QRK-Desktop-Debug/qrkcore/libQrkCore.so.1(_ZN8Database17getCashRegisterIdEv+0x80) [0x7ffff791f2aa]
              [bt]: (11) /home/chris/Dokumente/projects/qt/build-QRK-Desktop-Debug/qrkcore/libQrkCore.so.1(_ZN14VersionChecker10getVersionEv+0x25e) [0x7ffff7992e6a]
              [bt]: (12) /home/chris/Dokumente/projects/qt/build-QRK-Desktop-Debug/qrkcore/libQrkCore.so.1(_ZN9QtPrivate11FunctorCallINS_11IndexesListIJEEENS_4ListIJEEEvM14VersionCheckerFvvEE4callES7_PS5_PPv+0x7a) [0x7ffff7993e80]
              [bt]: (13) /home/chris/Dokumente/projects/qt/build-QRK-Desktop-Debug/qrkcore/libQrkCore.so.1(_ZN9QtPrivate15FunctionPointerIM14VersionCheckerFvvEE4callINS_4ListIJEEEvEEvS3_PS1_PPv+0x42) [0x7ffff7993e03]
              [bt]: (14) /home/chris/Dokumente/projects/qt/build-QRK-Desktop-Debug/qrkcore/libQrkCore.so.1(_ZN9QtPrivate11QSlotObjectIM14VersionCheckerFvvENS_4ListIJEEEvE4implEiPNS_15QSlotObjectBaseEP7QObjectPPvPb+0x6c) [0x7ffff7993d6d]
              [bt]: (15) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN11QMetaObject8activateEP7QObjectiiPPv+0x97f) [0x7ffff5f729ff]
              [bt]: (16) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN6QTimer7timeoutENS_14QPrivateSignalE+0x37) [0x7ffff5f7f3b7]
              [bt]: (17) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN6QTimer10timerEventEP11QTimerEvent+0x28) [0x7ffff5f7f718]
              [bt]: (18) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN7QObject5eventEP6QEvent+0x9b) [0x7ffff5f7340b]
              [bt]: (19) /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5(_ZN19QApplicationPrivate13notify_helperEP7QObjectP6QEvent+0x9c) [0x7ffff6f0746c]
              [bt]: (20) /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5(_ZN12QApplication6notifyEP7QObjectP6QEvent+0x2a4) [0x7ffff6f0ed34]
              [bt]: (21) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent+0x118) [0x7ffff5f43de8]
              [bt]: (22) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN14QTimerInfoList14activateTimersEv+0x40e) [0x7ffff5f9b91e]
              [bt]: (23) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(+0x2e20e1) [0x7ffff5f9c0e1]
              [bt]: (24) /lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_dispatch+0x2e7) [0x7ffff2a69fb7]
              [bt]: (25) /lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x4b1f0) [0x7ffff2a6a1f0]
              [bt]: (26) /lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_iteration+0x2c) [0x7ffff2a6a27c]
              [bt]: (27) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE+0x5f) [0x7ffff5f9c47f]
              [bt]: (28) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE+0x13a) [0x7ffff5f41e3a]
              [bt]: (29) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(_ZN7QThread4execEv+0x6a) [0x7ffff5d613ca]
              [bt]: (30) /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(+0xac29d) [0x7ffff5d6629d]
              [bt]: (31) /lib/x86_64-linux-gnu/libpthread.so.0(+0x77fc) [0x7ffff5aa27fc]
              [bt]: (32) /lib/x86_64-linux-gnu/libc.so.6(clone+0x3f) [0x7ffff5232b5f]
              

              lg Chris

              JonB 1 Reply Last reply Reply Quote 0
              • JonB
                JonB @ckvsoft last edited by

                @ckvsoft
                At what precise point from your code does this SEGV occur? It looks like it's just in your query.prepare() statement, without even getting as far as the execute, is that what you find stepping through?

                Also, why do you think you're having to specify all those timeout/reconnect options, else you say it loses connection. It shouldn't be losing connection anyway. Unless that's an artefact of an underlying problem which sometimes SEGVs and sometimes doesn't...

                1 Reply Last reply Reply Quote 1
                • C
                  ckvsoft last edited by ckvsoft

                  @JonB
                  This was a test while without these Options i got a "Lost connection to MySQL server during query" without SEGV but the Query was not made. The Server is running normaly without troubles Its a TCP connection while not on the same machine. I test an other Server with do the same. Tomorow i will test a localhost machine.

                  Its not allways the same query and not allways the prepare. Sometimes it is by "QSqlQuery query(dbc)" and somtime by the exec.

                  1 Reply Last reply Reply Quote 0
                  • SGaist
                    SGaist Lifetime Qt Champion last edited by

                    What is that qrkcore library you are using ?

                    Interested in AI ? www.idiap.ch
                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                    C 1 Reply Last reply Reply Quote 0
                    • C
                      ckvsoft @SGaist last edited by

                      @SGaist
                      This is a Part of my Application . Why?

                      1 Reply Last reply Reply Quote 0
                      • SGaist
                        SGaist Lifetime Qt Champion last edited by

                        Well... To know whether it's an external library you are using or something you are implementing.

                        Do you have the same crash if you implement just a minimal application that connects to the database and does the queries ?

                        Interested in AI ? www.idiap.ch
                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                        1 Reply Last reply Reply Quote 0
                        • C
                          ckvsoft last edited by

                          @SGaist
                          I will try this at weekend. Also i will test if MySQL and MariaDB has the same. The queries where made from the library. Thx for the time

                          1 Reply Last reply Reply Quote 0
                          • C
                            ckvsoft last edited by ckvsoft

                            Hi
                            I connect to a localhost mysql server and it seems to work. When i has running in the background some sql queries and i do at the same time from other window with the same connection any query it works.

                            When i connect to a server via TCP it will crash.
                            Edit: Its also with localhost, but the time is a bit longer ;(

                            1 Reply Last reply Reply Quote 0
                            • SGaist
                              SGaist Lifetime Qt Champion last edited by

                              Can you trigger also that when using an application that's not using the QSql** classes ?

                              Interested in AI ? www.idiap.ch
                              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                              1 Reply Last reply Reply Quote 0
                              • C
                                ckvsoft last edited by

                                I think i have found a solution ;-) Some Test will be good. I will enhance my tests.
                                The Idea i found by reading http://doc.qt.io/qt-5/threads-modules.html

                                Just my Application worked since 2015 with QSQLITE without troubles. But some users will also use MySQL.

                                For the solution i have adapted a database manager for my requirement.

                                1 Reply Last reply Reply Quote 0
                                • SGaist
                                  SGaist Lifetime Qt Champion last edited by

                                  So you're using multiple threads to write to your database ?

                                  Interested in AI ? www.idiap.ch
                                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                  C 1 Reply Last reply Reply Quote 0
                                  • C
                                    ckvsoft @SGaist last edited by ckvsoft

                                    @SGaist
                                    Yes. I Import JSON Files with an Import Walter Thread. Wenn a File is copied in a Directory it will Import and created new sql entries.
                                    Nur Why SQlite has no Troubles?
                                    I will also Move long Working Stuff to thread

                                    Ob they GUI you also can do some queries by clicking Buttons

                                    1 Reply Last reply Reply Quote 0
                                    • SGaist
                                      SGaist Lifetime Qt Champion last edited by

                                      I'd say pure luck.

                                      Are you creating one connection per thread like suggested in the documentation ?

                                      Interested in AI ? www.idiap.ch
                                      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                      1 Reply Last reply Reply Quote 1
                                      • C
                                        ckvsoft last edited by ckvsoft

                                        @SGaist
                                        Yes. The DatabaseManager save the connections per thread into a

                                        QHash<QThread*, QHash<QString, QSqlDatabase> > 
                                        
                                        

                                        I have only one thread at a time wich write to the database. All others max. 4 to only select
                                        Sorry for my "Austrian English" ;-)

                                        1 Reply Last reply Reply Quote 0
                                        • SGaist
                                          SGaist Lifetime Qt Champion last edited by

                                          Can you show how your are setting up the connections ?

                                          Interested in AI ? www.idiap.ch
                                          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                          1 Reply Last reply Reply Quote 1
                                          • C
                                            ckvsoft last edited by ckvsoft

                                            @SGaist

                                            The first connection is in my first post
                                            Than for every connection i call

                                            QSqlDatabase dbc = DatabaseManager::database("CN");
                                            QSqlQuery query(dbc)
                                            .
                                            .
                                            

                                            .

                                            #include "databasemanager.h"
                                            
                                            #include <QSqlDatabase>
                                            #include <QMutexLocker>
                                            #include <QThread>
                                            #include <QSqlError>
                                            #include <QDebug>
                                            
                                            QMutex DatabaseManager::s_databaseMutex;
                                            QHash<QThread*, QHash<QString, QSqlDatabase> > DatabaseManager::s_instances;
                                            
                                            QSqlDatabase DatabaseManager::database(const QString& connectionName)
                                            {
                                                QMutexLocker locker(&s_databaseMutex);
                                                QThread *thread = QThread::currentThread();
                                            
                                                // if we have a connection for this thread, return it
                                                QHash<QThread*, QHash<QString, QSqlDatabase> >::Iterator it_thread = s_instances.find(thread);
                                                if (it_thread != s_instances.end()) {
                                                    QHash<QString, QSqlDatabase>::iterator it_conn = it_thread.value().find(connectionName);
                                                    if (it_conn != it_thread.value().end()) {
                                                        QSqlDatabase connection = it_conn.value();
                                            //            qDebug() << "Function Name: " << Q_FUNC_INFO << " found SQL connection instances Thread: " << thread->currentThreadId() << " Name: " << connectionName;
                                                        if (connection.isValid())
                                                            return it_conn.value();
                                                    }
                                                }
                                            
                                                // otherwise, create a new connection for this thread
                                                QSqlDatabase connection = QSqlDatabase::cloneDatabase(
                                                                              QSqlDatabase::database(connectionName),
                                                                              QString("%1_%2").arg(connectionName).arg((int)thread));
                                            
                                                // open the database connection
                                                // initialize the database connection
                                                if (!connection.open()) {
                                                    // Todo: Exeption Handling
                                                    qCritical() << "Function Name: " << Q_FUNC_INFO << connection.lastError().text();
                                                    return connection;
                                                }
                                            
                                                qDebug() << "Function Name: " << Q_FUNC_INFO << " new SQL connection instances Thread: " << thread->currentThreadId() << " Name: " << connectionName;
                                            
                                                s_instances[thread][connectionName] = connection;
                                                return connection;
                                            }
                                            
                                            #ifndef DATABASEMANAGER_H
                                            #define DATABASEMANAGER_H
                                            
                                            #include "qrkcore_global.h"
                                            
                                            #include <QMutex>
                                            #include <QHash>
                                            #include <QSqlDatabase>
                                            
                                            class QThread;
                                            
                                            class QRK_EXPORT DatabaseManager
                                            {
                                                public:
                                                    static QSqlDatabase database(const QString& connectionName = QLatin1String(QSqlDatabase::defaultConnection));
                                                private:
                                                    static QMutex s_databaseMutex;
                                                    static QHash<QThread*, QHash<QString, QSqlDatabase>> s_instances;
                                            
                                            };
                                            
                                            #endif // DATABASEMANAGER_H
                                            

                                            I found the code and adapted it for my requirement.

                                            1 Reply Last reply Reply Quote 0
                                            • First post
                                              Last post