<![CDATA[Using QTextStream leads to memory leak]]>Hi
I'm using QTextStream for writing received data from network in a text file.
But it leads to memory leak!
I don't know how to solve the problem.
when I uncomment the return, memory leak disappears.

QVector<QFile*> fileList_rdu_1;
QByteArray filesIDList_rdu_1;
QTextStream logWrite;
***********************************

void Logger::readyRead(QString frame, char ID, QString IP, QString logType)
{
    //
    // return;

    if(logType == "Log_S" && ID < 24)
    {
        if(fileList_rdu_1.count() == 0)
        {
            return;
        }
        else if(filesIDList_rdu_1.contains(char(ID)))
        {
            logWrite.setDevice(fileList_rdu_1[filesIDList_rdu_1.indexOf(char(ID))]);
            logWrite << QDateTime::currentDateTime().toString("hh:mm:ss.zzz ") + frame + "Switch_IP:" + IP + " " + logType + "\n";
            //
            fileList_rdu_1[filesIDList_rdu_1.indexOf(char(ID))]->flush();
        }
    }
}
****************************
I have tried this also:
{
        QTextStream out(fileList[filesIDList.indexOf(char(ID))]);
        out.setCodec("UTF-8");
        out << QDateTime::currentDateTime().toString("hh:mm:ss.zzz ") + frame + "Switch_IP:" + IP + " "  + logType + "\n";
        //
        fileList[filesIDList.indexOf(char(ID))]->flush();
}

thanks.

]]>https://forum.qt.io/topic/132399/using-qtextstream-leads-to-memory-leakRSS for NodeSun, 12 Apr 2026 22:24:58 GMTTue, 30 Nov 2021 07:17:11 GMT60<![CDATA[Reply to Using QTextStream leads to memory leak on Sun, 05 Dec 2021 05:35:09 GMT]]>Hi
Thanks @jsulm , @Bonnie , @JonB , @mranger90

I solved the problem this way:

QVector<QTextStream*> textStreamList_rdu_1;

****

QTextStream *out = textStreamList_rdu_1[filesIDList_rdu_1.indexOf(char(ID))];
(*out) << QDateTime::currentDateTime().toString("hh:mm:ss.zzz ") + frame + "Switch_IP:" + IP + " " + logType << &Qt::endl(*out);

*** // Close files and delete pointers
for(int i = 0; i < fileList_rdu_1.size(); i++)
{
    fileList_rdu_1[i]->close();
   delete textStreamList_rdu_1[i];
}
//
fileList_rdu_1.clear();
textStreamList_rdu_1.clear();

The main problem was when the opened file not closed immediately, the memory started to increase! was so strange.

]]>https://forum.qt.io/post/693288https://forum.qt.io/post/693288Sun, 05 Dec 2021 05:35:09 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 16:38:06 GMT]]>@Jamshid said in Using QTextStream leads to memory leak:

filesIDList_rdu_1

One thing I'd check is to protect this with a mutex or something to make sure that you're not re-entering and causing some unexpected behavior from the setDevice

]]>https://forum.qt.io/post/692494https://forum.qt.io/post/692494Tue, 30 Nov 2021 16:38:06 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 10:02:56 GMT]]>I would reduce your program to a minimum to see behaviour, and then build back up from there. For example, try nothing but QTextStream out(fileList[filesIDList.indexOf(char(ID))]);, don't even use that out variable, no actual logging, how does that behave? If that does not show your memory increase, re-introduce individual lines.

]]>https://forum.qt.io/post/692412https://forum.qt.io/post/692412Tue, 30 Nov 2021 10:02:56 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 09:42:16 GMT]]>Maybe I should try C++ FILE instead of QFile

]]>https://forum.qt.io/post/692402https://forum.qt.io/post/692402Tue, 30 Nov 2021 09:42:16 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 09:41:42 GMT]]>@Bonnie Did not work!

]]>https://forum.qt.io/post/692401https://forum.qt.io/post/692401Tue, 30 Nov 2021 09:41:42 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 08:39:12 GMT]]>@Bonnie I'll try that, thanks.

]]>https://forum.qt.io/post/692378https://forum.qt.io/post/692378Tue, 30 Nov 2021 08:39:12 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 08:37:46 GMT]]>@jsulm Writing in a normal text file.
fileList_rdu_1 range is from 1 to 17.
Yes you are right, I'm not checking that!

]]>https://forum.qt.io/post/692377https://forum.qt.io/post/692377Tue, 30 Nov 2021 08:37:46 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 08:18:37 GMT]]>How about replace the "\n" with Qt::endl? like

logWrite << QDateTime::currentDateTime().toString("hh:mm:ss.zzz ") << frame << "Switch_IP:" << IP << " " << logType << Qt::endl;

That would flush the stream.

]]>https://forum.qt.io/post/692373https://forum.qt.io/post/692373Tue, 30 Nov 2021 08:18:37 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 08:09:19 GMT]]>@Jamshid In what kind of files are you writing? Normal files? You should use some tool to check where exactly memory is consumed.
How many entries do you have in fileList_rdu_1?
By the way: you are NOT checking whether filesIDList_rdu_1.indexOf(char(ID)) is out of bounds in fileList_rdu_1!

]]>https://forum.qt.io/post/692369https://forum.qt.io/post/692369Tue, 30 Nov 2021 08:09:19 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 08:00:20 GMT]]>The RAM usage of software in Task Manager increases from 22 MB to almost 1500MB over time (a few hours) and the program crashes!

]]>https://forum.qt.io/post/692365https://forum.qt.io/post/692365Tue, 30 Nov 2021 08:00:20 GMT<![CDATA[Reply to Using QTextStream leads to memory leak on Tue, 30 Nov 2021 07:26:17 GMT]]>@Jamshid How did you verify that you have a memory leak?

]]>https://forum.qt.io/post/692356https://forum.qt.io/post/692356Tue, 30 Nov 2021 07:26:17 GMT