QObject: Cannot create children for a parent that is in a different thread-蒲公英云

QObject: Cannot create children for a parent that is in a different thread

女爷i 2022-09-04 02:53 27阅读 0赞

故障程序

#include "mythread.h"
#include <QDebug>
MyThread::MyThread(QThread *parent) : QThread(parent)
{ 
    ce = new CommandExecutor("ls /");
    connect(ce, SIGNAL(finishedEvent()), this, SLOT(onFinished()));
}
void MyThread::run()
{
    qDebug() << "start thread";    
    ce->start();
    qDebug() << "exec";
    exec();
    qDebug() << "exec finished";
}
void MyThread::onFinished()
{
    qDebug() << "onFinished";
    if(ce){
        ce->deleteLater();
    }
}

运行时报错

2021-08-10 15:11:50:331[7f2dc67aa700]WARN: QObject: Cannot create children for a parent that is in a different thread.
(Parent is QProcess(0x13466a0), parent's thread is QThread(0x1304480), current thread is MyThread(0x1349cf0) ((null):0, (null))

注意，CommandExecutor是基于QProcess封装的命令执行器，改为在run()方法中初始化CommandExecutor实例，使得新实例归属当前线程。

新代码

#include "mythread.h"
#include <QDebug>
MyThread::MyThread(QThread *parent) : QThread(parent)
{
}
void MyThread::run()
{
    qDebug() << "start thread";
    ce = new CommandExecutor("ls /");
    connect(ce, SIGNAL(finishedEvent()), this, SLOT(onFinished()));
    ce->start();
    qDebug() << "exec";
    exec();
    qDebug() << "exec finished";
}
void MyThread::onFinished()
{
    qDebug() << "onFinished";
    if(ce){
        ce->deleteLater();
    }
}

运行结果

15:18:09: Starting /home/yeqiang/code/build-qt-training-Desktop-Debug/qt-training ...
2021-08-10 15:18:09:900[7f8a1610d700]DEBUG: start thread (../qt-training/mythread.cpp:16, virtual void MyThread::run())
2021-08-10 15:18:09:900[7f8a1610d700]DEBUG: "ls /" (../qt-training/commandexecutor.cpp:6, CommandExecutor::CommandExecutor(QString, QObject*))
2021-08-10 15:18:09:900[7f8a1610d700]DEBUG: "ls /"  started (../qt-training/commandexecutor.cpp:20, void CommandExecutor::start())
2021-08-10 15:18:09:900[7f8a1610d700]DEBUG: exec (../qt-training/mythread.cpp:20, virtual void MyThread::run())
2021-08-10 15:18:09:901[7f8a1610d700]DEBUG: "stdout: bin\nboot\nDesktop\ndev\netc\nhome\nlib\nlib32\nlib64\nlibx32\nlost+found\nmedia\nmnt\nopt\nproc\nroot\nrun\nsbin\nsnap\nsrv\nsys\nTemplates\ntmp\nusr\nvar\nVirtualBox VMs\n" (../qt-training/commandexecutor.cpp:31, void CommandExecutor::onReadStandardOutput())
2021-08-10 15:18:09:901[7f8a1610d700]DEBUG: finished 0 (../qt-training/commandexecutor.cpp:44, void CommandExecutor::onFinished(int, QProcess::ExitStatus))
2021-08-10 15:18:09:901[7f8a1610d700]DEBUG: emit finishedEvent (../qt-training/commandexecutor.cpp:46, void CommandExecutor::onFinished(int, QProcess::ExitStatus))
2021-08-10 15:18:09:903[7f8a17dd6240]DEBUG: onFinished (../qt-training/mythread.cpp:27, void MyThread::onFinished())