我正在使用QProcess从libs3运行s3程序。
QString S3::runS3(const QStringList &args, const QByteArray &data)
{
QProcess s3;
QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
env.insert("S3_ACCESS_KEY_ID", "xxx");
env.insert("S3_SECRET_ACCESS_KEY", "xxx");
s3.setProcessEnvironment(env);
s3.start("s3", args);
if (!s3.waitForStarted())
{
qWarning() << "Could not start the s3 process!";
return QString();
}
if (data.size() > 0)
{
s3.write(data);
s3.closeWriteChannel();
}
if (!s3.waitForFinished())
{
qWarning() << "The s3 process did not complete successfully";
if (s3.error() == QProcess::Timedout)
{
qWarning() << "The s3 process took too long to execute";
}
qWarning() << QString(s3.readAllStandardOutput());
qWarning() << QString(s3.readAllStandardError());
qWarning() << s3.exitCode();
qWarning() << s3.exitStatus();
qWarning() << s3.pid();
return QString();
}
return QString(s3.readAll());
}
但是，每次运行此代码时，waitForFinished方法都会等待整整30秒，我会将其输出：
The s3 process did not complete successfully
The s3 process took too long to execute
"1474272 bytes remaining (1% complete) ...
1457888 bytes remaining (2% complete) ...
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"
""
0
0
18506
QProcess: Destroyed while process is still running.
我可以看到，在waitForFinished超时之前，S3进程显然没有在Activity Monitor.app中运行。发生了什么事？
答案 0 :(得分：1)
这个问题的原因是我没有正确地将Qt的事件循环与Wt集成，所以当我调用这些函数时它没有运行 - QProcess恰好需要事件循环。
答案 1 :(得分：0)
QProcess：在进程仍在运行时销毁。
这只是意味着QProcess实例超出范围并在没有正确终止的情况下被销毁，而不是“Qt认为进程在退出后正在运行”。
您可以尝试将QProcess::stateChanged(QProcess::ProcessState newState)信号连接到某个QObject插槽，以确定“Qt认为某个进程是否正在运行”。
对于您的实际问题，我认为s3进程（而不是QProcess）只需要超过30秒，这是函数签名中的默认值：
bool QProcess::waitForFinished ( int msecs = 30000 )
给它一些时间或尝试传递-1让QProcess无限期地等待：
if (!s3.waitForFinished(-1)){
/// ...
}
注意：
来自waitForFinished()的文档：
警告：从主（GUI）线程调用此函数可能会导致用户界面冻结。