posting to an invalid URL using QNetworkAccessManager

[sattu]

Hi Everyone, I have a simple requirement on my Arm-Linux embedded platform wherein I need to post to a URL and wait for the reply. I achieve that using the following code-

void MyApp::MyApp()
{
m_networkManager = new QNetworkAccessManager(this);   // Instance variable
connect(m_networkManager, SIGNAL(finished(QNetworkReply*)),
this, SLOT(onRequestCompleted(QNetworkReply *)));
}
 
void MyApp::getData() 
{
QByteArray dataToBePosted;
QNetworkRequest request;
request.setUrl(QUrl("http://www.domain.foo"));
m_networkManager->post(request,dataToBePosted);
}
 
void MyApp::onRequestCompleted(QNetworkReply *reply) 
{
QByteArray data = reply->readAll();
reply->deleteLater();
}

void MyApp::MyApp()
{
m_networkManager = new QNetworkAccessManager(this);   // Instance variable
connect(m_networkManager, SIGNAL(finished(QNetworkReply*)),
this, SLOT(onRequestCompleted(QNetworkReply *)));
}

void MyApp::getData() 
{
QByteArray dataToBePosted;
QNetworkRequest request;
request.setUrl(QUrl("http://www.domain.foo"));
m_networkManager->post(request,dataToBePosted);
}

void MyApp::onRequestCompleted(QNetworkReply *reply) 
{
QByteArray data = reply->readAll();
reply->deleteLater();
}

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I have 2 doubts regarding usage of QNetworkAccessManager class-
1) What I observed is that if I post to a valid URL I immediately get a response, but if the URL is invalid then it takes some time for the reply to come (sometimes like 40 secs).
Moreover, if the URL is invalid then I observe an increase in memory usage in my application after the following line-

m_networkManager->post(request,dataToBePosted);

m_networkManager->post(request,dataToBePosted);

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I know this sounds very strange but this is what is happening. If the URL exists then everything is fine, but by mistake if I post to an invalid URL then my memory usage immediately shoots up

2) In Qt Documentation it is mentioned that

One QNetworkAccessManager should be enough for the whole Qt application.

Suppose I use 2 QNetworkAccessManager objects in my application, will that create any issue?

I would be really glad if someone would clarify my doubts.