QtConcurrent::run Access violation reading location

SGaist

Since it's a pointer:

@if (reply)@

Unless something is wrong, reply should either be NULL or pointing to a valid QNetworkReply (AFAIK, It shouldn't be NULL, but it's better to check to ensure that's not that that is causing you the access violation)

? Offline

I edit the code
@QString MainWindow::doRequest(QString url)
{
QString out;
QTimer timer;
QNetworkAccessManager* manager = new QNetworkAccessManager;
QEventLoop loop;
QObject::connect(&timer,SIGNAL(timeout()),&loop,SLOT(quit()));
QObject::connect(manager,SIGNAL(finished(QNetworkReply*)),&loop,SLOT(quit()));
QNetworkReply* reply = manager->get(QNetworkRequest(QUrl(url)));
timer.start(TIMEOUT);
loop.exec();
if(!timer.isActive())
{
reply->abort();
}
else
{
if(!reply) ::Beep(1000,1000);
if(reply->error() == QNetworkReply::NoError)
{
out = QString::QString( reply->readAll() );
}
reply->close();
}
reply->deleteLater();
manager->deleteLater();
return out;
}@

And i got error
!http://clip2net.com/clip/m0/1373183493-clip-9kb.png(1)!

So, i never heard beep

SGaist

I would check reply sooner, you might be calling abort on an invalid reply (though it would be strange)

? Offline

I edit
@loop.exec();
if(!reply)
{
::Beep(10000,10000);
exit(123456);
}@
But i got same violation error
Maybe I need to create exeptions?

SGaist

Are you sure everything you are accessing is valid (like links[i]) ?

? Offline

I think yes, i get errors in the middle of work process

? Offline

I runned it from cdb debugger. I see many errors, its showed at startup
@:0: предупреждение: Exception at 0x7c812aeb, code: 0x6ba: RPC server unavailable, flags=0x1 (execution cannot be continued) (first chance)

:0: предупреждение: Exception at 0x7c812aeb, code: 0x6ba: RPC server unavailable, flags=0x1 (execution cannot be continued) (first chance)

:0: предупреждение: Exception at 0x7c812aeb, code: 0x406d1388: Startup complete, flags=0x0 (first chance)

:0: предупреждение: Exception at 0x7c812aeb, code: 0x6ba: RPC server unavailable, flags=0x1 (execution cannot be continued) (first chance)

:0: предупреждение: Exception at 0x7c812aeb, code: 0x6a6: Invalid RPC server, flags=0x1 (execution cannot be continued) (first chance)@

So, on my pc RPC service is runned

SGaist

Then are you sure your server is running and that you can make as much connection that you are trying ?

? Offline

Oh, i haven't server, i have only this code.
And i don't click any buttons, i only run application and see errors

SGaist

Then I would :

First step: ensure the server is responding
Second step: try to access the server with one query
Third step: try with several queries in a row
Forth step: Try to parallelize your queries

That might include refactoring your code so that for example you'll use QtConcurrent::map to call your function with all the queries from a QList rather than accessing them yourself

? Offline

I have more than 100 servers, i can't do it ;(
But when i use 1 thread all works correctly. Sometimes some servers are disabled

SGaist

Then I would refactor the code so that it doesn't use a while loop. Create a QList of queries and either use map or mapped (depending on wether you return a value or not, I think you do return a value)

That would leave the entire parallelization to Qt and you'll only have to worry about retrieving the data.

? Offline

!http://clip2net.com/clip/m0/1373740625-clip-47kb.png(1)!
I launched it from debugger and i see it >_>
So many bugs, its increases on 5-10 every second

SGaist

Did you try starting with only one thread ? And then parallelizing with two and only then more ?

? Offline

Yes, i started in one thread. I found the bug in doRequest method.
I don't know, but he's somewhere in filing the request
But why? I do all correctly

SGaist

In that case, you can always use a request known to work for testing that part of your code while debugging the request build part

? Offline

I get critical exeption and warnings in
@loop.exec();@

And many warnings in
@QNetworkReply* reply = manager->get(QNetworkRequest(QUrl(url)));@

SGaist

What are the exceptions and warnings ?

? Offline

Those that are in the picture

SGaist

Did you do a test with a more conventional setup ? I mean have a simple application that creates one QNetworkAccessManager, do one request and get the answer in a slot ?

Seeing that each time you have a RPC server not available warning, that leads me to think that there is something wrong when communicating with the servers.

Like I said before, start small, validate that one query works in a standard setup. Then once that is good, do the same with the "blocking" event loop and then only start multi-threading