Re: Qt thread seems blocked in ipython after gROOT.ProcessLine

Hi Valeri,

> Where is your Qt thread come from?

That was my (probably wrong) guess that there was a thread running watching for necessary GUI updates.

> Anyway, if you want the Qt thread working you should use PyRoot with
> QtRoot plugin. The latter is to provide you the Qt eventloop you (your
> application;-) likely need to manage the QThread messages properly.

I do not have QtRoot available and don't have enough control over my installation.

> It is hard to be more concrete. One needs to see your code. Sorry, I
> did not understand why you spoke about the QThread yet.

I reduced the problematic code to the snippet I provided. Here it is again:

> > #!/bin/env ipython
> > import ROOT as r
> >
> > # uncommenting this blocks TCanvas updates
> > #r.gROOT.ProcessLine('.x ~/.root_logon.C')
> >
> > When I execute this file and interactively enter
> >
> > h = r.TH1D('h', '', 100, -10, 10)
> > h.Draw()
> > h.FillRandom('gaus', 1000)
> > h.Draw()
> >
> > ...

Prompted by your suggestion to "create my application the ROOT way" I just for fun replaced

    r.gROOT.ProcessLine('.x ~/.root_logon.C')

with

    app = r.TRint('app')

and ended up with the same problem of the canvas not updating automatically after modification anymore.

To make sure I'd screw up as little as possible I emptied my .root_logon.C file so that it now looks like

    {
    }

My guess is that there is some automatic magic going on behind the scenes when I call gROOT.ProcessLine (like initialization of static objects) which messes up the canvas updates in my case. My question was how to work around this.

Thank you for your help,

Benjamin