LHC@home

there is a Theory task running for more than a day now, and when looking up the VM console-F2 it says in every line: "inconsist mother/daughter information in Phytia8 event".
directly under each of these lines it says: "i = 19 mother = 17", or, further down: "i = 29 mother = 27" and so on.
There is no indication of events processed, as usually seen in console-F2.
Is the task broken and should I abort it?

Last year Peter Skands posted a comment regarding this:
https://lhcathome.cern.ch/lhcathome/forum_thread.php?id=5414&postid=42371

Last year Peter Skands posted a comment regarding this:
https://lhcathome.cern.ch/lhcathome/forum_thread.php?id=5414&postid=42371

haha

The problem arises because we introduced a new "bremsstrahlung shower" model into Pythia 8.301, called Vincia

"bremsstrahlung shower" sounds funny :-)
And yes, the task in question is Pythia 8.301.
So I guess I let it run until it finishes.

Thanks, computezrmle, for the hint :-)

I am kind of unsure by now whether this task is working the way it's supposed to.
It has been running for almost 4 days, which is unusual, but not impossible (very rarely, I've had tasks running up to 4 or even 5 days). Monitoring the Windows task manager shows me that the CPU is working for this task. Also console F3 shows a CPU utilisation of 98.6%. So the task is not dead, but could it be that it runs in some kind of never ending loop?
I am afraid I have no way to find out, have I?

When you check its running log does it still show *number of* - events have been generated ?

(example)
Pythia::next(): 7000 events have been generated
7000 events processed
dumping histograms...
7100 events processed
7200 events processed
7300 events processed
7400 events processed
7500 events processed
7600 events processed

and continue

When you check its running log does it still show *number of* - events have been generated ?

(example)
Pythia::next(): 7000 events have been generated
7000 events processed
dumping histograms...
7100 events processed

no, this is exactly the problem here, as I wrote in my inital posting:

There is no indication of events processed, as usually seen in console-F2.

If it doesn't start running *events* after 2 or 3 hours abort it.
That is always obvious if it has not done anything by then.

If it doesn't start running *events* after 2 or 3 hours abort it.
That is always obvious if it has not done anything by then.

the question though is: since it's using 1 CPU core - what is it doing if not processing events?

the task has been running for more than 5 days.
If it doesn't finish before this evening, I will kill it. I suspect it's a waste of time and CPU power :-(

I have received plenty of these tasks lately. How come, all of a sudden?

Atlas have also problems, see Atlas message folder.

Hi,

Generator updates and bug fixes are not always as fast as one might like, but I wanted to at least show that this one did get addressed, and thank those that wrote to us about the error messages they were seeing about inconsistent mother/daughter pointers, here from the program's update notes at pythia.org :

8.306: 28 June 2021
- Fixed issue for HepMC output from Vincia, which would previously issue warnings about inconsistent mother/daughter relationships, caused by Vincia's antenna-style bookkeeping by which emitted partons have two mothers instead of one. For status codes 43, 51, and 53, the HepMC interface now ignores the second parent, always using just the first one to define the vertex structure. Minor modifications to Vincia's QCD shower to ensure that the first mother is the one that changed colour and hence would be identified with the "radiator" in a collinear context. Analogous modifications in the QED module so the most collinear parent is the first mother.

Again, thanks as always for reporting issues that you see in the runs, and apologies if we are sometimes (very) slow to react to them; we are not a big group of people but have to cover a lot of ground.

All the best,
Peter Skands, on behalf of the Pythia team.