add dask_awkward support to fastjet

[lgray]

Fixes #188

Bindings appear to be pretty straightforward at the end of the day.

The trick we use to make delayed operations work is to construct a new ClusterSequence for each concrete array being processed.

Within DaskAwkwardClusterSequence we dispatch the function to be called and the JetDefinition.

There are a large number of functions to convert, but the majority of them seem pretty straightforward.

[lgray]

@chrispap95 OK - sorry for the noise here while I beat it into shape. This is all ready for completion now. Let me know if you have any questions!

There are perhaps a few places where it's not a trivial map_partitions but I haven't thought about it too hard.

[lgray]

We probably also need to turn on the thread safety options for fastjet now, since dask's default scheduler is threaded.

[lgray]

@chrispap95 ok - finished this up. It would be super useful to try this out with some user analysis and derive some tests before we merge it.

[lgray]

@andrzejnovak FYI

[chrispap95]

@lgray I can run the SUEP workflow on it. It is using only inclusive_jets and constituents though. Let me try to set up the environment and I will reply back.

[lgray]

@chrispap95 cool - dask-based NanoEvents in the awkward2_dev branch of coffea should work for PFNano so you may just be able to start from that.

[lgray]

@jmduarte I know you guys are using some of the lund plane functions and stuff - if you have some time could you give this new software stack a try?

[lgray]

There are some bugs in this that need fixing:

• it won't touch data correctly
• it's presently not handling the cases where the function has additional array arguments

[lgray]

OK - this is going to need some work now that I've got some tests running on a file.

Update: I have a janky fix that seems to work on files well.

@chrispap95 can you make a 2 event sample of that PFNano file you pointed me to so that I can make proper tests?
There's a lot of gotcha's in dask_awkward related to when you finally start reading from a file (and doing so efficiently).

[lgray]

@jpivarski Do you think this is reasonably robust enough? I checked in the code that deeper within all that is ever asked for is E/px/py/pz, but it all looks sorta sketchy IMO.

[lgray]

uuughhh