Feature #13275

Disabling fast cloning on data products with updated checksum

Added by Gianluca Petrillo over 4 years ago. Updated over 4 years ago.

Paul Russo
Target version:
Start date:
Due date:
% Done:


Estimated time:
24.00 h
Spent time:
SSI Package:


RootOutput's fastCloning fails when the running data product definition is changed respect to the one stored in the input ROOT file.
Failure mode is currently via exception.
Disabling fastCloning is possible from job configuration on a per-job basis, and it affects all the data products in the same way.

LArSoft would like the possibility to disable fast cloning on a per-data product basis, and even better it would be if art could detect when that is needed for each product.
This would make run-time schema evolution completely automatic for the experiments.


#1 Updated by Christopher Backhouse over 4 years ago

In practice NOvA's fcls are all littered with fastCloning: false, so we never get the benefits of fast cloning even in the cases where it could have been used, and having to add those lines is one of the most common gotchas for new users.

So, I'm definitely in favour of (the automatic part of) this request.

#2 Updated by Kyle Knoepfel over 4 years ago

  • Status changed from New to Assigned
  • Assignee set to Paul Russo
  • Estimated time set to 24.00 h

#3 Updated by Paul Russo over 4 years ago

It should be noted that ROOT 6 does not currently support cloning individual branches of a tree, cloning is a whole-tree operation.

However it is still possible for art to issue an informational message when it is not possible to clone a branch and continue on copying branches event-by-event in the normal manner without throwing an exception and ending the job.

#4 Updated by Paul Russo over 4 years ago

Feature added with commit eb7f8833682e8ea7719421bec5a887f71d858ed4. If fast cloning fails then instead of failing the job art will continue using normal event processing instead.

#5 Updated by Paul Russo over 4 years ago

  • Status changed from Assigned to Resolved
  • % Done changed from 0 to 100

#6 Updated by Kyle Knoepfel over 4 years ago

  • Status changed from Resolved to Closed
  • Target version set to 2.03.00

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