remove canDeleteEarly feature of the framework

[Dr15Jones]

A long time ago we added a feature that let one say an Event data product could be deleted before the end of processing of the Event. No configuration outside of the framework unit tests make use of this feature.
This feature is dangerous since it requires exact knowledge of each module which may use the data product so the product is not deleted before those modules are run. For modules just getting the container directly the consumes call would be able to verify this. However, this fails if the container is associated with a Ref like instance. In that case we have no way to find such Refs nor know what modules might use them. When run with multiple threads such a Ref could be dereferenced at the exact same time the framework decides to delete the object.

[cmsbuild]

A new Issue was created by @Dr15Jones (Chris Jones).

@davidlange6, @smuzaffar, @Degano, @davidlt, @Dr15Jones can you please review it and eventually sign/assign? Thanks.

Following commands in first line of a comment are recognized

• +1|approve[d]|sign[ed]: L1/L2's to approve it
• -1|reject[ed]: L1/L2's to reject it
• assign <category>[,<category>[,...]]: L1/L2's to request signatures from other categories
• unassign <category>[,<category>[,...]]: L1/L2's to remove signatures from other categories
• hold: L1/all L2's/release manager to mark it as on hold
• unhold: L1/user who put this PR on hold
• merge: L1/release managers to merge this request

[Dr15Jones]

assign core

[cmsbuild]

New categories assigned: core

@Dr15Jones,@smuzaffar you have been requested to review this Pull request/Issue and eventually sign? Thanks

[slava77]

In HI processing (likely also in HL-LHC pileup environment) the total memory used often has a large fraction (about a half, maybe) consumed by transient products. If we could use the canDeleteEarly feature there in a safe way, we could save on some needed resources.

[smuzaffar]

@Dr15Jones , do we still want to remove this feature? Looks like it is now used in many places outside FW ( https://github.com/cms-sw/cmssw/search?q=canDeleteEarly&type=code )

[Dr15Jones]

@makortel

[makortel]

I think this issue can be closed in favor of #16481 .

[smuzaffar]

closing it in favor of #16481