Bug #20223: Excessive memory usage with huge containers - Arvados

We were fixated on update_priority but it looks like the thing that we were missing was that handle_completed can also load full container + container request records.

In the end the solution seems to be to simply optimize the queries for memory usage. I removed the use of includes and replaced it with either loading records one at a time or using pluck to grab the one field that we actually cared about (avoiding most of the ActiveRecord machinery entirely).

Even with all of that it looks like this operation still took 43 seconds to complete, but the good news is that I didn't see massive bloat in the ruby memory footprint.

Also, when all registered workflows are refreshed so that the workflow record is the wrapper workflow only, this should be much quicker, as the main overhead here is deserializing the workflow JSON content kept in the "mounts" field.

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Updated by Peter Amstutz about 1 year ago

Assigned To set to Peter Amstutz

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Updated by Lucas Di Pentima about 1 year ago

Changes LGTM.

I think I found another case where using .pluck() could be beneficial:

model/container_request.rb:L355 -- The old_container var will only be used to get the log field.

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Updated by Peter Amstutz about 1 year ago

Subject changed from Excessive time updating container state for parent container of workflow process tree to Excessive memory usage with huge containers

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Updated by Peter Amstutz about 1 year ago

I following up on this, it looks like trash_sweep and used_by are also problems.

developer-run-tests: #3546

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Updated by Peter Amstutz about 1 year ago

20223-trash-sweep @ effb6e13d6a4d024243138cacfeb582efba5e24a

developer-run-tests: #3547

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Updated by Lucas Di Pentima about 1 year ago

I think we can use pluck(:uuid) on collections_controller instead of in_batches() saving a lot of memory in the process.
All the in_batches(of: 15) calls makes me want to have a config knob that we can tune. Not sure if this would be a blocker for this to get merged, though.

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#10

Updated by Peter Amstutz about 1 year ago

20223-trash-sweep @ af90b8e123e227fe2c35902e3a80f49b15e6d067

Make used_by use pluck (and select in one case) instead of loading in batches, which should be way faster and more efficient.

developer-run-tests: #3549

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#11

Updated by Lucas Di Pentima about 1 year ago

I think we can even use pluck() in the multi-column case. I read that pluck() supported only 1 arg on rails 3 but since rails 4 it can support multiple args. https://apidock.com/rails/v5.2.3/ActiveRecord/Calculations/pluck

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#12