Tools want to be as little disrupting to the environment they run in as possible, because they might be run in a production environment, next to a running scylladb production server. As such, the usual behavior of seastar applications w.r.t. memory is an anti-pattern for tools: they don't want to reserve most of the system memory, in fact they don't want to reserve any amount, instead consuming as much as needed on-demand.
To achieve this, tools want to use the standard allocator. To achieve this they need a seastar option to to instruct seastar to *not* configure and use the seastar allocator and they need LSA to cooperate with the standard allocator.
The former is provided by https://github.com/scylladb/seastar/pull/1211.
The latter is solved by introducing the concept of a `segment_store_backend`, which abstracts away how the memory arena for segments is acquired and managed. We then refactor the existing segment store so that the seastar allocator specific parts are moved to an implementation of this backend concept, then we introduce another backend implementation appropriate to the standard allocator.
Finally, tools configure seastar with the newly introduced option to use the standard allocator and similarly configure LSA to use the standard allocator appropriate backend.
Refs: https://github.com/scylladb/scylladb/issues/9882
This is the last major code piece in scylla for making tools production ready.
Closes#11510
* github.com:scylladb/scylladb:
test/boost: add alternative variant of logalloc test
tools: use standard allocator
utils/logalloc: add use_standard_allocator_segment_pool_backend()
utils/logalloc: introduce segment store backend for standard allocator
utils/logalloc: rebase release segment-store on segment-store-backend
utils/logalloc: introduce segment_store_backend
utils/logalloc: push segment alloc/dealloc to segment_store
test/boost/logalloc_test: make test_compaction_with_multiple_regions exception-safe
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