use fabric to read/write _replicator docs#6031
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nickva
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Jun 10, 2026
| ioq:maybe_set_io_priority({system, DbName}), | ||
| defer_call(fun() -> | ||
| try | ||
| fabric:update_doc(DbName, Doc, [?CTX]) |
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With serialize_worker_startup=false currently we're using at cloudant, wouldn't this make the conflict generation worse?
nickva
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Jun 10, 2026
| Ret; | ||
| {'DOWN', Ref, process, Pid, {exit_throw, Reason}} -> | ||
| throw(Reason); | ||
| {'DOWN', Ref, process_, Pid, {exit_error, Reason}} -> |
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typo :process_ will deadlock on exits
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| save_rep_doc(<<"shards/", _/binary>> = ShardDbName, Doc) -> | ||
| DbName = mem3:dbname(ShardDbName), | ||
| ioq:maybe_set_io_priority({system, DbName}), |
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This doesn't do anything, same reason as above
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| open_rep_doc(<<"shards/", _/binary>> = ShardDbName, DocId) -> | ||
| DbName = mem3:dbname(ShardDbName), | ||
| ioq:maybe_set_io_priority({system, DbName}), |
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ioq setting here will fail. It's a pdict setting and since defer spawns a process it won't be applied
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closes #6029
Overview
serialize_worker_startup=true fixes the "spurious conflict" update case in most circumstances. A prior attempt to address that problem in the replicator now conflicts with that work. The replicator can update replicator docs whenever the state changes. For jobs that crash quickly, stored conflicts could be generated. We changed the replicator to only write to the local copy on the "owner" node, to avoid this. That is fundamentally the same trick that serialize_worker_startup=true does. However these two mechanisms are not coordinated and can easily choose different primary nodes.
This PR returns couch replicator to use fabric:open_doc and fabric:update_doc to align its changes with serialize_worker_startup=true behaviour.
Testing recommendations
covered by existing tests
Related Issues or Pull Requests
#6029
Checklist
rel/overlay/etc/default.inisrc/docsfolder