raft: add backpressure for CommittedEntries flow #60
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This commit introduces a mechanism for limiting the flow of CommittedEntries that raft pushes through the Ready handling loop. Signed-off-by: Pavel Kalinnikov <pavel@cockroachlabs.com>
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This commit introduces a mechanism for limiting the flow of
CommittedEntriesthat raft pushes through theReadyhandling loop.TODO: describe problem. In short, raft pushes work to be done via
Readyand expects it to be done, there is no backpressure mechanism. In CRDB, for instance, where there are many raft instances per node, many raft loops can push too much work simultaneously and cause out-of-memory situation.TODO: describe solution, and alternatives. There are more complicated alternatives, like making the in-flight limit dynamic, passing an int limit instead of bool, but seemingly the simplest possible bool does the job well.