3.x: Disable fusion on the groups of Flowable.groupBy #6983
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davidmoten approved these changes May 13, 2020
Codecov Report
@@ Coverage Diff @@ ## 3.x #6983 +/- ## ============================================ - Coverage 99.61% 99.55% -0.06% Complexity 6669 6669 ============================================ Files 742 742 Lines 47270 47267 -3 Branches 6375 6374 -1 ============================================ - Hits 47086 47055 -31 - Misses 60 96 +36 + Partials 124 116 -8
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This PR disables the async fusion capability of the groups emitted by
Flowable.groupByas it appears to lead to hangs due to cancellation and/or lack of requests in certain async scenarios.By disabling fusion, the groups will manage the items they queue and cancellation will (hopefully) properly trigger replenishment requests for the unclaimed items.
This is more of a workaround than a comprehensible fix for the underlying issues. The main problem is that with
groupByand backpressure, each group itself and the items passing through them now count as resources and Reactive Streams can't cope well with items requiring their own lifecycle.Related: #6982