Zhu Zhu created FLINK-14701: ------------------------------- Summary: Slot leaks if SharedSlotOversubscribedException happens Key: FLINK-14701 URL: https://issues.apache.org/jira/browse/FLINK-14701 Project: Flink Issue Type: Bug Components: Runtime / Coordination Affects Versions: 1.10.0, 1.9.2 Reporter: Zhu Zhu Fix For: 1.10.0, 1.9.2
If a {{SharedSlotOversubscribedException}} happens, the {{MultiTaskSlot}} will release some of its child {{SingleTaskSlot}}. The triggered releasing will trigger a re-allocation of the task slot right inside {{SingleTaskSlot#release(...)}}. So that a previous allocation in {{SloSharingManager#allTaskSlots}} will be replaced by the new allocation because they share the same {{slotRequestId}}. However, the {{SingleTaskSlot#release(...)}} will then invoke {{MultiTaskSlot#releaseChild}} to release the previous allocation with the {{slotRequestId}}, which will unexpectedly remove the new allocation from the {{SloSharingManager}}. In this way, slot leak happens because the pending slot request is not tracked by the {{SloSharingManager}} and cannot be released when its payload terminates. A test case {{testNoSlotLeakOnSharedSlotOversubscribedException}} which exhibits this issue can be found in this [commit|https://github.com/zhuzhurk/flink/commit/9024e2e9eb4bd17f371896d6dbc745bc9e585e14]. The slot leak blocks the TPC-DS queries on flink 1.10, see FLINK-14674. To solve it, I'd propose to strengthen the {{MultiTaskSlot#releaseChild}} to only remove its true child task slot from the {{SloSharingManager}}, i.e. add a check {{if (child == allTaskSlots.get(child.getSlotRequestId()))}} before invoking {{allTaskSlots.remove(child.getSlotRequestId())}}. -- This message was sent by Atlassian Jira (v8.3.4#803005)