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Backwards Compatibility:
Fully Compatible
Operating System:
ALL
Backport Requested:

v4.4
Steps To Reproduce:
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Issue a hedged read

const st = new ShardingTest({shards: 2, rs: {nodes: 2}}); const dbName = "foo"; const collName = "bar"; const ns = dbName + "." + collName; const testDB = st.s.getDB(dbName); assert.commandWorked(testDB.runCommand({ query: { find: collName, filter: {$where: "sleep(100); return true;"}, $readPreference: {mode: "nearest"} } }));

and verify that the hedged read connection returns failed status
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Issue a hedged read const st = new ShardingTest({shards: 2, rs: {nodes: 2}}); const dbName = "foo" ; const collName = "bar" ; const ns = dbName + "." + collName; const testDB = st.s.getDB(dbName); assert .commandWorked(testDB.runCommand({ query: { find: collName, filter: {$where: "sleep(100); return true ;" }, $readPreference: {mode: "nearest" } } })); and verify that the hedged read connection returns failed status
Sprint:
Service Arch 2020-03-23, Service Arch 2020-04-06
Linked BF Score:
0

The issue is manifested when a hedge read finishes after the original read by marking the connection as failed
It happens because of the baton used for sending the RemoteCommandRequest is detached when the request returns.
The baton is owned by ARS which goes out of scope when the primary request finishes

depends on

SERVER-47139 Introduce GuaranteedExecutor class

is depended on by

SERVER-46512 Ensure that connections acquired for hedged reads can be reused

SERVER-46051 Change stream sys-perf regression due to SERVER-45691

related to

SERVER-46617 Improve NetworkInterfaceTL performance