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/**
* Confirms that a sharded $sample which employs the DSSampleFromRandomCursor optimization is
* capable of yielding.
*
* @tags: [assumes_read_concern_unchanged, do_not_wrap_aggregations_in_facets, requires_journaling,
* requires_sharding]
*/
(function() {
"use strict";
load("jstests/libs/fixture_helpers.js"); // For FixtureHelpers.
// Set up a 2-shard cluster. Configure 'internalQueryExecYieldIterations' on both shards such
// that operations will yield on each PlanExecuter iteration.
const st = new ShardingTest({
name: jsTestName(),
shards: 2,
rs: {nodes: 1, setParameter: {internalQueryExecYieldIterations: 1}}
});
const mongosDB = st.s.getDB(jsTestName());
const mongosColl = mongosDB.test;
// Shard the test collection, split it at {_id: 0}, and move the upper chunk to shard1.
st.shardColl(mongosColl, {_id: 1}, {_id: 0}, {_id: 0});
// Insert enough documents on each shard to induce the $sample random-cursor optimization.
for (let i = (-150); i < 150; ++i) {
assert.commandWorked(mongosColl.insert({_id: i}));
}
// Run the initial aggregate for the $sample stage.
const cmdRes = assert.commandWorked(mongosDB.runCommand({
aggregate: mongosColl.getName(),
pipeline: [{$sample: {size: 3}}],
comment: "$sample random",
cursor: {batchSize: 0}
}));
assert.eq(cmdRes.cursor.firstBatch.length, 0);
// Force each shard to hang on yield to allow for currentOp capture.
FixtureHelpers.runCommandOnEachPrimary({
db: mongosDB.getSiblingDB("admin"),
cmdObj: {
configureFailPoint: "setYieldAllLocksHang",
mode: "alwaysOn",
data: {namespace: mongosColl.getFullName()}
}
});
// Run $currentOp to confirm that the $sample getMore yields on both shards.
const awaitShell = startParallelShell(() => {
load("jstests/libs/fixture_helpers.js");
assert.soon(() => db.getSiblingDB("admin")
.aggregate([
{$currentOp: {}},
{
$match: {
"cursor.originatingCommand.comment": "$sample random",
planSummary: "QUEUED_DATA, MULTI_ITERATOR",
numYields: {$gt: 0}
}
}
])
.itcount() === 2);
// Release the failpoint and allow the getMores to complete.
FixtureHelpers.runCommandOnEachPrimary({
db: db.getSiblingDB("admin"),
cmdObj: {configureFailPoint: "setYieldAllLocksHang", mode: "off"}
});
}, mongosDB.getMongo().port);
// Retrieve the results for the $sample aggregation.
const sampleCursor = new DBCommandCursor(mongosDB, cmdRes);
assert.eq(sampleCursor.toArray().length, 3);
// Confirm that the parallel shell completes successfully, and tear down the cluster.
awaitShell();
st.stop();
})();
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