SERVER-24693 Test that the "group" command yields using explain().

(cherry picked from commit 5042151e09a828880658dd6f3cadee0e0eff2ec1)

2 files changed, 32 insertions, 47 deletions

diff --git a/jstests/core/group7.js b/jstests/core/group7.js
deleted file mode 100644
index 6d6ef03e99d..00000000000
--- a/jstests/core/group7.js
+++ /dev/null
@@ -1,47 +0,0 @@
-// Test yielding group command SERVER-1395
-
-t = db.jstests_group7;
-t.drop();
-
-function checkForYield(docs, updates) {
-    t.drop();
-    a = 0;
-    for (var i = 0; i < docs; ++i) {
-        t.save({a: a});
-    }
-
-    // Iteratively update all a values atomically.
-    p = startParallelShell(
-        'for( a = 0; a < ' + updates + '; ++a ) {' +
-        'db.jstests_group7.update({ $atomic: true }, { $set: { a: a }}, false, true);' +
-        '}');
-
-    for (var i = 0; i < updates; ++i) {
-        print("running group " + i + " of " + updates);
-        ret = t.group({key: {a: 1}, reduce: function() {}, initial: {}});
-        // Check if group sees more than one a value, indicating that it yielded.
-        if (ret.length > 1) {
-            p();
-            return true;
-        }
-        printjson(ret);
-    }
-
-    p();
-    return false;
-}
-
-var yielded = false;
-var docs = 1500;
-var updates = 50;
-for (var j = 1; j <= 6; ++j) {
-    print("Iteration " + j + " docs = " + docs + " updates = " + updates);
-    if (checkForYield(docs, updates)) {
-        yielded = true;
-        break;
-    }
-    // Increase docs and updates to encourage yielding.
-    docs *= 2;
-    updates *= 2;
-}
-assert(yielded);
diff --git a/jstests/noPassthrough/yield_group.js b/jstests/noPassthrough/yield_group.js
new file mode 100644
index 00000000000..4eb40623e19
--- /dev/null
+++ b/jstests/noPassthrough/yield_group.js
@@ -0,0 +1,32 @@
+/**
+ * Test that the "group" command yields periodically (SERVER-1395).
+ */
+(function() {
+    'use strict';
+
+    const nDocsToInsert = 300;
+    const worksPerYield = 50;
+
+    // Start a mongod that will yield every 50 work cycles.
+    var conn =
+        MongoRunner.runMongod({setParameter: `internalQueryExecYieldIterations=${worksPerYield}`});
+    assert.neq(null, conn, 'mongod was unable to start up');
+
+    var coll = conn.getDB('test').yield_group;
+
+    var bulk = coll.initializeUnorderedBulkOp();
+    for (var i = 0; i < nDocsToInsert; ++i) {
+        bulk.insert({_id: i});
+    }
+
+    var res = bulk.execute();
+    assert.writeOK(res);
+    assert.eq(nDocsToInsert, res.nInserted, tojson(res));
+
+    // A "group" command performing a collection scan should yield approximately
+    // nDocsToInsert / worksPerYield times.
+    var explain =
+        coll.explain('executionStats').group({key: {_id: 1}, reduce: function() {}, initial: {}});
+    var numYields = explain.executionStats.executionStages.saveState;
+    assert.gt(numYields, (nDocsToInsert / worksPerYield) - 2, tojson(explain));
+})();