SERVER-41581 index_builds_ignore_prepare_conflicts.js should not start a transaction until the index build releases its exclusive lock

(cherry picked from commit e48c36a61634718f548f29aa0e1e3787fc1a979b)

1 files changed, 9 insertions, 4 deletions

diff --git a/jstests/noPassthrough/index_builds_ignore_prepare_conflicts.js b/jstests/noPassthrough/index_builds_ignore_prepare_conflicts.js
index 4973d4296d7..e46177d35b0 100644
--- a/jstests/noPassthrough/index_builds_ignore_prepare_conflicts.js
+++ b/jstests/noPassthrough/index_builds_ignore_prepare_conflicts.js
@@ -28,11 +28,11 @@
     const primary = replSetTest.getPrimary();
     const primaryDB = primary.getDB('test');
 
-    const docsToInsert = 10;
+    let numDocs = 10;
     let setUp = function(coll) {
         coll.drop();
         let bulk = coll.initializeUnorderedBulkOp();
-        for (let i = 0; i < docsToInsert; i++) {
+        for (let i = 0; i < numDocs; i++) {
             bulk.insert({i: i});
         }
         assert.commandWorked(bulk.execute());
@@ -54,6 +54,11 @@
         const awaitBuild = IndexBuildTest.startIndexBuild(primary, coll.getFullName(), {i: 1});
         const opId = IndexBuildTest.waitForIndexBuildToStart(testDB, collName, "i_1");
 
+        // This insert will block until the index build pauses and releases its exclusive lock.
+        // This guarantees that the subsequent transaction can immediately acquire a lock and not
+        // fail with a LockTimeout error.
+        assert.commandWorked(coll.insert({i: numDocs++}));
+
         // Start a session and introduce a document that is in a prepared state, but should be
         // ignored by the index build, at least until the transaction commits.
         const session = primaryDB.getMongo().startSession();
@@ -95,8 +100,8 @@
         awaitBuild();
         IndexBuildTest.waitForIndexBuildToStop(testDB, collName, "i_1");
 
-        assert.eq(docsToInsert, coll.count());
-        assert.eq(docsToInsert, coll.find().itcount());
+        assert.eq(numDocs, coll.count());
+        assert.eq(numDocs, coll.find().itcount());
     };
 
     runTest(replSetTest.getPrimary());