1 files changed, 54 insertions, 0 deletions
diff --git a/jstests/sharding/secondary_cache_reload_no_hang.js b/jstests/sharding/secondary_cache_reload_no_hang.js
new file mode 100644
index 00000000000..e6b54e04ba9
--- /dev/null
+++ b/jstests/sharding/secondary_cache_reload_no_hang.js
@@ -0,0 +1,54 @@
+/**
+ * TODO: SERVER-44105 maybe remove this test.
+ * This test is a simplified version that tries to simulate the condition described in
+ * SERVER-42737. It is very hard to replicate the exact condition because of:
+ *
+ * https://github.com/mongodb/mongo/blob/r4.3.0/src/mongo/db/s/shard_server_catalog_cache_loader.cpp#L293
+ *
+ * This means that secondary should be replicating a newer refresh after that line
+ * above and hit the condition described in the ticket to hit the bug.
+ */
+(function() {
+let rsOptions = {nodes: 2};
+let st = new ShardingTest({shards: {rs0: rsOptions, rs1: rsOptions}});
+
+assert.commandWorked(st.s.adminCommand({enableSharding: 'test'}));
+st.ensurePrimaryShard('test', st.shard0.shardName);
+assert.commandWorked(st.s.adminCommand({shardCollection: 'test.user', key: {x: 1}}));
+assert.commandWorked(st.s.adminCommand({split: 'test.user', middle: {x: 0}}));
+
+let coll = st.s.getDB('test').user;
+
+assert.commandWorked(coll.insert({x: -1}));
+assert.commandWorked(coll.insert({x: 1}));
+
+assert.commandWorked(
+    st.s.adminCommand({moveChunk: 'test.user', find: {x: 0}, to: st.shard1.shardName}));
+
+// Manually set refreshing flag to true so secondary cache refresh will block.
+
+st.rs0.getPrimary().getDB('config').cache.collections.update(
+    {_id: 'test.user', fake: {'$exists': false}}, {$set: {refreshing: true}});
+
+// Add a delay (sleep) to make sure that secondary will have the {refreshing: true}
+// in the lastApplied snapshot and is blocked waiting for refreshing to become false
+// before sending update to primary.
+
+let joinUpdate = startParallelShell(
+    'sleep(1000);' +
+        'db.getSiblingDB("config").cache.collections.update(' +
+        '{_id: "test.user", fake: {"$exists": false}},' +
+        '{$set: {refreshing: false, lastRefreshedCollectionVersion: Timestamp(5, 0)}});',
+    st.rs0.getPrimary().port);
+
+// This secondary read should not cause a hang.
+st.s.setReadPref('secondary');
+let res = assert.commandWorked(coll.getDB('test').runReadCommand(
+    {find: 'user', filter: {dummy: {'$exists': false}}, readConcern: {level: 'local'}}));
+
+assert.eq(2, res.cursor.firstBatch.length, tojson(res));
+
+joinUpdate();
+
+st.stop();
+})();