SERVER-44626: Add new setParameter loadRoutingTableOnStartup

6 files changed, 36 insertions, 8 deletions

diff --git a/jstests/sharding/mongos_precache_routing_info.js b/jstests/sharding/mongos_precache_routing_info.js
index 2b4266a6d63..786d56149db 100644
--- a/jstests/sharding/mongos_precache_routing_info.js
+++ b/jstests/sharding/mongos_precache_routing_info.js
@@ -33,5 +33,16 @@ db = s.getDB("test");
 ss = db.serverStatus();
 assert.eq(1, ss.shardingStatistics.catalogCache.countFullRefreshesStarted);
 
+// does not pre cache when set parameter is disabled
+s.restartMongos(0, {
+    restart: true,
+    setParameter: {loadRoutingTableOnStartup: false},
+});
+db = s.getDB("test");
+
+// check for # refreshes started
+ss = db.serverStatus();
+assert.eq(0, ss.shardingStatistics.catalogCache.countFullRefreshesStarted);
+
 s.stop();
 })();
diff --git a/src/mongo/s/SConscript b/src/mongo/s/SConscript
index 1d4cc94c795..20cf7b4a6fd 100644
--- a/src/mongo/s/SConscript
+++ b/src/mongo/s/SConscript
@@ -105,7 +105,7 @@ env.Library(
     source=[
         'sharding_initialization.cpp',
         'sharding_task_executor_pool_controller.cpp',
-        'pre_warm_connection_pool_impl.cpp',
+        'warmup_server_parameters.cpp',
         env.Idlc('sharding_task_executor_pool.idl')[0],
         'client/sharding_connection_hook.cpp',
         'client/sharding_network_connection_hook.cpp',
diff --git a/src/mongo/s/mongos_options.idl b/src/mongo/s/mongos_options.idl
index 5c8033a24b0..a9d04e8d39e 100644
--- a/src/mongo/s/mongos_options.idl
+++ b/src/mongo/s/mongos_options.idl
@@ -31,12 +31,19 @@ global:
   cpp_namespace: "mongo"
   cpp_includes:
     - "mongo/s/mongos_options.h"
-    - "mongo/s/pre_warm_connection_pool_impl.h"
+    - "mongo/s/warmup_server_parameters.h"
   configs:
     section: "Sharding options"
     source: [ yaml, cli, ini ]
 
 server_parameters: 
+  loadRoutingTableOnStartup:
+    description: <-
+        Enables precaching of the mongos routing table on startup.
+    set_at: [ startup ]
+    cpp_varname: "gLoadRoutingTableOnStartup"
+    default: true
+
   warmMinConnectionsInShardingTaskExecutorPoolOnStartup:
     description: <-
         Enables prewarming of the connection pool.
diff --git a/src/mongo/s/sharding_initialization.cpp b/src/mongo/s/sharding_initialization.cpp
index f3598d797f3..733c0bcb3df 100644
--- a/src/mongo/s/sharding_initialization.cpp
+++ b/src/mongo/s/sharding_initialization.cpp
@@ -66,11 +66,11 @@
 #include "mongo/s/client/sharding_network_connection_hook.h"
 #include "mongo/s/cluster_identity_loader.h"
 #include "mongo/s/grid.h"
-#include "mongo/s/pre_warm_connection_pool_impl.h"
 #include "mongo/s/query/cluster_cursor_manager.h"
 #include "mongo/s/sharding_task_executor.h"
 #include "mongo/s/sharding_task_executor_pool_controller.h"
 #include "mongo/s/sharding_task_executor_pool_gen.h"
+#include "mongo/s/warmup_server_parameters.h"
 #include "mongo/stdx/thread.h"
 #include "mongo/util/concurrency/thread_pool.h"
 #include "mongo/util/exit.h"
@@ -263,9 +263,14 @@ Status waitForShardRegistryReload(OperationContext* opCtx) {
 }
 
 Status preCacheMongosRoutingInfo(OperationContext* opCtx) {
+    if (!gLoadRoutingTableOnStartup) {
+        return Status::OK();
+    }
+
     if (serverGlobalParams.clusterRole == ClusterRole::ConfigServer) {
         return Status::OK();
     }
+
     auto grid = Grid::get(opCtx);
 
     auto shardingCatalogClient = grid->catalogClient();
@@ -298,9 +303,6 @@ Status preWarmConnectionPool(OperationContext* opCtx) {
         return Status::OK();
     }
 
-    // Should not be called by mongod
-    invariant(serverGlobalParams.clusterRole != ClusterRole::ShardServer);
-
     std::vector<HostAndPort> allHosts;
     auto const grid = Grid::get(opCtx);
     auto allShardsStatus =
diff --git a/src/mongo/s/pre_warm_connection_pool_impl.cpp b/src/mongo/s/warmup_server_parameters.cpp
index cb082983ce1..3809bf64844 100644
--- a/src/mongo/s/pre_warm_connection_pool_impl.cpp
+++ b/src/mongo/s/warmup_server_parameters.cpp
@@ -27,12 +27,13 @@
  *    it in the license file.
  */
 
-#include "mongo/s/pre_warm_connection_pool_impl.h"
+#include "mongo/s/warmup_server_parameters.h"
 
 
 namespace mongo {
 
+bool gLoadRoutingTableOnStartup = true;
 bool gWarmMinConnectionsInShardingTaskExecutorPoolOnStartup = true;
 int gWarmMinConnectionsInShardingTaskExecutorPoolOnStartupWaitMS = 2000;
 
-}  // namespace mongo
\ No newline at end of file
+}  // namespace mongo
diff --git a/src/mongo/s/pre_warm_connection_pool_impl.h b/src/mongo/s/warmup_server_parameters.h
index f5b4a5dfbe0..9d1b616b322 100644
--- a/src/mongo/s/pre_warm_connection_pool_impl.h
+++ b/src/mongo/s/warmup_server_parameters.h
@@ -31,6 +31,13 @@
 
 namespace mongo {
 /**
+ * Set parameter used to control whether or not the mongos attempts to precache the routing table on
+ * startup.
+ */
+
+extern bool gLoadRoutingTableOnStartup;
+
+/**
  * Set parameters used to control whether or not the mongos attempts to warm up the connection
  * pool on start up and for how long it should try.
  */