SERVER-41340 Enable Flow Control by default

5 files changed, 15 insertions, 14 deletions

diff --git a/buildscripts/resmokelib/config.py b/buildscripts/resmokelib/config.py
index bc245b2e682..4004823845e 100644
--- a/buildscripts/resmokelib/config.py
+++ b/buildscripts/resmokelib/config.py
@@ -373,7 +373,8 @@ STAGGER_JOBS = None
 # If set to true, it enables read concern majority. Else, read concern majority is disabled.
 MAJORITY_READ_CONCERN = None
 
-# If set to true, it enables flow control. Else, flow control is disabled.
+# If set to "on", it enables flow control. If set to "off", it disables flow control. If left as
+# None, the server's default will determine whether flow control is enabled.
 FLOW_CONTROL = None
 
 # If set, then all mongod's started by resmoke.py and by the mongo shell will use the specified
diff --git a/buildscripts/resmokelib/core/programs.py b/buildscripts/resmokelib/core/programs.py
index 881c096d173..ba12be817fe 100644
--- a/buildscripts/resmokelib/core/programs.py
+++ b/buildscripts/resmokelib/core/programs.py
@@ -119,8 +119,8 @@ def mongod_program(  # pylint: disable=too-many-branches
     if "replSet" in kwargs and "waitForStepDownOnNonCommandShutdown" not in suite_set_parameters:
         suite_set_parameters["waitForStepDownOnNonCommandShutdown"] = False
 
-    if "enableFlowControl" not in suite_set_parameters:
-        suite_set_parameters["enableFlowControl"] = config.FLOW_CONTROL
+    if "enableFlowControl" not in suite_set_parameters and config.FLOW_CONTROL is not None:
+        suite_set_parameters["enableFlowControl"] = (config.FLOW_CONTROL == "on")
 
     _apply_set_parameters(args, suite_set_parameters)
 
@@ -276,7 +276,8 @@ def mongo_shell_program(  # pylint: disable=too-many-branches,too-many-locals,to
 
     # If the 'enableFlowControl' setParameter for mongod was not already specified, we set its value
     # to a default.
-    mongod_set_parameters.setdefault("enableFlowControl", config.FLOW_CONTROL)
+    if config.FLOW_CONTROL is not None:
+        mongod_set_parameters.setdefault("enableFlowControl", config.FLOW_CONTROL == "on")
 
     # If the 'logComponentVerbosity' setParameter for mongos was not already specified, we set its
     # value to a default.
@@ -389,7 +390,8 @@ def dbtest_program(logger, executable=None, suites=None, process_kwargs=None, **
     if config.STORAGE_ENGINE is not None:
         kwargs["storageEngine"] = config.STORAGE_ENGINE
 
-    kwargs["flowControl"] = config.FLOW_CONTROL
+    if config.FLOW_CONTROL is not None:
+        kwargs["flowControl"] = (config.FLOW_CONTROL == "on")
 
     return generic_program(logger, args, process_kwargs=process_kwargs, **kwargs)
 
diff --git a/buildscripts/resmokelib/parser.py b/buildscripts/resmokelib/parser.py
index 3d3bf63cb5b..ebb0ebd1a0b 100644
--- a/buildscripts/resmokelib/parser.py
+++ b/buildscripts/resmokelib/parser.py
@@ -250,8 +250,7 @@ def _make_parser():  # pylint: disable=too-many-statements
 
     parser.add_option("--flowControl", type="choice", action="store", dest="flow_control",
                       choices=("on",
-                               "off"), metavar="ON|OFF", help=("Enable or disable flow control."
-                                                               " Defaults to %default."))
+                               "off"), metavar="ON|OFF", help=("Enable or disable flow control."))
 
     parser.add_option("--storageEngine", dest="storage_engine", metavar="ENGINE",
                       help="The storage engine used by dbtests and jstests.")
@@ -382,8 +381,7 @@ def _make_parser():  # pylint: disable=too-many-statements
 
     parser.set_defaults(benchrun_device="Desktop", dry_run="off", find_suites=False,
                         list_suites=False, logger_file="console", shuffle="auto",
-                        stagger_jobs="off", suite_files="with_server", majority_read_concern="on",
-                        flow_control="on")
+                        stagger_jobs="off", suite_files="with_server", majority_read_concern="on")
     return parser
 
 
@@ -571,7 +569,7 @@ def _update_config_vars(values):  # pylint: disable=too-many-statements
     _config.EXCLUDE_WITH_ANY_TAGS.extend(
         utils.default_if_none(_tags_from_list(config.pop("exclude_with_any_tags")), []))
     _config.FAIL_FAST = not config.pop("continue_on_failure")
-    _config.FLOW_CONTROL = config.pop("flow_control") == "on"
+    _config.FLOW_CONTROL = config.pop("flow_control")
     _config.INCLUDE_WITH_ANY_TAGS = _tags_from_list(config.pop("include_with_any_tags"))
     _config.GENNY_EXECUTABLE = _expand_user(config.pop("genny_executable"))
     _config.JOBS = config.pop("jobs")
diff --git a/etc/system_perf.yml b/etc/system_perf.yml
index ca7c1e45caa..86e02368916 100644
--- a/etc/system_perf.yml
+++ b/etc/system_perf.yml
@@ -1071,12 +1071,12 @@ buildvariants:
     - name: linkbench
     - name: big_update
 
-- name: linux-3-node-replSet-flowcontrol
-  display_name: Linux 3-Node ReplSet with Flow Control
+- name: linux-3-node-replSet-noflowcontrol
+  display_name: Linux 3-Node ReplSet (Flow Control off)
   batchtime: 1440  # 24 hours
   modules: *modules
   expansions:
-    setup: replica-flowcontrol
+    setup: replica-noflowcontrol
     cluster: replica
     platform: linux
     project_dir: *project_dir
diff --git a/src/mongo/db/storage/flow_control_parameters.idl b/src/mongo/db/storage/flow_control_parameters.idl
index 2dd83afba0a..57a8b47a585 100644
--- a/src/mongo/db/storage/flow_control_parameters.idl
+++ b/src/mongo/db/storage/flow_control_parameters.idl
@@ -34,7 +34,7 @@ server_parameters:
         set_at: [ startup, runtime ]
         cpp_vartype: 'AtomicWord<bool>'
         cpp_varname: 'gFlowControlEnabled'
-        default: false
+        default: true
     flowControlTargetLagSeconds:
         description: 'Target maximum majority committed lag with flow control enabled'
         set_at: [ startup, runtime ]