Add option to enable serial GC

common/settings.cc

@@ -45,6 +45,7 @@ std::string Settings::ToString() const {
   stream << "endless_trace_buffer: " << endless_trace_buffer << std::endl;
   stream << "enable_dart_profiling: " << enable_dart_profiling << std::endl;
   stream << "disable_dart_asserts: " << disable_dart_asserts << std::endl;
+  stream << "enable_serial_gc: " << enable_serial_gc << std::endl;
   stream << "enable_observatory: " << enable_observatory << std::endl;
   stream << "enable_observatory_publication: " << enable_observatory_publication
          << std::endl;

common/settings.h

@@ -140,6 +140,7 @@ struct Settings {
   bool endless_trace_buffer = false;
   bool enable_dart_profiling = false;
   bool disable_dart_asserts = false;
+  bool enable_serial_gc = false;
 
   // Whether embedder only allows secure connections.
   bool may_insecurely_connect_to_all_domains = true;

runtime/dart_vm.cc

@@ -59,6 +59,16 @@ static const char* kDartLanguageArgs[] = {
 
 static const char* kDartPrecompilationArgs[] = {"--precompilation"};
 
+static const char* kSerialGCArgs[] = {
+    // clang-format off
+    "--concurrent_mark=false",
+    "--concurrent_sweep=false",
+    "--compactor_tasks=1",
+    "--scavenger_tasks=0",
+    "--marker_tasks=0",
+    // clang-format on
+};
+
 FML_ALLOW_UNUSED_TYPE
 static const char* kDartWriteProtectCodeArgs[] = {
     "--no_write_protect_code",
@@ -358,6 +368,13 @@ DartVM::DartVM(std::shared_ptr<const DartVMData> vm_data,
     PushBackAll(&args, kDartAssertArgs, fml::size(kDartAssertArgs));
   }
 
+  // On low power devices with lesser number of cores, using concurrent
+  // marking or sweeping causes contention for the UI thread leading to
+  // Jank, this option can be used to turn off all concurrent GC activities.
+  if (settings_.enable_serial_gc) {
+    PushBackAll(&args, kSerialGCArgs, fml::size(kSerialGCArgs));
+  }
+
   if (settings_.start_paused) {
     PushBackAll(&args, kDartStartPausedArgs, fml::size(kDartStartPausedArgs));
   }

shell/common/switches.cc

@@ -300,6 +300,9 @@ Settings SettingsFromCommandLine(const fml::CommandLine& command_line) {
   settings.trace_startup =
       command_line.HasOption(FlagForSwitch(Switch::TraceStartup));
 
+  settings.enable_serial_gc =
+      command_line.HasOption(FlagForSwitch(Switch::EnableSerialGC));
+
 #if !FLUTTER_RELEASE
   settings.trace_skia = true;
 

shell/common/switches.h

@@ -193,6 +193,12 @@ DEF_SWITCH(DisableDartAsserts,
            "disabled. This flag may be specified if the user wishes to run "
            "with assertions disabled in the debug product mode (i.e. with JIT "
            "or DBC).")
+DEF_SWITCH(EnableSerialGC,
+           "enable-serial-gc",
+           "On low power devices with low core counts, running concurrent "
+           "GC tasks on threads can cause them to contend with the UI thread "
+           "which could potentially lead to jank. This option turns off all "
+           "concurrent GC activities")
 DEF_SWITCH(DisallowInsecureConnections,
            "disallow-insecure-connections",
            "By default, dart:io allows all socket connections. If this switch "

testing/dart/BUILD.gn

@@ -34,6 +34,7 @@ tests = [
   "platform_view_test.dart",
   "plugin_utilities_test.dart",
   "semantics_test.dart",
+  "serial_gc_test.dart",
   "spirv_exception_test.dart",
   "task_order_test.dart",
   "text_test.dart",

testing/dart/serial_gc_test.dart

@@ -0,0 +1,17 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// FlutterTesterOptions=--enable-serial-gc
+
+import 'package:litetest/litetest.dart';
+
+void main() {
+  test('Serial GC option test ', () async {
+    bool threw = false;
+    for (int i = 0; i < 100; i++) {
+      var a = <int>[100];
+    }
+    expect(threw, false);
+  });
+}