6 files changed, 54 insertions, 8 deletions

diff --git a/libartbase/base/flags.h b/libartbase/base/flags.h
index 4734a60568..cec6c584ff 100644
--- a/libartbase/base/flags.h
+++ b/libartbase/base/flags.h
@@ -311,6 +311,9 @@ struct Flags {
   // to logcat will be in human-readable text format.
   // Supported values are "text" and "xml".
   Flag<std::string> MetricsFormat{"metrics.format", "text", FlagType::kCmdlineOnly};
+
+  // Whether or not to force the metrics initialization.
+  Flag<bool> MetricsForceEnable{"metrics.force-enable", false, FlagType::kCmdlineOnly};
 };
 
 // This is the actual instance of all the flags.
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 989763022f..53c1cb152f 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -1278,7 +1278,7 @@ void Runtime::InitNonZygoteOrPostFork(
   heap_->ResetGcPerformanceInfo();
   GetMetrics()->Reset();
 
-  if (metrics_reporter_ != nullptr) {
+  if (AreMetricsInitialized()) {
     // Now that we know if we are an app or system server, reload the metrics reporter config
     // in case there are any difference.
     metrics::ReportingConfig metrics_config =
@@ -2112,7 +2112,12 @@ bool Runtime::Init(RuntimeArgumentMap&& runtime_options_in) {
   // Class-roots are setup, we can now finish initializing the JniIdManager.
   GetJniIdManager()->Init(self);
 
-  InitMetrics();
+  // Initialize metrics only for the Zygote process or
+  // if explicitly enabled via command line argument.
+  if (IsZygote() || gFlags.MetricsForceEnable.GetValue()) {
+    LOG(INFO) << "Initializing ART runtime metrics";
+    InitMetrics();
+  }
 
   // Runtime initialization is largely done now.
   // We load plugins first since that can modify the runtime state slightly.
@@ -2213,7 +2218,7 @@ void Runtime::InitMetrics() {
 }
 
 void Runtime::RequestMetricsReport(bool synchronous) {
-  if (metrics_reporter_) {
+  if (AreMetricsInitialized()) {
     metrics_reporter_->RequestMetricsReport(synchronous);
   }
 }
@@ -2871,7 +2876,7 @@ void Runtime::RegisterAppInfo(const std::string& package_name,
       ref_profile_filename,
       AppInfo::FromVMRuntimeConstants(code_type));
 
-  if (metrics_reporter_ != nullptr) {
+  if (AreMetricsInitialized()) {
     metrics_reporter_->NotifyAppInfoUpdated(&app_info_);
   }
 
@@ -3308,14 +3313,14 @@ bool Runtime::NotifyStartupCompleted() {
 
   ProfileSaver::NotifyStartupCompleted();
 
-  if (metrics_reporter_ != nullptr) {
+  if (AreMetricsInitialized()) {
     metrics_reporter_->NotifyStartupCompleted();
   }
   return true;
 }
 
 void Runtime::NotifyDexFileLoaded() {
-  if (metrics_reporter_ != nullptr) {
+  if (AreMetricsInitialized()) {
     metrics_reporter_->NotifyAppInfoUpdated(&app_info_);
   }
 }
diff --git a/runtime/runtime.h b/runtime/runtime.h
index afb8ebd3c0..64d85b6464 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -1132,6 +1132,8 @@ class Runtime {
     }
   }
 
+  bool AreMetricsInitialized() const { return metrics_reporter_ != nullptr; }
+
  private:
   static void InitPlatformSignalHandlers();
 
diff --git a/runtime/runtime_test.cc b/runtime/runtime_test.cc
index cd0c862d82..1faecf36a8 100644
--- a/runtime/runtime_test.cc
+++ b/runtime/runtime_test.cc
@@ -109,4 +109,32 @@ TEST_F(RuntimeTest, ElfAlignmentMismatch) {
   EXPECT_EQ(kElfSegmentAlignment, elf_file->GetElfSegmentAlignmentFromFile());
 }
 
+class RuntimeInitMetricsDefaultTest : public CommonRuntimeTest {};
+
+TEST_F(RuntimeInitMetricsDefaultTest, MetricsAreNotInitialized) {
+  ASSERT_FALSE(runtime_->AreMetricsInitialized());
+}
+
+class RuntimeInitMetricsZygoteTest : public CommonRuntimeTest {
+  void SetUpRuntimeOptions(RuntimeOptions* options) override {
+    CommonRuntimeTest::SetUpRuntimeOptions(options);
+    options->emplace_back(std::make_pair("-Xzygote", nullptr));
+  }
+};
+
+TEST_F(RuntimeInitMetricsZygoteTest, MetricsAreInitialized) {
+  ASSERT_TRUE(runtime_->AreMetricsInitialized());
+}
+
+class RuntimeInitMetricsForceEnableTest : public CommonRuntimeTest {
+  void SetUpRuntimeOptions(RuntimeOptions* options) override {
+    CommonRuntimeTest::SetUpRuntimeOptions(options);
+    options->emplace_back(std::make_pair("-Xmetrics-force-enable:true", nullptr));
+  }
+};
+
+TEST_F(RuntimeInitMetricsForceEnableTest, MetricsAreInitialized) {
+  ASSERT_TRUE(runtime_->AreMetricsInitialized());
+}
+
 }  // namespace art
diff --git a/test/2232-write-metrics-to-log/run.py b/test/2232-write-metrics-to-log/run.py
index 89fe040087..167c2bbc17 100644
--- a/test/2232-write-metrics-to-log/run.py
+++ b/test/2232-write-metrics-to-log/run.py
@@ -21,7 +21,10 @@ def run(ctx, args):
       android_log_tags="*:i",
       diff_min_log_tag="i",
       runtime_option=[
-          "-Xmetrics-write-to-logcat:true", "-Xmetrics-reporting-mods:100"
+          "-Xmetrics-force-enable:true",
+          "-Xmetrics-write-to-statsd:false",
+          "-Xmetrics-write-to-logcat:true",
+          "-Xmetrics-reporting-mods:100",
       ])
 
   # Check that one of the metrics appears in stderr.
diff --git a/test/2233-metrics-background-thread/run.py b/test/2233-metrics-background-thread/run.py
index e0d86ac13d..6b63488292 100644
--- a/test/2233-metrics-background-thread/run.py
+++ b/test/2233-metrics-background-thread/run.py
@@ -18,7 +18,12 @@ def run(ctx, args):
     args,
     android_log_tags="*:d",
     diff_min_log_tag="d",
-    runtime_option=["-Xmetrics-reporting-mods:100",]
+    runtime_option=[
+      "-Xmetrics-force-enable:true",
+      "-Xmetrics-write-to-statsd:false",
+      "-Xmetrics-write-to-logcat:true",
+      "-Xmetrics-reporting-mods:100",
+    ]
   )
 
   # Check that log messages from the metrics reporting thread appear in stderr.