Stop dividing the command-line-provided number of test jobs by 2.

The value should be half of the number of CPU cores or whatever
--test-launcher-jobs says. This change makes base::NumParallelJobs
return the number of CPU cores divided by a cores_per_job factor
supplied by each caller.

This also adds error checking on the result where it wasn't already
present.



Bug: 1096909
Change-Id: I7c5bbf15697157993ebe07667e243201f6808fe5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2251568
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Ilia Samsonov <isamsonov@google.com>
Reviewed-by: Mostyn Bramley-Moore <mostynb@chromium.org>
Commit-Queue: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#784687}

base/test/launcher/test_launcher.cc

@@ -1837,7 +1837,7 @@ void TestLauncher::OnOutputTimeout() {
   watchdog_timer_.Reset();
 }
 
-size_t NumParallelJobs() {
+size_t NumParallelJobs(unsigned int cores_per_job) {
   const CommandLine* command_line = CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kTestLauncherJobs)) {
     // If the number of test launcher jobs was specified, return that number.
@@ -1860,15 +1860,15 @@ size_t NumParallelJobs() {
     return 1U;
   }
 
-  // Default to the number of processor cores.
 #if defined(OS_WIN)
   // Use processors in all groups (Windows splits more than 64 logical
   // processors into groups).
-  return base::checked_cast<size_t>(
+  size_t cores = base::checked_cast<size_t>(
       ::GetActiveProcessorCount(ALL_PROCESSOR_GROUPS));
 #else
-  return base::checked_cast<size_t>(SysInfo::NumberOfProcessors());
+  size_t cores = base::checked_cast<size_t>(SysInfo::NumberOfProcessors());
 #endif
+  return std::max(size_t(1), cores / cores_per_job);
 }
 
 std::string GetTestOutputSnippet(const TestResult& result,

base/test/launcher/test_launcher.h

@@ -312,7 +312,7 @@ class TestLauncher {
 };
 
 // Return the number of parallel jobs to use, or 0U in case of error.
-size_t NumParallelJobs();
+size_t NumParallelJobs(unsigned int cores_per_job);
 
 // Extract part from |full_output| that applies to |result|.
 std::string GetTestOutputSnippet(const TestResult& result,

base/test/launcher/unit_test_launcher.cc

@@ -228,7 +228,7 @@ int LaunchUnitTests(int argc,
                     RunTestSuiteCallback run_test_suite,
                     size_t retry_limit) {
   CommandLine::Init(argc, argv);
-  size_t parallel_jobs = NumParallelJobs();
+  size_t parallel_jobs = NumParallelJobs(/*cores_per_job=*/1);
   if (parallel_jobs == 0U) {
     return 1;
   }
@@ -265,7 +265,7 @@ int LaunchUnitTests(int argc,
                     RunTestSuiteCallback run_test_suite) {
   // Windows CommandLine::Init ignores argv anyway.
   CommandLine::Init(argc, NULL);
-  size_t parallel_jobs = NumParallelJobs();
+  size_t parallel_jobs = NumParallelJobs(/*cores_per_job=*/1);
   if (parallel_jobs == 0U) {
     return 1;
   }

chrome/test/base/browser_tests_main.cc

@@ -17,12 +17,9 @@
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
-  size_t parallel_jobs = base::NumParallelJobs();
-  if (parallel_jobs == 0U) {
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/2);
+  if (parallel_jobs == 0U)
     return 1;
-  } else if (parallel_jobs > 1U) {
-    parallel_jobs /= 2U;
-  }
 
 #if defined(OS_WIN)
   // Many tests validate code that requires user32.dll to be loaded. Loading it,

chrome/test/base/browser_tests_main_chromeos.cc

@@ -40,12 +40,9 @@ class BrowserTestSuiteRunnerChromeOS : public ChromeTestSuiteRunner {
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
-  size_t parallel_jobs = base::NumParallelJobs();
-  if (parallel_jobs == 0U) {
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/2);
+  if (parallel_jobs == 0U)
     return 1;
-  } else if (parallel_jobs > 1U) {
-    parallel_jobs /= 2U;
-  }
 
   BrowserTestSuiteRunnerChromeOS runner;
   ChromeTestLauncherDelegate delegate(&runner);

chromecast/app/cast_test_launcher.cc

@@ -45,10 +45,9 @@ class CastTestLauncherDelegate : public content::TestLauncherDelegate {
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
-  size_t parallel_jobs = base::NumParallelJobs();
-  if (parallel_jobs > 1U) {
-    parallel_jobs /= 2U;
-  }
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/2);
+  if (parallel_jobs == 0U)
+    return 1;
   chromecast::shell::CastTestLauncherDelegate launcher_delegate;
   mojo::core::Init();
   content::ForceInProcessNetworkService(true);

content/test/content_test_launcher.cc

@@ -78,10 +78,10 @@ class ContentTestLauncherDelegate : public TestLauncherDelegate {
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
-  size_t parallel_jobs = base::NumParallelJobs();
-  if (parallel_jobs > 1U) {
-    parallel_jobs /= 2U;
-  }
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/2);
+  if (parallel_jobs == 0U)
+    return 1;
+
 #if defined(OS_WIN)
   // Load and pin user32.dll to avoid having to load it once tests start while
   // on the main thread loop where blocking calls are disallowed.

extensions/shell/test/shell_tests_main.cc

@@ -9,10 +9,9 @@
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
-  size_t parallel_jobs = base::NumParallelJobs();
-  if (parallel_jobs > 1U) {
-    parallel_jobs /= 2U;
-  }
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/2);
+  if (parallel_jobs == 0U)
+    return 1;
   extensions::AppShellTestLauncherDelegate launcher_delegate;
   return content::LaunchTests(&launcher_delegate, parallel_jobs, argc, argv);
 }

fuchsia/engine/test/web_engine_test_launcher.cc

@@ -54,10 +54,9 @@ int main(int argc, char** argv) {
   command_line->AppendSwitchASCII(switches::kEnableLogging, "stderr");
   command_line->AppendSwitch(switches::kDisableGpu);
 
-  size_t parallel_jobs = base::NumParallelJobs();
-  if (parallel_jobs > 1U) {
-    parallel_jobs /= 2U;
-  }
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/2);
+  if (parallel_jobs == 0U)
+    return 1;
   ::WebEngineTestLauncherDelegate launcher_delegate;
   return LaunchTests(&launcher_delegate, parallel_jobs, argc, argv);
 }

headless/test/headless_test_launcher.cc

@@ -65,10 +65,9 @@ class HeadlessTestLauncherDelegate : public content::TestLauncherDelegate {
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
-  size_t parallel_jobs = base::NumParallelJobs();
-  if (parallel_jobs > 1U) {
-    parallel_jobs /= 2U;
-  }
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/2);
+  if (parallel_jobs == 0U)
+    return 1;
 
   // Setup a working test environment for the network service in case it's used.
   // Only create this object in the utility process, so that its members don't

weblayer/test/browsertests_main.cc

@@ -12,7 +12,9 @@
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
-  size_t parallel_jobs = base::NumParallelJobs();
+  size_t parallel_jobs = base::NumParallelJobs(/*cores_per_job=*/1);
+  if (parallel_jobs == 0U)
+    return 1;
 
   // Set up a working test environment for the network service in case it's
   // used. Only create this object in the utility process, so that its members