ctest: Optionally avoid starting tests that may exceed a given CPU load

Add a TestLoad setting to CTest that can be set via a new --test-load
command-line option, CTEST_TEST_LOAD variable, or TEST_LOAD option to
the ctest_test command.  Teach cmCTestMultiProcessHandler to measure
the CPU load and avoid starting tests that may take more than the
spare load currently available.  The expression

 <current_load> + <test_processors> <= <max-load>

must be true to start a new test.

Co-Author: Zack Galbreath <zack.galbreath@kitware.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/Source/cmCTest.cxx b/Source/cmCTest.cxx
index e3b7a2b..5887ba8 100644
--- a/Source/cmCTest.cxx
+++ b/Source/cmCTest.cxx
@@ -294,6 +294,7 @@ cmCTest::cmCTest()
   this->LabelSummary           = true;
   this->ParallelLevel          = 1;
   this->ParallelLevelSetInCli  = false;
+  this->TestLoad               = 0;
   this->SubmitIndex            = 0;
   this->Failover               = false;
   this->BatchJobs              = false;
@@ -393,6 +394,11 @@ void cmCTest::SetParallelLevel(int level)
   this->ParallelLevel = level < 1 ? 1 : level;
 }
 
+void cmCTest::SetTestLoad(unsigned long load)
+{
+  this->TestLoad = load;
+}
+
 //----------------------------------------------------------------------------
 bool cmCTest::ShouldCompressTestOutput()
 {
@@ -820,6 +826,20 @@ bool cmCTest::UpdateCTestConfiguration()
     cmSystemTools::ChangeDirectory(this->BinaryDir);
     }
   this->TimeOut = atoi(this->GetCTestConfiguration("TimeOut").c_str());
+  std::string const& testLoad = this->GetCTestConfiguration("TestLoad");
+  if (!testLoad.empty())
+    {
+    unsigned long load;
+    if (cmSystemTools::StringToULong(testLoad.c_str(), &load))
+      {
+      this->SetTestLoad(load);
+      }
+    else
+      {
+      cmCTestLog(this, WARNING, "Invalid value for 'Test Load' : "
+          << testLoad << std::endl);
+      }
+    }
   if ( this->ProduceXML )
     {
     this->CompressXMLFiles = cmSystemTools::IsOn(
@@ -2051,6 +2071,21 @@ bool cmCTest::HandleCommandLineArguments(size_t &i,
       }
     }
 
+  if(this->CheckArgument(arg, "--test-load") && i < args.size() - 1)
+    {
+    i++;
+    unsigned long load;
+    if (cmSystemTools::StringToULong(args[i].c_str(), &load))
+      {
+      this->SetTestLoad(load);
+      }
+    else
+      {
+      cmCTestLog(this, WARNING,
+                 "Invalid value for 'Test Load' : " << args[i] << std::endl);
+      }
+    }
+
   if(this->CheckArgument(arg, "--no-compress-output"))
     {
     this->CompressTestOutput = false;