From 9ae3098af8b28c1e554d9ab8cf8425a52e37ac7e Mon Sep 17 00:00:00 2001
From: Robert Maynard <robert.maynard@kitware.com>
Date: Tue, 14 Nov 2017 19:42:48 -0500
Subject: [PATCH] Give each thread using vtk a separate runtime device tracker

---
 vtkm/cont/RuntimeDeviceTracker.cxx | 21 +++++++++++++++++++--
 vtkm/cont/RuntimeDeviceTracker.h   |  6 +++---
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/vtkm/cont/RuntimeDeviceTracker.cxx b/vtkm/cont/RuntimeDeviceTracker.cxx
index 33ef3b43c..d0b31714e 100644
--- a/vtkm/cont/RuntimeDeviceTracker.cxx
+++ b/vtkm/cont/RuntimeDeviceTracker.cxx
@@ -29,7 +29,10 @@
 #include <vtkm/cont/tbb/DeviceAdapterTBB.h>
 
 #include <algorithm>
+#include <map>
+#include <mutex>
 #include <sstream>
+#include <thread>
 
 #define VTKM_MAX_DEVICE_ADAPTER_ID 8
 
@@ -155,8 +158,22 @@ void RuntimeDeviceTracker::ForceDeviceImpl(vtkm::cont::DeviceAdapterId deviceId,
 VTKM_CONT
 vtkm::cont::RuntimeDeviceTracker GetGlobalRuntimeDeviceTracker()
 {
-  static vtkm::cont::RuntimeDeviceTracker globalTracker;
-  return globalTracker;
+  static std::mutex mtx;
+  static std::map<std::thread::id, vtkm::cont::RuntimeDeviceTracker> globalTrackers;
+  std::thread::id this_id = std::this_thread::get_id();
+
+  std::unique_lock<std::mutex> lock(mtx);
+  auto iter = globalTrackers.find(this_id);
+  if (iter != globalTrackers.end())
+  {
+    return iter->second;
+  }
+  else
+  {
+    vtkm::cont::RuntimeDeviceTracker tracker;
+    globalTrackers[this_id] = tracker;
+    return tracker;
+  }
 }
 }
 } // namespace vtkm::cont
diff --git a/vtkm/cont/RuntimeDeviceTracker.h b/vtkm/cont/RuntimeDeviceTracker.h
index cf0f4ad8d..ebdfe5e72 100644
--- a/vtkm/cont/RuntimeDeviceTracker.h
+++ b/vtkm/cont/RuntimeDeviceTracker.h
@@ -207,13 +207,13 @@ private:
                        bool runtimeExists);
 };
 
-/// \brief Get the global \c RuntimeDeviceTracker.
+/// \brief Get the \c RuntimeDeviceTracker for the current thread.
 ///
 /// Many features in VTK-m will attempt to run algorithms on the "best
 /// available device." This often is determined at runtime as failures in
 /// one device are recorded and that device is disabled. To prevent having
-/// to check over and over again, VTK-m features generally use the global
-/// device adapter so that these choices are marked and shared.
+/// to check over and over again, VTK-m uses per thread runtime device tracker
+/// so that these choices are marked and shared.
 ///
 VTKM_CONT_EXPORT
 VTKM_CONT