Prevent ResourceSet with zero CPUs from appearing.

src/ray/raylet/scheduling_resources.cc

@@ -76,7 +76,11 @@ ResourceSet::ResourceSet() {}
 
 ResourceSet::ResourceSet(
     const std::unordered_map<std::string, FractionalResourceQuantity> &resource_map)
-    : resource_capacity_(resource_map) {}
+    : resource_capacity_(resource_map) {
+      for (auto const &resource_pair : resource_map) {
+        RAY_CHECK(resource_pair.second > 0);
+      }
+    }
 
 ResourceSet::ResourceSet(const std::unordered_map<std::string, double> &resource_map) {
   for (auto const &resource_pair : resource_map) {
@@ -169,7 +173,8 @@ void ResourceSet::SubtractResourcesStrict(const ResourceSet &other) {
     const std::string &resource_label = resource_pair.first;
     const FractionalResourceQuantity &resource_capacity = resource_pair.second;
     RAY_CHECK(resource_capacity_.count(resource_label) == 1)
-        << "Attempt to acquire unknown resource: " << resource_label << " capacity " << resource_capacity.ToDouble();
+        << "Attempt to acquire unknown resource: " << resource_label << " capacity "
+        << resource_capacity.ToDouble();
     resource_capacity_[resource_label] -= resource_capacity;
 
     // Ensure that quantity is positive. Note, we have to have the check before
@@ -233,8 +238,10 @@ FractionalResourceQuantity ResourceSet::GetResource(
 
 const ResourceSet ResourceSet::GetNumCpus() const {
   ResourceSet cpu_resource_set;
-  cpu_resource_set.resource_capacity_[kCPU_ResourceLabel] =
-      GetResource(kCPU_ResourceLabel);
+  const FractionalResourceQuantity cpu_quantity = GetResource(kCPU_ResourceLabel);
+  if (cpu_quantity > 0) {
+    cpu_resource_set.resource_capacity_[kCPU_ResourceLabel] = cpu_quantity;
+  }
   return cpu_resource_set;
 }