[Core] Make Placement Group Wildcard and Indexed Resource Assignments…

… Consistent (ray-project#48088)

Signed-off-by: Mengjin Yan <mengjinyan3@gmail.com>

src/ray/common/bundle_spec.cc

@@ -95,15 +95,15 @@ std::string BundleSpecification::DebugString() const {
 }
 
 std::string FormatPlacementGroupResource(const std::string &original_resource_name,
-                                         const PlacementGroupID &group_id,
+                                         const std::string &group_id_hex,
                                          int64_t bundle_index) {
   std::stringstream os;
   if (bundle_index >= 0) {
     os << original_resource_name << kGroupKeyword << std::to_string(bundle_index) << "_"
-       << group_id.Hex();
+       << group_id_hex;
   } else {
     RAY_CHECK(bundle_index == -1) << "Invalid index " << bundle_index;
-    os << original_resource_name << kGroupKeyword << group_id.Hex();
+    os << original_resource_name << kGroupKeyword << group_id_hex;
   }
   std::string result = os.str();
   RAY_DCHECK(GetOriginalResourceName(result) == original_resource_name)
@@ -112,6 +112,13 @@ std::string FormatPlacementGroupResource(const std::string &original_resource_na
   return result;
 }
 
+std::string FormatPlacementGroupResource(const std::string &original_resource_name,
+                                         const PlacementGroupID &group_id,
+                                         int64_t bundle_index) {
+  return FormatPlacementGroupResource(
+      original_resource_name, group_id.Hex(), bundle_index);
+}
+
 std::string GetOriginalResourceName(const std::string &resource) {
   auto data = ParsePgFormattedResource(
       resource, /*for_wildcard_resource*/ true, /*for_indexed_resource*/ true);
@@ -146,6 +153,7 @@ std::optional<PgFormattedResourceData> ParsePgFormattedResource(
         match_groups.size() == 3) {
       data.original_resource = match_groups[1].str();
       data.bundle_index = -1;
+      data.group_id = match_groups[2].str();
       return data;
     }
   }
@@ -157,6 +165,7 @@ std::optional<PgFormattedResourceData> ParsePgFormattedResource(
         match_groups.size() == 4) {
       data.original_resource = match_groups[1].str();
       data.bundle_index = stoi(match_groups[2].str());
+      data.group_id = match_groups[3].str();
       return data;
     }
   }

src/ray/common/bundle_spec.h

@@ -97,8 +97,22 @@ struct PgFormattedResourceData {
   std::string original_resource;
   /// -1 if it is a wildcard resource.
   int64_t bundle_index;
+  std::string group_id;
 };
 
+/// Format a placement group resource with provided parameters.
+///
+/// \param original_resource_name The original resource name of the pg resource.
+/// \param group_id_str The group id in string format.
+/// \param bundle_index The bundle index. If -1, generate the wildcard pg resource.
+///                     E.g., [original_resource_name]_group_[group_id_str].
+///                     If >=0, generate the indexed pg resource. E.g.,
+///                     [original_resource_name]_group_[bundle_index]_[group_id_str]
+/// \return The corresponding formatted placement group resource string.
+std::string FormatPlacementGroupResource(const std::string &original_resource_name,
+                                         const std::string &group_id_hex,
+                                         int64_t bundle_index = -1);
+
 /// Format a placement group resource, e.g., CPU -> CPU_group_i
 std::string FormatPlacementGroupResource(const std::string &original_resource_name,
                                          const PlacementGroupID &group_id,

src/ray/common/scheduling/resource_instance_set.cc

@@ -16,7 +16,9 @@
 
 #include <cmath>
 #include <sstream>
+#include <utility>
 
+#include "ray/common/bundle_spec.h"
 #include "ray/util/logging.h"
 
 namespace ray {
@@ -43,6 +45,29 @@ bool NodeResourceInstanceSet::Has(ResourceID resource_id) const {
 
 void NodeResourceInstanceSet::Remove(ResourceID resource_id) {
   resources_.erase(resource_id);
+
+  // Remove from the pg_indexed_resources_ as well
+  auto data = ParsePgFormattedResource(resource_id.Binary(),
+                                       /*for_wildcard_resource=*/false,
+                                       /*for_indexed_resource=*/true);
+  if (data) {
+    ResourceID original_resource_id(data->original_resource);
+
+    auto pg_resource_map_it = pg_indexed_resources_.find(original_resource_id);
+    if (pg_resource_map_it != pg_indexed_resources_.end()) {
+      auto resource_set_it = pg_resource_map_it->second.find(data->group_id);
+
+      if (resource_set_it != pg_resource_map_it->second.end()) {
+        resource_set_it->second.erase(resource_id);
+        if (resource_set_it->second.empty()) {
+          pg_resource_map_it->second.erase(data->group_id);
+        }
+        if (pg_resource_map_it->second.empty()) {
+          pg_indexed_resources_.erase(original_resource_id);
+        }
+      }
+    }
+  }
 }
 
 const std::vector<FixedPoint> &NodeResourceInstanceSet::Get(
@@ -69,6 +94,24 @@ NodeResourceInstanceSet &NodeResourceInstanceSet::Set(ResourceID resource_id,
     resources_.erase(resource_id);
   } else {
     resources_[resource_id] = std::move(instances);
+
+    // Popluate the pg_indexed_resources_map_
+    // TODO (myan): The parsing of the resource_id String can be costly and impact the
+    // task creation throughput if the parting is required every time we allocate
+    // resources for a task and updating the available resources. The current benchmark
+    // shows no observable impact for now. But in the furture, ideas of improvement are:
+    // (1) to add the placement group id as well as the bundle index inside the
+    // ResourceID class. And instead of parse the String, leveraging the fields in the
+    // ResourceID class directly; (2) to update the pg resource id format to start with
+    // a special prefix so that we can do "startwith" instead of regex match which is
+    // less costly
+    auto data = ParsePgFormattedResource(resource_id.Binary(),
+                                         /*for_wildcard_resource=*/false,
+                                         /*for_indexed_resource=*/true);
+    if (data) {
+      pg_indexed_resources_[ResourceID(data->original_resource)][data->group_id].emplace(
+          resource_id);
+    }
   }
   return *this;
 }
@@ -93,21 +136,156 @@ bool NodeResourceInstanceSet::operator==(const NodeResourceInstanceSet &other) c
 std::optional<absl::flat_hash_map<ResourceID, std::vector<FixedPoint>>>
 NodeResourceInstanceSet::TryAllocate(const ResourceSet &resource_demands) {
   absl::flat_hash_map<ResourceID, std::vector<FixedPoint>> allocations;
+
+  // During resource allocation with a placement group, no matter whether the allocation
+  // requirement specifies a bundle index, we generate the allocation on both
+  // the wildcard resource and the indexed resource. The resource_demand shouldn't be
+  // assigned across bundles. And If no bundle index is specified, we will iterate
+  // through the bundles and find the first bundle that can fit the required resources.
+  // In addition, for unit resources, we make sure that the allocation on the
+  // wildcard resource and the indexed resource are consistent, meaning the same
+  // instance ids should be allocated.
+  //
+  // For example, considering the GPU resource on a host. Assuming the host has 3 GPUs
+  // and 1 placement group with 2 bundles. The bundle with index 1 contains 1 GPU and
+  // the bundle with index 2 contains 2 GPU.
+  //
+  // The current node resource can be as follows:
+  // resource id: total, available
+  // GPU: [1, 1, 1], [0, 0, 0]
+  // GPU_<pg_id>: [1, 1, 1], [1, 1, 1]
+  // GPU_1_<pg_id>: [1, 0, 0], [1, 0, 0]
+  // GPU_2_<pg_id>: [0, 1, 1], [0, 1, 1]
+  //
+  // Now, we want to allocate a task with 2 GPUs and in the placement group <pg_id>,
+  // reflecting in the following resource demand:
+  // GPU_<pg_id> : 2
+  //
+  // We will iterate though all the bundles in the placement group and bundle with
+  // index=2 has the required capacity. So we will allocate the task to the 2 GPUs in
+  // bundle 2 in placement group <pg_id> and the same allocation should be reflected in
+  // the wildcard GPU resource. So the allocation will be:
+  // GPU_<pg_id> : [0, 1, 1]
+  // GPU_2_<pg_id> : [0, 1, 1]
+  //
+  // And as a result, after the allocation, current node resource will be:
+  // resource id: total, available
+  // GPU: [1, 1, 1], [0, 0, 0]
+  // GPU_<pg_id>: [1, 1, 1], [1, 0, 0]
+  // GPU_1_<pg_id>: [1, 0, 0], [1, 0, 0]
+  // GPU_2_<pg_id>: [0, 1, 1], [0, 0, 0]
+
+  absl::flat_hash_map</* original resource id (GPU, CPU, etc.) */ ResourceID,
+                      std::vector<std::pair</* actual resource id */ ResourceID,
+                                            PgFormattedResourceData>>>
+      pg_resource_map;
+
   for (const auto &[resource_id, demand] : resource_demands.Resources()) {
-    auto allocation = TryAllocate(resource_id, demand);
-    if (allocation) {
-      // Even if allocation failed we need to remember partial allocations to correctly
-      // free resources.
-      allocations[resource_id] = std::move(*allocation);
+    auto data = ParsePgFormattedResource(resource_id.Binary(),
+                                         /*for_wildcard_resource*/ true,
+                                         /*for_indexed_resource*/ true);
+
+    if (data) {
+      // Aggregate based on resource type
+      ResourceID original_resource_id{data->original_resource};
+      pg_resource_map[original_resource_id].push_back(
+          std::make_pair(resource_id, data.value()));
     } else {
-      // Allocation failed. Restore partially allocated resources.
-      for (const auto &[resource_id, allocation] : allocations) {
-        Free(resource_id, allocation);
+      // Directly allocate the resources if the resource is not with a placement group
+      auto allocation = TryAllocate(resource_id, demand);
+      if (allocation) {
+        // Even if allocation failed we need to remember partial allocations to
+        // correctly free resources.
+        allocations[resource_id] = std::move(*allocation);
+      } else {
+        // Allocation failed. Restore partially allocated resources.
+        for (const auto &[resource_id, allocation] : allocations) {
+          Free(resource_id, allocation);
+        }
+        return std::nullopt;
       }
-      return std::nullopt;
     }
   }
 
+  // Handle the resource allocation for resources with placement group
+  for (const auto &[original_resource_id, resource_id_vector] : pg_resource_map) {
+    // Assuming exactly 1 placement group and at most 1 bundle index can be specified in
+    // the resource requirement for a single resource type
+    // Also assuming the wildcard resource id will always exist in the resource_demands
+    // no matter how the resource requirement is specified in task
+    std::optional<std::vector<FixedPoint>> wildcard_allocation;
+    const ResourceID *wildcard_resource_id = nullptr;
+    const std::string *pg_id = nullptr;
+
+    // Allocate indexed resource
+    if (resource_id_vector.size() == 1) {
+      // The case where no bundle index is specified
+      // Iterate through the bundles with the same original resource and pg_id to find
+      // the first one with enough space
+      bool found = false;
+      wildcard_resource_id = &resource_id_vector[0].first;
+      pg_id = &resource_id_vector[0].second.group_id;
+
+      auto pg_index_resources_it = pg_indexed_resources_.find(original_resource_id);
+      if (pg_index_resources_it != pg_indexed_resources_.end()) {
+        auto index_resources_it = pg_index_resources_it->second.find(*pg_id);
+        if (index_resources_it != pg_index_resources_it->second.end()) {
+          for (ResourceID indexed_resource_id : index_resources_it->second) {
+            if (Has(indexed_resource_id)) {
+              wildcard_allocation = TryAllocate(
+                  indexed_resource_id, resource_demands.Get(*wildcard_resource_id));
+              if (wildcard_allocation) {
+                // Found the allocation in a bundle
+                allocations[indexed_resource_id] = *wildcard_allocation;
+                found = true;
+                break;
+              }
+            }
+          }
+        }
+      }
+
+      if (!found) {
+        // No bundle can fit the required resources, allocation failed
+        for (const auto &[resource_id, allocation] : allocations) {
+          Free(resource_id, allocation);
+        }
+        return std::nullopt;
+      }
+    } else {
+      // The case where the bundle index is specified
+      // For each resource type, both the wildcard resource and the indexed resource
+      // should be in the resource_demand
+      for (const std::pair<ResourceID, PgFormattedResourceData> &pair :
+           resource_id_vector) {
+        if (pair.second.bundle_index != -1) {
+          // This is the indexed resource
+          wildcard_allocation = TryAllocate(pair.first, resource_demands.Get(pair.first));
+
+          if (wildcard_allocation) {
+            allocations[pair.first] = *wildcard_allocation;
+          } else {
+            // The corresponding bundle cannot hold the required resources.
+            // Allocation failed
+            for (const auto &[resource_id, allocation] : allocations) {
+              Free(resource_id, allocation);
+            }
+            return std::nullopt;
+          }
+        } else {
+          // This is the wildcard resource
+          wildcard_resource_id = &pair.first;
+        }
+      }
+    }
+
+    // Allocate wildcard resource, should be consistent with the indexed resource
+    RAY_CHECK(wildcard_resource_id != nullptr);
+    RAY_CHECK(!(*wildcard_allocation).empty());
+    AllocateWithReference(*wildcard_allocation, *wildcard_resource_id);
+    allocations[*wildcard_resource_id] = std::move(*wildcard_allocation);
+  }
+
   return std::make_optional<absl::flat_hash_map<ResourceID, std::vector<FixedPoint>>>(
       std::move(allocations));
 }
@@ -139,7 +317,7 @@ std::optional<std::vector<FixedPoint>> NodeResourceInstanceSet::TryAllocate(
   //
   // As long as remaining_demand is greater than 1.,
   // allocate full unit-capacity instances until the remaining_demand becomes fractional.
-  // Then try to find the best fit for the fractional remaining_resources. Best fist means
+  // Then try to find the best fit for the fractional remaining_resources. Best fit means
   // allocating the resource instance with the smallest available capacity greater than
   // remaining_demand
   if (remaining_demand >= 1.) {
@@ -186,6 +364,20 @@ std::optional<std::vector<FixedPoint>> NodeResourceInstanceSet::TryAllocate(
   return std::make_optional<std::vector<FixedPoint>>(std::move(allocation));
 }
 
+void NodeResourceInstanceSet::AllocateWithReference(
+    const std::vector<FixedPoint> &ref_allocation, ResourceID resource_id) {
+  std::vector<FixedPoint> available = Get(resource_id);
+  RAY_CHECK(!available.empty());
+  RAY_CHECK_EQ(available.size(), ref_allocation.size());
+
+  for (size_t i = 0; i < ref_allocation.size(); i++) {
+    RAY_CHECK_GE(available[i], ref_allocation[i]);
+    available[i] -= ref_allocation[i];
+  }
+
+  Set(resource_id, std::move(available));
+}
+
 void NodeResourceInstanceSet::Free(ResourceID resource_id,
                                    const std::vector<FixedPoint> &allocation) {
   std::vector<FixedPoint> available = Get(resource_id);