speed up random sample of graph engine (#34088)

paddle/fluid/distributed/table/common_graph_table.cc

@@ -15,12 +15,15 @@
 #include "paddle/fluid/distributed/table/common_graph_table.h"
 #include <time.h>
 #include <algorithm>
+#include <chrono>
 #include <set>
 #include <sstream>
 #include "paddle/fluid/distributed/common/utils.h"
 #include "paddle/fluid/distributed/table/graph/graph_node.h"
+#include "paddle/fluid/framework/generator.h"
 #include "paddle/fluid/string/printf.h"
 #include "paddle/fluid/string/string_helper.h"
+
 namespace paddle {
 namespace distributed {
 
@@ -399,15 +402,18 @@ int32_t GraphTable::random_sample_neighboors(
     uint64_t &node_id = node_ids[idx];
     std::unique_ptr<char[]> &buffer = buffers[idx];
     int &actual_size = actual_sizes[idx];
-    tasks.push_back(_shards_task_pool[get_thread_pool_index(node_id)]->enqueue(
-        [&]() -> int {
+
+    int thread_pool_index = get_thread_pool_index(node_id);
+    auto rng = _shards_task_rng_pool[thread_pool_index];
+
+    tasks.push_back(_shards_task_pool[thread_pool_index]->enqueue([&]() -> int {
       Node *node = find_node(node_id);
 
       if (node == nullptr) {
         actual_size = 0;
         return 0;
       }
-          std::vector<int> res = node->sample_k(sample_size);
+      std::vector<int> res = node->sample_k(sample_size, rng);
       actual_size = res.size() * (Node::id_size + Node::weight_size);
       int offset = 0;
       uint64_t id;
@@ -512,7 +518,6 @@ int32_t GraphTable::pull_graph_list(int start, int total_size,
     int end = start + (count - 1) * step + 1;
     tasks.push_back(_shards_task_pool[i % task_pool_size_]->enqueue(
         [this, i, start, end, step, size]() -> std::vector<Node *> {
-
           return this->shards[i].get_batch(start - size, end - size, step);
         }));
     start += count * step;
@@ -546,6 +551,7 @@ int32_t GraphTable::initialize() {
   _shards_task_pool.resize(task_pool_size_);
   for (size_t i = 0; i < _shards_task_pool.size(); ++i) {
     _shards_task_pool[i].reset(new ::ThreadPool(1));
+    _shards_task_rng_pool.push_back(paddle::framework::GetCPURandomEngine(0));
   }
   server_num = _shard_num;
   // VLOG(0) << "in init graph table server num = " << server_num;
@@ -586,5 +592,5 @@ int32_t GraphTable::initialize() {
   shards = std::vector<GraphShard>(shard_num_per_table, GraphShard(shard_num));
   return 0;
 }
-}
-};
+}  // namespace distributed
+};  // namespace paddle

paddle/fluid/distributed/table/common_graph_table.h

@@ -136,6 +136,7 @@ class GraphTable : public SparseTable {
   std::string table_type;
 
   std::vector<std::shared_ptr<::ThreadPool>> _shards_task_pool;
+  std::vector<std::shared_ptr<std::mt19937_64>> _shards_task_rng_pool;
 };
 }  // namespace distributed
 

paddle/fluid/distributed/table/graph/graph_node.cc

@@ -113,5 +113,5 @@ void FeatureNode::recover_from_buffer(char* buffer) {
     feature.push_back(std::string(str));
   }
 }
-}
-}
+}  // namespace distributed
+}  // namespace paddle

paddle/fluid/distributed/table/graph/graph_node.h

@@ -15,6 +15,7 @@
 #pragma once
 #include <cstring>
 #include <iostream>
+#include <memory>
 #include <sstream>
 #include <vector>
 #include "paddle/fluid/distributed/table/graph/graph_weighted_sampler.h"
@@ -33,7 +34,10 @@ class Node {
   virtual void build_edges(bool is_weighted) {}
   virtual void build_sampler(std::string sample_type) {}
   virtual void add_edge(uint64_t id, float weight) {}
-  virtual std::vector<int> sample_k(int k) { return std::vector<int>(); }
+  virtual std::vector<int> sample_k(
+      int k, const std::shared_ptr<std::mt19937_64> rng) {
+    return std::vector<int>();
+  }
   virtual uint64_t get_neighbor_id(int idx) { return 0; }
   virtual float get_neighbor_weight(int idx) { return 1.; }
 
@@ -59,7 +63,10 @@ class GraphNode : public Node {
   virtual void add_edge(uint64_t id, float weight) {
     edges->add_edge(id, weight);
   }
-  virtual std::vector<int> sample_k(int k) { return sampler->sample_k(k); }
+  virtual std::vector<int> sample_k(
+      int k, const std::shared_ptr<std::mt19937_64> rng) {
+    return sampler->sample_k(k, rng);
+  }
   virtual uint64_t get_neighbor_id(int idx) { return edges->get_id(idx); }
   virtual float get_neighbor_weight(int idx) { return edges->get_weight(idx); }
 
@@ -123,5 +130,5 @@ class FeatureNode : public Node {
  protected:
   std::vector<std::string> feature;
 };
-}
-}
+}  // namespace distributed
+}  // namespace paddle

paddle/fluid/distributed/table/graph/graph_weighted_sampler.cc

@@ -14,24 +14,30 @@
 
 #include "paddle/fluid/distributed/table/graph/graph_weighted_sampler.h"
 #include <iostream>
+#include <memory>
 #include <unordered_map>
+#include "paddle/fluid/framework/generator.h"
 namespace paddle {
 namespace distributed {
 
 void RandomSampler::build(GraphEdgeBlob *edges) { this->edges = edges; }
 
-std::vector<int> RandomSampler::sample_k(int k) {
+std::vector<int> RandomSampler::sample_k(
+    int k, const std::shared_ptr<std::mt19937_64> rng) {
   int n = edges->size();
-  if (k > n) {
+  if (k >= n) {
     k = n;
+    std::vector<int> sample_result;
+    for (int i = 0; i < k; i++) {
+      sample_result.push_back(i);
+    }
+    return sample_result;
   }
-  struct timespec tn;
-  clock_gettime(CLOCK_REALTIME, &tn);
-  srand(tn.tv_nsec);
   std::vector<int> sample_result;
   std::unordered_map<int, int> replace_map;
   while (k--) {
-    int rand_int = rand() % n;
+    std::uniform_int_distribution<int> distrib(0, n - 1);
+    int rand_int = distrib(*rng);
     auto iter = replace_map.find(rand_int);
     if (iter == replace_map.end()) {
       sample_result.push_back(rand_int);
@@ -98,19 +104,23 @@ void WeightedSampler::build_one(WeightedGraphEdgeBlob *edges, int start,
     count = left->count + right->count;
   }
 }
-std::vector<int> WeightedSampler::sample_k(int k) {
-  if (k > count) {
+std::vector<int> WeightedSampler::sample_k(
+    int k, const std::shared_ptr<std::mt19937_64> rng) {
+  if (k >= count) {
     k = count;
+    std::vector<int> sample_result;
+    for (int i = 0; i < k; i++) {
+      sample_result.push_back(i);
+    }
+    return sample_result;
   }
   std::vector<int> sample_result;
   float subtract;
   std::unordered_map<WeightedSampler *, float> subtract_weight_map;
   std::unordered_map<WeightedSampler *, int> subtract_count_map;
-  struct timespec tn;
-  clock_gettime(CLOCK_REALTIME, &tn);
-  srand(tn.tv_nsec);
+  std::uniform_real_distribution<float> distrib(0, 1.0);
   while (k--) {
-    float query_weight = rand() % 100000 / 100000.0;
+    float query_weight = distrib(*rng);
     query_weight *= weight - subtract_weight_map[this];
     sample_result.push_back(sample(query_weight, subtract_weight_map,
                                    subtract_count_map, subtract));
@@ -146,5 +156,5 @@ int WeightedSampler::sample(
   subtract_count_map[this]++;
   return return_idx;
 }
-}
-}
+}  // namespace distributed
+}  // namespace paddle

paddle/fluid/distributed/table/graph/graph_weighted_sampler.h

@@ -14,6 +14,8 @@
 
 #pragma once
 #include <ctime>
+#include <memory>
+#include <random>
 #include <unordered_map>
 #include <vector>
 #include "paddle/fluid/distributed/table/graph/graph_edge.h"
@@ -24,14 +26,16 @@ class Sampler {
  public:
   virtual ~Sampler() {}
   virtual void build(GraphEdgeBlob *edges) = 0;
-  virtual std::vector<int> sample_k(int k) = 0;
+  virtual std::vector<int> sample_k(
+      int k, const std::shared_ptr<std::mt19937_64> rng) = 0;
 };
 
 class RandomSampler : public Sampler {
  public:
   virtual ~RandomSampler() {}
   virtual void build(GraphEdgeBlob *edges);
-  virtual std::vector<int> sample_k(int k);
+  virtual std::vector<int> sample_k(int k,
+                                    const std::shared_ptr<std::mt19937_64> rng);
   GraphEdgeBlob *edges;
 };
 
@@ -46,7 +50,8 @@ class WeightedSampler : public Sampler {
   GraphEdgeBlob *edges;
   virtual void build(GraphEdgeBlob *edges);
   virtual void build_one(WeightedGraphEdgeBlob *edges, int start, int end);
-  virtual std::vector<int> sample_k(int k);
+  virtual std::vector<int> sample_k(int k,
+                                    const std::shared_ptr<std::mt19937_64> rng);
 
  private:
   int sample(float query_weight,
@@ -54,5 +59,5 @@ class WeightedSampler : public Sampler {
              std::unordered_map<WeightedSampler *, int> &subtract_count_map,
              float &subtract);
 };
-}
-}
+}  // namespace distributed
+}  // namespace paddle