Merge pull request #1926 from alicevision/dev/parallelization

Add parallelization tool to optimize chunk computation distribution

Author: cbentejac

meshroom/aliceVision/RelativePoseEstimating.py

@@ -8,7 +8,7 @@ class RelativePoseEstimating(desc.AVCommandLineNode):
     size = desc.DynamicNodeSize("input")
 
     parallelization = desc.Parallelization(blockSize=25)
-    commandLineRange = "--rangeStart {rangeStart} --rangeSize {rangeBlockSize}"
+    commandLineRange = "--rangeIteration {rangeIteration} --rangeBlocksCount {rangeBlocksCount}"
 
     category = "Sparse Reconstruction"
     documentation = """Estimate relative pose between each pair of views that share tracks."""

src/aliceVision/system/CMakeLists.txt

@@ -9,6 +9,7 @@ set(system_files_headers
     ProgressDisplay.hpp
     nvtx.hpp
     hardwareContext.hpp
+    Parallelization.hpp
 )
 
 # Sources
@@ -20,6 +21,7 @@ set(system_files_sources
     ProgressDisplay.cpp
     nvtx.cpp
     hardwareContext.cpp
+    Parallelization.cpp
 )
 
 alicevision_add_library(aliceVision_system

src/aliceVision/system/Parallelization.cpp

@@ -0,0 +1,44 @@
+// This file is part of the AliceVision project.
+// Copyright (c) 2025 AliceVision contributors.
+// This Source Code Form is subject to the terms of the Mozilla Public License,
+// v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#pragma once
+
+#include <aliceVision/system/Logger.hpp>
+#include <aliceVision/system/Parallelization.hpp>
+
+namespace aliceVision {
+
+bool rangeComputation(int & rangeStart, int & rangeEnd, int rangeIteration, int rangeBlocksCount, int itemsCount)
+{
+    rangeIteration = std::max(0, rangeIteration);
+    rangeBlocksCount = std::max(1, rangeBlocksCount);
+
+    if (itemsCount <= rangeBlocksCount)
+    {
+        //Just split 1 per iteration
+        rangeStart = rangeIteration;
+        rangeEnd = rangeStart + 1;
+    }
+    else
+    {
+        // Distribute data among available chunks
+        const int chunkSize = itemsCount / rangeBlocksCount;
+        const int reminder = itemsCount % rangeBlocksCount;
+        
+        // Reminder is distributed among first iterations
+        const int shift = std::min(rangeIteration, reminder);
+        const int reminded = (rangeIteration < reminder)?1:0;
+
+        rangeStart = rangeIteration * chunkSize + shift;
+        rangeEnd = rangeStart + chunkSize + reminded;
+    }
+
+    rangeEnd = std::min(rangeEnd, itemsCount);
+
+    return (rangeStart < itemsCount);
+}
+
+}  // namespace aliceVision

src/aliceVision/system/Parallelization.hpp

@@ -0,0 +1,23 @@
+// This file is part of the AliceVision project.
+// Copyright (c) 2025 AliceVision contributors.
+// This Source Code Form is subject to the terms of the Mozilla Public License,
+// v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#pragma once
+
+
+namespace aliceVision {
+
+/**
+ * Utility function to compute range of values to process
+ * Assuming we have itemsCount items in a container.
+ * @param[out] rangeStart is the first element index to process 
+ * @param[out] rangeEnd is the last element index to process (non included)
+ * @param rangeIteration is the iteration number
+ * @param rangeBlocksCount is the number of iterations launched in parallel
+ * @return false if nothing has to be processed in this iteration
+*/
+bool rangeComputation(int & rangeStart, int & rangeEnd, int rangeIteration, int rangeBlocksCount, int itemsCount);
+
+}  // namespace aliceVision

src/software/pipeline/main_relativePoseEstimating.cpp

@@ -10,6 +10,7 @@
 #include <aliceVision/system/Timer.hpp>
 #include <aliceVision/system/Logger.hpp>
 #include <aliceVision/system/main.hpp>
+#include <aliceVision/system/Parallelization.hpp>
 #include <aliceVision/cmdline/cmdline.hpp>
 
 #include <aliceVision/sfmData/SfMData.hpp>
@@ -140,8 +141,8 @@ int aliceVision_main(int argc, char** argv)
     std::string sfmDataFilename;
     std::string tracksFilename;
     std::string outputDirectory;
-    int rangeStart = -1;
-    int rangeSize = 1;
+    int rangeIteration = 0;
+    int rangeBlocksCount = 1;
     size_t minInliers = 35;
     bool enforcePureRotation = false;
     size_t countIterations = 1024;
@@ -166,8 +167,8 @@ int aliceVision_main(int argc, char** argv)
         ("minInliers", po::value<size_t>(&minInliers)->default_value(minInliers), "Minimal number of inliers for a valid ransac.")
         ("imagePairsList,l", po::value<std::vector<std::string>>(&predefinedPairList)->multitoken(),
          "Path(s) to one or more files which contain the list of image pairs to match.")
-        ("rangeStart", po::value<int>(&rangeStart)->default_value(rangeStart), "Range image index start.")
-        ("rangeSize", po::value<int>(&rangeSize)->default_value(rangeSize), "Range size.");
+        ("rangeIteration", po::value<int>(&rangeIteration)->default_value(rangeIteration), "Chunk id.")
+        ("rangeBlocksCount", po::value<int>(&rangeBlocksCount)->default_value(rangeBlocksCount), "Chunk count.");
     // clang-format on
 
     CmdLine cmdline("AliceVision relativePoseEstimating");
@@ -193,33 +194,6 @@ int aliceVision_main(int argc, char** argv)
         return EXIT_FAILURE;
     }
 
-    // Define range to compute
-    if(rangeStart != -1)
-    {
-        if(rangeStart < 0 || rangeSize < 0)
-        {
-            ALICEVISION_LOG_ERROR("Range is incorrect");
-            return EXIT_FAILURE;
-        }
-
-        if (rangeStart > sfmData.getViews().size())
-        {
-            ALICEVISION_LOG_INFO("Empty range to compute");
-            return EXIT_SUCCESS;
-        }
-
-        if(rangeStart + rangeSize > sfmData.getViews().size())
-        {
-            rangeSize = sfmData.getViews().size() - rangeStart;
-        }
-    }
-    else
-    {
-        rangeStart = 0;
-        rangeSize = sfmData.getViews().size();
-    }
-    ALICEVISION_LOG_DEBUG("Range to compute: rangeStart=" << rangeStart << ", rangeSize=" << rangeSize);
-
 
     // Load tracks
     ALICEVISION_LOG_INFO("Load tracks from " << tracksFilename << ".");
@@ -233,20 +207,14 @@ int aliceVision_main(int argc, char** argv)
     ALICEVISION_LOG_INFO("Compute co-visibility");
     std::map<Pair, unsigned int> covisibility;
 
-    int chunkStart = 0;
-    int chunkEnd = 0;
+    
 
     if (predefinedPairList.empty())
     {
         //Compute covisibility for tracks
         //This will get the list of pair of views which observe common features
         ALICEVISION_LOG_INFO("Automatically select pairs.");
         track::computeCovisibility(covisibility, tracksHandler.getAllTracks());
-        
-        //Divide the work among chunks
-        double ratioChunk = double(covisibility.size()) / double(sfmData.getViews().size());
-        chunkStart = int(double(rangeStart) * ratioChunk);
-        chunkEnd = int(double(rangeStart + rangeSize) * ratioChunk);
     }
     else
     {
@@ -256,7 +224,7 @@ int aliceVision_main(int argc, char** argv)
             PairSet pairs;
 
             ALICEVISION_LOG_INFO("Load pair list from file: " << imagePairsFile);
-            if (!matchingImageCollection::loadPairsFromFile(imagePairsFile, pairs, rangeStart, rangeSize))
+            if (!matchingImageCollection::loadPairsFromFile(imagePairsFile, pairs, 0, -1))
             {
                 return EXIT_FAILURE;
             }
@@ -273,10 +241,12 @@ int aliceVision_main(int argc, char** argv)
                 covisibility[other] = 1;
             }
         }
+    }
 
-        //Just process everything as it was already filtered during file loading
-        chunkStart = 0;
-        chunkEnd = covisibility.size();
+    int chunkStart, chunkEnd;
+    if (!rangeComputation(chunkStart, chunkEnd, rangeIteration, rangeBlocksCount, covisibility.size()))
+    {
+        ALICEVISION_LOG_INFO("Nothing to compute in this chunk");
     }
 
     ALICEVISION_LOG_INFO("A total of " << covisibility.size() << " pairs has to be processed.");
@@ -287,11 +257,11 @@ int aliceVision_main(int argc, char** argv)
 
     ALICEVISION_LOG_INFO("Process co-visibility");
     std::stringstream ss;
-    ss << outputDirectory << "/pairs_" << rangeStart << ".json";
+    ss << outputDirectory << "/pairs_" << rangeIteration << ".json";
     std::ofstream of(ss.str());
 
     // For each covisible pair
-#pragma omp parallel for
+#pragma omp parallel for schedule(dynamic)
     for (int posPairs = chunkStart; posPairs < chunkEnd; posPairs++)
     {
         auto iterPairs = covisibility.begin();
@@ -311,6 +281,11 @@ int aliceVision_main(int argc, char** argv)
         aliceVision::track::TracksMap mapTracksCommon;
         track::getCommonTracksInImagesFast({refImage, nextImage}, tracksHandler.getAllTracks(), tracksHandler.getTracksPerView(), mapTracksCommon);
 
+        if (mapTracksCommon.size() == 0)
+        {
+            continue;
+        }
+
         // Build features coordinates matrices
         const std::size_t n = mapTracksCommon.size();
         std::vector<Eigen::Vector2d> refpts, nextpts;