From af9eeffcf70d7795107c2b0511bdba507ac45339 Mon Sep 17 00:00:00 2001
From: generatedunixname1395027625275998 <noreply+1395027625275998@fb.com>
Date: Mon, 31 Aug 2026 12:19:45 -0700
Subject: [PATCH] Reserve cs vector capacity in hammings_knn_mc_impl to avoid
 reallocations (#5548)

Summary: Pull Request resolved: https://github.com/facebookresearch/faiss/pull/5548

Reviewed By: rjaber

Differential Revision: D118055043

fbshipit-source-id: 47f6ecdf6197610ccbcd60a466a3bfc77cfcc4e1
---
 faiss/utils/hamming_distance/hamming_impl.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/faiss/utils/hamming_distance/hamming_impl.h b/faiss/utils/hamming_distance/hamming_impl.h
index 41a285161..76d41e474 100644
--- a/faiss/utils/hamming_distance/hamming_impl.h
+++ b/faiss/utils/hamming_distance/hamming_impl.h
@@ -149,6 +149,7 @@ void hammings_knn_mc_impl(
     std::unique_ptr<int64_t[]> all_ids_per_dis(new int64_t[na * nBuckets * k]);
 
     std::vector<HCounterState<HammingComputer>> cs;
+    cs.reserve(na);
     for (size_t i = 0; i < na; ++i) {
         cs.push_back(
                 HCounterState<HammingComputer>(