From 389648f466840130e0bea1e9c5f7c0a221cdeca0 Mon Sep 17 00:00:00 2001
From: Maarten Pronk <git@evetion.nl>
Date: Mon, 27 Jul 2026 22:39:22 +0200
Subject: [PATCH 1/3] Fix allocations due to sizehint.

---
 src/wkb.jl       |  4 ++--
 test/runtests.jl | 11 +++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/wkb.jl b/src/wkb.jl
index 2b6dcd3..599a7ea 100644
--- a/src/wkb.jl
+++ b/src/wkb.jl
@@ -65,7 +65,7 @@ Push WKB to `data` for a Pointlike `type` of `geom`.
 function getwkb!(data::Vector{UInt8}, type::GI.PointTrait, geom, first::Bool)
     ncoord = GI.ncoord(type, geom)
     if first
-        sizehint!(data, 21)
+        isempty(data) && sizehint!(data, 21)
         push!(data, 0x01)  # endianness
         wkbtype = geometry_code(type)
         ncoord == 3 && (wkbtype |= wkbZ)
@@ -110,7 +110,7 @@ a geometrycollection.
 """
 function _getwkb!(data::Vector{UInt8}, type, geom, first::Bool, repeat::Bool)
     if first
-        sizehint!(data, 42)  # smallest non-point geometry is a line with 2 points
+        isempty(data) && sizehint!(data, 42)  # smallest non-point geometry is a line with 2 points
         push!(data, 0x01)  # endianness
         wkbtype = geometry_code(type)
         ncoord = GI.ncoord(type, geom)
diff --git a/test/runtests.jl b/test/runtests.jl
index 669e393..e2bdcc5 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -252,4 +252,15 @@ import LibGEOS
         wkbc = WKG.wkb"01010000000000000000003e400000000000002440"
         @test wkba == wkbb == wkbc
     end
+
+    @testset "Allocation" begin
+        ring(n) = GI.LinearRing([(Float64(i), Float64(i)) for i in 1:n])
+        mpoly(k) = GI.MultiPolygon([GI.Polygon([ring(100_000 ÷ k)]) for _ in 1:k])  # 100k vertices total
+
+        for k in (1, 25, 50, 100)
+            mp = mpoly(k)
+            a = @allocated WKG.getwkb(mp)
+            @test a == 6313136
+        end
+    end
 end

From d8ec4817f227f324a43b8ef49f7f398070532df0 Mon Sep 17 00:00:00 2001
From: Maarten Pronk <git@evetion.nl>
Date: Tue, 28 Jul 2026 09:08:39 +0200
Subject: [PATCH 2/3] Warmup.

---
 test/runtests.jl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/runtests.jl b/test/runtests.jl
index e2bdcc5..575b9cb 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -257,6 +257,7 @@ import LibGEOS
         ring(n) = GI.LinearRing([(Float64(i), Float64(i)) for i in 1:n])
         mpoly(k) = GI.MultiPolygon([GI.Polygon([ring(100_000 ÷ k)]) for _ in 1:k])  # 100k vertices total
 
+        WKG.getwkb(mpoly(1))  # warmup
         for k in (1, 25, 50, 100)
             mp = mpoly(k)
             a = @allocated WKG.getwkb(mp)

From ab02d31d556d7db4767913917cca27d6de896f46 Mon Sep 17 00:00:00 2001
From: Maarten Pronk <git@evetion.nl>
Date: Tue, 28 Jul 2026 11:43:37 +0200
Subject: [PATCH 3/3] Different way of testing allocs.

---
 test/runtests.jl | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/test/runtests.jl b/test/runtests.jl
index 575b9cb..47e5097 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -257,11 +257,13 @@ import LibGEOS
         ring(n) = GI.LinearRing([(Float64(i), Float64(i)) for i in 1:n])
         mpoly(k) = GI.MultiPolygon([GI.Polygon([ring(100_000 ÷ k)]) for _ in 1:k])  # 100k vertices total
 
-        WKG.getwkb(mpoly(1))  # warmup
+        mp = mpoly(1)
+        WKG.getwkb(mp)  # warmup
+        a = @allocated WKG.getwkb(mp)
         for k in (1, 25, 50, 100)
             mp = mpoly(k)
-            a = @allocated WKG.getwkb(mp)
-            @test a == 6313136
+            b = @allocated WKG.getwkb(mp)
+            @test a == b
         end
     end
 end