From cdb404296169c6679825f6d6032d5ad2ca7eb8bd Mon Sep 17 00:00:00 2001
From: Martin Edenhofer <me@znuny.com>
Date: Tue, 5 Mar 2019 03:52:54 +0100
Subject: [PATCH] Fixes issue ##2504 - Login into Zammad not possible,
 application server `puma` will raise 100% or more cpu.

---
 app/models/store.rb | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/app/models/store.rb b/app/models/store.rb
index 52ed5292e..d6b7ca6fe 100644
--- a/app/models/store.rb
+++ b/app/models/store.rb
@@ -281,6 +281,10 @@ returns
     file.provider
   end
 
+  def self.semaphore
+    @semaphore ||= Mutex.new
+  end
+
   private
 
   def image_resize(content, width)
@@ -295,19 +299,25 @@ returns
     temp_file.binmode
     temp_file.write(content)
     temp_file.close
-    image = Rszr::Image.load(temp_file.path)
 
-    # do not resize image if image is smaller or already same size
-    return if image.width <= width
+    temp_file_resize = nil
+    self.class.semaphore.synchronize do
+      image = Rszr::Image.load(temp_file.path)
 
-    # do not resize image if new height is smaller then 7px (images
-    # with small height are usally usefull to resize)
-    ratio = image.width / width
-    return if image.height / ratio <= 6
+      # do not resize image if image is smaller or already same size
+      return if image.width <= width
+
+      # do not resize image if new height is smaller then 7px (images
+      # with small height are usally usefull to resize)
+      ratio = image.width / width
+      return if image.height / ratio <= 6
+
+      image.resize!(width, :auto)
+      temp_file_resize = ::Tempfile.new.path
+      image.save(temp_file_resize)
+      image.send(:handle).finalize!
+    end
 
-    image.resize!(width, :auto)
-    temp_file_resize = ::Tempfile.new.path
-    image.save(temp_file_resize)
     image_resized = ::File.binread(temp_file_resize)
 
     Cache.write(cache_key, image_resized, { expires_in: 6.months })