Reduce memory usage for large file uploads

benchmarks/local/sinatra/Gemfile

@@ -0,0 +1,13 @@
+source "http://rubygems.org"
+git_source(:github) { |repo| "https://github.com/#{repo}.git" }
+
+ruby "3.2.0"
+
+gem "sinatra"
+gem "puma_worker_killer"
+
+# current puma release
+gem "puma"
+
+# PR to reduce memory of large file uploads
+# gem "puma", github: "willkoehler/puma", branch: "reduce_read_body_memory"

benchmarks/local/sinatra/README.md

@@ -0,0 +1,92 @@
+# Large file upload demo
+
+This is a simple app to demonstrate memory used by Puma for large file uploads and
+compare it to proposed changes in PR https://github.com/puma/puma/pull/3062
+
+### Steps to test memory improvements in https://github.com/puma/puma/pull/3062
+
+- Run the app with puma_worker_killer: `bundle exec puma -p 9090 --config puma.rb`
+- Make a POST request with curl: `curl --form "data=@some_large_file.mp4" --limit-rate 10M http://localhost:9090/`
+- Puma will log memory usage in the console
+
+Below is example of the results uploading a 115MB video.
+
+### Puma 6.0.2
+
+```
+[11820] Puma starting in cluster mode...
+[11820] * Puma version: 6.0.2 (ruby 3.2.0-p0) ("Sunflower")
+[11820] *  Min threads: 0
+[11820] *  Max threads: 5
+[11820] *  Environment: development
+[11820] *   Master PID: 11820
+[11820] *      Workers: 1
+[11820] *     Restarts: (✔) hot (✔) phased
+[11820] * Listening on http://0.0.0.0:3000
+[11820] Use Ctrl-C to stop
+[11820] - Worker 0 (PID: 11949) booted in 0.06s, phase: 0
+[11820] PumaWorkerKiller: Consuming 70.984375 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 70.984375 mb with master and 1 workers.
+
+...curl request made - memory increases as file is received
+
+[11820] PumaWorkerKiller: Consuming 72.796875 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 75.921875 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 78.953125 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 82.15625 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 85.265625 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 88.046875 mb with master and 1 workers.
+
+...(clipped out lines) memory keeps increasing while request is received
+
+[11820] PumaWorkerKiller: Consuming 121.53125 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 122.75 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 125.40625 mb with master and 1 workers.
+
+...request handed off from Puma to Rack/Sinatra
+
+[11820] PumaWorkerKiller: Consuming 220.6875 mb with master and 1 workers.
+127.0.0.1 - - [26/Jan/2023:20:09:56 -0500] "POST /upload HTTP/1.1" 200 162 0.0553
+[11820] PumaWorkerKiller: Consuming 228.96875 mb with master and 1 workers.
+[11820] PumaWorkerKiller: Consuming 228.96875 mb with master and 1 workers.
+```
+
+### With PR https://github.com/puma/puma/pull/3062
+
+```
+[20815] Puma starting in cluster mode...
+[20815] * Puma version: 6.0.2 (ruby 3.2.0-p0) ("Sunflower")
+[20815] *  Min threads: 0
+[20815] *  Max threads: 5
+[20815] *  Environment: development
+[20815] *   Master PID: 20815
+[20815] *      Workers: 1
+[20815] *     Restarts: (✔) hot (✔) phased
+[20815] * Listening on http://0.0.0.0:3000
+[20815] Use Ctrl-C to stop
+[20815] - Worker 0 (PID: 20944) booted in 0.1s, phase: 0
+[20815] PumaWorkerKiller: Consuming 73.25 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.25 mb with master and 1 workers.
+
+...curl request made - memory stays level as file is received
+
+[20815] PumaWorkerKiller: Consuming 73.28125 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.296875 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.34375 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.359375 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.359375 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.359375 mb with master and 1 workers.
+
+...(clipped out lines) memory continues to stay level
+
+[20815] PumaWorkerKiller: Consuming 73.703125 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.703125 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 73.703125 mb with master and 1 workers.
+
+...request handed off from Puma to Rack/Sinatra
+
+[20815] PumaWorkerKiller: Consuming 181.96875 mb with master and 1 workers.
+127.0.0.1 - - [26/Jan/2023:20:27:16 -0500] "POST /upload HTTP/1.1" 200 162 0.0585
+[20815] PumaWorkerKiller: Consuming 183.78125 mb with master and 1 workers.
+[20815] PumaWorkerKiller: Consuming 183.78125 mb with master and 1 workers.
+```

benchmarks/local/sinatra/config.ru

@@ -0,0 +1,7 @@
+require "sinatra"
+
+post "/" do
+  204
+end
+
+run Sinatra::Application

benchmarks/local/sinatra/puma.rb

@@ -0,0 +1,15 @@
+silence_single_worker_warning
+
+workers 1
+
+before_fork do
+  require "puma_worker_killer"
+
+  PumaWorkerKiller.config do |config|
+    config.ram = 1024 # mb
+    config.frequency = 0.3 # seconds
+    config.reaper_status_logs = true # Log memory: PumaWorkerKiller: Consuming 54.34765625 mb with master and 1 workers.
+  end
+
+  PumaWorkerKiller.start
+end

lib/puma/client.rb

@@ -98,6 +98,8 @@ def initialize(io, env=nil)
       @body_remain = 0
 
       @in_last_chunk = false
+
+      @read_buffer = +""
     end
 
     attr_reader :env, :to_io, :body, :io, :timeout_at, :ready, :hijacked,
@@ -433,7 +435,7 @@ def read_body
       end
 
       begin
-        chunk = @io.read_nonblock(want)
+        chunk = @io.read_nonblock(want, @read_buffer)
       rescue IO::WaitReadable
         return false
       rescue SystemCallError, IOError
@@ -465,7 +467,7 @@ def read_body
     def read_chunked_body
       while true
         begin
-          chunk = @io.read_nonblock(4096)
+          chunk = @io.read_nonblock(4096, @read_buffer)
         rescue IO::WaitReadable
           return false
         rescue SystemCallError, IOError