[PATCH 1/3] test/benchmark/ddstream: demo for slowly reading clients

[Eric Wong <e@80x24.org>]

This is intended to demonstrate how badly we suck at dealing
with slow clients.  It can help users evaluate alternative
fully-buffering reverse proxies, because nginx should not
be the only option.

Update the benchmark README while we're at it
---
 test/benchmark/README      | 13 +++++++---
 test/benchmark/ddstream.ru | 50 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 4 deletions(-)
 create mode 100644 test/benchmark/ddstream.ru

diff --git a/test/benchmark/README b/test/benchmark/README
index 1d3cdd0..e9b7a41 100644
--- a/test/benchmark/README
+++ b/test/benchmark/README
@@ -42,9 +42,14 @@ The benchmark client is usually httperf.
 Another gentle reminder: performance with slow networks/clients
 is NOT our problem.  That is the job of nginx (or similar).
 
+== ddstream.ru
+
+Standalone Rack app intended to show how BAD we are at slow clients.
+See usage in comments.
+
 == Contributors
 
-This directory is maintained independently in the "benchmark" branch
-based against v0.1.0.  Only changes to this directory (test/benchmarks)
-are committed to this branch although the master branch may merge this
-branch occassionaly.
+This directory is intended to remain stable.  Do not make changes
+to benchmarking code which can change performance and invalidate
+results across revisions.  Instead, write new benchmarks and update
+coments/documentation as necessary.
diff --git a/test/benchmark/ddstream.ru b/test/benchmark/ddstream.ru
new file mode 100644
index 0000000..b14c973
--- /dev/null
+++ b/test/benchmark/ddstream.ru
@@ -0,0 +1,50 @@
+# This app is intended to test large HTTP responses with or without
+# a fully-buffering reverse proxy such as nginx. Without a fully-buffering
+# reverse proxy, unicorn will be unresponsive when client count exceeds
+# worker_processes.
+#
+# To demonstrate how bad unicorn is at slowly reading clients:
+#
+#   # in one terminal, start unicorn with one worker:
+#   unicorn -E none -l 127.0.0.1:8080 test/benchmark/ddstream.ru
+#
+#   # in a different terminal, start more slow curl processes than
+#   # unicorn workers and watch time outputs
+#   curl --limit-rate 8K --trace-time -vsN http://127.0.0.1:8080/ >/dev/null &
+#   curl --limit-rate 8K --trace-time -vsN http://127.0.0.1:8080/ >/dev/null &
+#   wait
+#
+# The last client won't see a response until the first one is done reading
+#
+# nginx note: do not change the default "proxy_buffering" behavior.
+# Setting "proxy_buffering off" prevents nginx from protecting unicorn.
+
+# totally standalone rack app to stream a giant response
+class BigResponse
+  def initialize(bs, count)
+    @buf = "#{bs.to_s(16)}\r\n#{' ' * bs}\r\n"
+    @count = count
+    @res = [ 200,
+      { 'Transfer-Encoding' => -'chunked', 'Content-Type' => 'text/plain' },
+      self
+    ]
+  end
+
+  # rack response body iterator
+  def each
+    (1..@count).each { yield @buf }
+    yield -"0\r\n\r\n"
+  end
+
+  # rack app entry endpoint
+  def call(_env)
+    @res
+  end
+end
+
+# default to a giant (128M) response because kernel socket buffers
+# can be ridiculously large on some systems
+bs = ENV['bs'] ? ENV['bs'].to_i : 65536
+count = ENV['count'] ? ENV['count'].to_i : 2048
+warn "serving response with bs=#{bs} count=#{count} (#{bs*count} bytes)"
+run BigResponse.new(bs, count)
-- 
EW