SIGTT{IN,OU} {in,de}crements worker_processes

This allows dynamic tuning of the worker_processes count without
having to restart existing ones.  This also allows
worker_processes to be set to a low initial amount in the config
file for low-traffic deployments/upgrades and then scaled up as
the old processes are killed off.

Remove the proposed reexec_worker_processes from TODO since this
is far more flexible and powerful.

This will allow not-yet-existent third-party monitoring tools to
dynamically change and scale worker processes according to site
load without increasing the complexity of Unicorn itself.

1 files changed, 22 insertions, 0 deletions

diff --git a/test/exec/test_exec.rb b/test/exec/test_exec.rb
index b0462dc..014b270 100644
--- a/test/exec/test_exec.rb
+++ b/test/exec/test_exec.rb
@@ -98,6 +98,28 @@ end
     assert_shutdown(pid)
   end
 
+  def test_ttin_ttou
+    File.open("config.ru", "wb") { |fp| fp.syswrite(HI) }
+    pid = fork { redirect_test_io { exec($unicorn_bin, "-l#@addr:#@port") } }
+    log = "test_stderr.#{pid}.log"
+    wait_master_ready(log)
+    [ 2, 3].each { |i|
+      assert_nothing_raised { Process.kill(:TTIN, pid) }
+      wait_workers_ready(log, i)
+    }
+    File.truncate(log, 0)
+    reaped = nil
+    [ 2, 1, 0].each { |i|
+      assert_nothing_raised { Process.kill(:TTOU, pid) }
+      DEFAULT_TRIES.times {
+        sleep DEFAULT_RES
+        reaped = File.readlines(log).grep(/reaped.*\s*worker=#{i}$/)
+        break if reaped.size == 1
+      }
+      assert_equal 1, reaped.size
+    }
+  end
+
   def test_help
     redirect_test_io do
       assert(system($unicorn_bin, "-h"), "help text returns true")