cluster.rb - no zombies (#1887)

* cluster.rb - fixup for Cluster#check_workers, removes zombies?

* test_integration.rb - add zombie test

Co-authored-by: Matt Duszynski <mattduszynski@gmail.com>

* travis.yml - misc updates

jruby-head to bionic
xcode10.2 to xcode11
all ruby 2.2 to 2.2.10

.travis.yml

@@ -37,25 +37,27 @@ rvm:
 matrix:
   fast_finish: true
   include:
-    - rvm: 2.2 
-      dist: trusty 
+    - rvm: 2.2.10
+      dist: trusty
       env: OS="Trusty 14.04 OpenSSL 1.0.1"
-    - rvm: 2.6
+    - rvm: 2.6.3
       dist: bionic
       env: OS="Bionic 18.04 OpenSSL 1.1.1"
     - rvm: ruby-head
       env: jit=yes
     - rvm: 2.4.6
       os: osx
-      osx_image: xcode10.2
-      env: OS="osx xcode10.2"
+      osx_image: xcode11
+      env: OS="osx xcode11"
     - rvm: 2.5.5
       os: osx
-      osx_image: xcode10.2
-      env: OS="osx xcode10.2"
+      osx_image: xcode11
+      env: OS="osx xcode11"
     - rvm: jruby-9.2.7.0
       env: JRUBY_OPTS="--debug" JAVA_OPTS="--add-opens java.base/sun.nio.ch=org.jruby.dist --add-opens java.base/java.io=org.jruby.dist --add-opens java.base/java.util.zip=ALL-UNNAMED --add-opens java.base/java.util=ALL-UNNAMED --add-opens java.base/java.security.cert=ALL-UNNAMED --add-opens java.base/java.security=ALL-UNNAMED --add-opens java.base/java.io=ALL-UNNAMED"
     - rvm: jruby-head
+      dist: bionic
+      env: OS="Bionic 18.04"
 
   allow_failures:
     - rvm: ruby-head
@@ -63,6 +65,8 @@ matrix:
       env: jit=yes
     - rvm: jruby-9.2.7.0
     - rvm: jruby-head
+      dist: bionic
+      env: OS="Bionic 18.04"
 
 env:
   global:

lib/puma/cluster.rb

@@ -227,9 +227,11 @@ module Puma
       # during this loop by giving the kernel time to kill them.
       sleep 1 if any
 
-      @workers.reject! { |w| Process.waitpid(w.pid, Process::WNOHANG) }
-
-      @workers.reject!(&:dead?)
+      pids = []
+      while pid = Process.waitpid(-1, Process::WNOHANG) do
+        pids << pid
+      end
+      @workers.reject! { |w| w.dead? || pids.include?(w.pid) }
 
       cull_workers
       spawn_workers

test/test_integration.rb

@@ -374,4 +374,22 @@ class TestIntegration < Minitest::Test
     Process.wait(@server.pid)
     @server = nil # prevent `#teardown` from killing already killed server
   end
+
+  def test_no_zombie_children
+    skip NO_FORK_MSG unless HAS_FORK
+
+    worker_pids = []
+    server = server("-w 2 test/rackup/hello.ru")
+    # Get the PIDs of the child workers.
+    while worker_pids.size < 2
+      next unless line = server.gets.match(/pid: (\d+)/)
+      worker_pids << line.captures.first.to_i
+    end
+    # Signal the workers to terminate, and wait for them to die.
+    worker_pids.each { |pid| Process.kill :TERM, pid }
+    sleep 2
+
+    # Should return nil if Puma has correctly cleaned up
+    assert_nil Process.waitpid(-1, Process::WNOHANG)
+  end
 end