Merge pull request #12844 from apolcyn/backport_ruby_gc_rooted_bugs

Backport ruby non-GC-rooted variable fixes to 1.6.x
diff --git a/src/ruby/end2end/load_grpc_with_gc_stress_driver.rb b/src/ruby/end2end/load_grpc_with_gc_stress_driver.rb
new file mode 100755
index 0000000..3668b95
--- /dev/null
+++ b/src/ruby/end2end/load_grpc_with_gc_stress_driver.rb
@@ -0,0 +1,32 @@
+#!/usr/bin/env ruby
+#
+# Copyright 2016 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+this_dir = File.expand_path(File.dirname(__FILE__))
+protos_lib_dir = File.join(this_dir, 'lib')
+grpc_lib_dir = File.join(File.dirname(this_dir), 'lib')
+$LOAD_PATH.unshift(grpc_lib_dir) unless $LOAD_PATH.include?(grpc_lib_dir)
+$LOAD_PATH.unshift(protos_lib_dir) unless $LOAD_PATH.include?(protos_lib_dir)
+$LOAD_PATH.unshift(this_dir) unless $LOAD_PATH.include?(this_dir)
+
+GC.stress = 0x04
+
+require 'grpc'
+
+GRPC::Core::Channel.new('dummy_host', nil, :this_channel_is_insecure)
+GRPC::Core::Server.new({})
+GRPC::Core::ChannelCredentials.new
+GRPC::Core::CallCredentials.new(proc { |noop| noop })
+GRPC::Core::CompressionOptions.new
diff --git a/src/ruby/ext/grpc/rb_call.c b/src/ruby/ext/grpc/rb_call.c
index 58edf06..29c4a94 100644
--- a/src/ruby/ext/grpc/rb_call.c
+++ b/src/ruby/ext/grpc/rb_call.c
@@ -906,6 +906,9 @@
   rb_define_const(grpc_rb_mRpcErrors, "INVALID_FLAGS",
                   UINT2NUM(GRPC_CALL_ERROR_INVALID_FLAGS));
 
+  /* Hint the GC that this is a global and shouldn't be sweeped. */
+  rb_global_variable(&rb_error_code_details);
+
   /* Add the detail strings to a Hash */
   rb_error_code_details = rb_hash_new();
   rb_hash_aset(rb_error_code_details, UINT2NUM(GRPC_CALL_OK),
diff --git a/src/ruby/ext/grpc/rb_grpc.c b/src/ruby/ext/grpc/rb_grpc.c
index 933a3ac..b53f09e 100644
--- a/src/ruby/ext/grpc/rb_grpc.c
+++ b/src/ruby/ext/grpc/rb_grpc.c
@@ -315,8 +315,8 @@
     return;
   }
 
-  bg_thread_init_rb_mu = rb_mutex_new();
   rb_global_variable(&bg_thread_init_rb_mu);
+  bg_thread_init_rb_mu = rb_mutex_new();
 
   grpc_rb_mGRPC = rb_define_module("GRPC");
   grpc_rb_mGrpcCore = rb_define_module_under(grpc_rb_mGRPC, "Core");
diff --git a/tools/run_tests/helper_scripts/run_ruby_end2end_tests.sh b/tools/run_tests/helper_scripts/run_ruby_end2end_tests.sh
index 7914b0e..5cfab14 100755
--- a/tools/run_tests/helper_scripts/run_ruby_end2end_tests.sh
+++ b/tools/run_tests/helper_scripts/run_ruby_end2end_tests.sh
@@ -27,4 +27,5 @@
 ruby src/ruby/end2end/forking_client_driver.rb || EXIT_CODE=1
 ruby src/ruby/end2end/grpc_class_init_driver.rb || EXIT_CODE=1
 ruby src/ruby/end2end/multiple_killed_watching_threads_driver.rb || EXIT_CODE=1
+ruby src/ruby/end2end/load_grpc_with_gc_stress_driver.rb || EXIT_CODE=1
 exit $EXIT_CODE