inspector: split the HostPort being used and the one parsed from CLI

Instead of using a shared pointer of the entire debug option set,
pass the parsed debug option to inspector classes by value because
they are set once the CLI argument parsing is done. Add another shared
pointer to HostPort being used by the inspector server, which is copied
from the one in the debug options initially. The port of the shared
HostPort is 9229 by default and can be specified as 0 initially but
will be set to the actual port of the server once it starts listening.

This makes the shared state clearer and makes it possible to use
`require('internal/options')` in JS land to query the CLI options
instead of using `process._breakFirstLine` and other underscored
properties of `process` since we are now certain that these
values should not be altered once the parsing is done and can be
passed around in copies without locks.

PR-URL: https://github.com/nodejs/node/pull/24772
Reviewed-By: Anna Henningsen <anna@addaleax.net>

15 files changed, 160 insertions, 98 deletions

diff --git a/src/env-inl.h b/src/env-inl.h
index ba5704ed2e..f28701c70f 100644
--- a/src/env-inl.h
+++ b/src/env-inl.h
@@ -585,6 +585,10 @@ inline std::shared_ptr<EnvironmentOptions> Environment::options() {
   return options_;
 }
 
+inline std::shared_ptr<HostPort> Environment::inspector_host_port() {
+  return inspector_host_port_;
+}
+
 inline std::shared_ptr<PerIsolateOptions> IsolateData::options() {
   return options_;
 }
diff --git a/src/env.cc b/src/env.cc
index bdb3c1ea24..6d69339b58 100644
--- a/src/env.cc
+++ b/src/env.cc
@@ -5,6 +5,7 @@
 #include "node_file.h"
 #include "node_internals.h"
 #include "node_native_module.h"
+#include "node_options-inl.h"
 #include "node_platform.h"
 #include "node_worker.h"
 #include "tracing/agent.h"
@@ -192,7 +193,7 @@ Environment::Environment(IsolateData* isolate_data,
   // part of the per-Isolate option set, for which in turn the defaults are
   // part of the per-process option set.
   options_.reset(new EnvironmentOptions(*isolate_data->options()->per_env));
-  options_->debug_options.reset(new DebugOptions(*options_->debug_options));
+  inspector_host_port_.reset(new HostPort(options_->debug_options().host_port));
 
 #if HAVE_INSPECTOR
   // We can only create the inspector agent after having cloned the options.
diff --git a/src/env.h b/src/env.h
index 64593a0025..ec0368e040 100644
--- a/src/env.h
+++ b/src/env.h
@@ -911,6 +911,7 @@ class Environment {
                                  void* data);
 
   inline std::shared_ptr<EnvironmentOptions> options();
+  inline std::shared_ptr<HostPort> inspector_host_port();
 
  private:
   inline void CreateImmediate(native_immediate_callback cb,
@@ -942,6 +943,14 @@ class Environment {
   std::vector<double> destroy_async_id_list_;
 
   std::shared_ptr<EnvironmentOptions> options_;
+  // options_ contains debug options parsed from CLI arguments,
+  // while inspector_host_port_ stores the actual inspector host
+  // and port being used. For example the port is -1 by default
+  // and can be specified as 0 (meaning any port allocated when the
+  // server starts listening), but when the inspector server starts
+  // the inspector_host_port_->port() will be the actual port being
+  // used.
+  std::shared_ptr<HostPort> inspector_host_port_;
 
   uint32_t module_id_counter_ = 0;
   uint32_t script_id_counter_ = 0;
diff --git a/src/inspector_agent.cc b/src/inspector_agent.cc
index 21319abca7..8949dfe2a7 100644
--- a/src/inspector_agent.cc
+++ b/src/inspector_agent.cc
@@ -669,8 +669,9 @@ class NodeInspectorClient : public V8InspectorClient {
 };
 
 Agent::Agent(Environment* env)
-  : parent_env_(env),
-    debug_options_(env->options()->debug_options) {}
+    : parent_env_(env),
+      debug_options_(env->options()->debug_options()),
+      host_port_(env->inspector_host_port()) {}
 
 Agent::~Agent() {
   if (start_io_thread_async.data == this) {
@@ -681,13 +682,14 @@ Agent::~Agent() {
 }
 
 bool Agent::Start(const std::string& path,
-                  std::shared_ptr<DebugOptions> options,
+                  const DebugOptions& options,
+                  std::shared_ptr<HostPort> host_port,
                   bool is_main) {
-  if (options == nullptr) {
-    options = std::make_shared<DebugOptions>();
-  }
   path_ = path;
   debug_options_ = options;
+  CHECK_NE(host_port, nullptr);
+  host_port_ = host_port;
+
   client_ = std::make_shared<NodeInspectorClient>(parent_env_, is_main);
   if (parent_env_->is_main_thread()) {
     CHECK_EQ(0, uv_async_init(parent_env_->event_loop(),
@@ -699,13 +701,18 @@ bool Agent::Start(const std::string& path,
     StartDebugSignalHandler();
   }
 
-  bool wait_for_connect = options->wait_for_connect();
+  bool wait_for_connect = options.wait_for_connect();
   if (parent_handle_) {
     wait_for_connect = parent_handle_->WaitForConnect();
     parent_handle_->WorkerStarted(client_->getThreadHandle(), wait_for_connect);
-  } else if (!options->inspector_enabled || !StartIoThread()) {
+  } else if (!options.inspector_enabled || !StartIoThread()) {
     return false;
   }
+
+  // TODO(joyeecheung): we should not be using process as a global object
+  // to transport --inspect-brk. Instead, the JS land can get this through
+  // require('internal/options') since it should be set once CLI parsing
+  // is done.
   if (wait_for_connect) {
     HandleScope scope(parent_env_->isolate());
     parent_env_->process_object()->DefineOwnProperty(
@@ -725,8 +732,7 @@ bool Agent::StartIoThread() {
 
   CHECK_NOT_NULL(client_);
 
-  io_ = InspectorIo::Start(
-      client_->getThreadHandle(), path_, debug_options_);
+  io_ = InspectorIo::Start(client_->getThreadHandle(), path_, host_port_);
   if (io_ == nullptr) {
     return false;
   }
@@ -867,8 +873,7 @@ void Agent::ContextCreated(Local<Context> context, const ContextInfo& info) {
 }
 
 bool Agent::WillWaitForConnect() {
-  if (debug_options_->wait_for_connect())
-    return true;
+  if (debug_options_.wait_for_connect()) return true;
   if (parent_handle_)
     return parent_handle_->WaitForConnect();
   return false;
diff --git a/src/inspector_agent.h b/src/inspector_agent.h
index 9537ae05b6..5e599a6339 100644
--- a/src/inspector_agent.h
+++ b/src/inspector_agent.h
@@ -11,7 +11,7 @@
 #error("This header can only be used when inspector is enabled")
 #endif
 
-#include "node_options.h"
+#include "node_options-inl.h"
 #include "node_persistent.h"
 #include "v8.h"
 
@@ -50,8 +50,9 @@ class Agent {
 
   // Create client_, may create io_ if option enabled
   bool Start(const std::string& path,
-             std::shared_ptr<DebugOptions> options,
-             bool is_worker);
+             const DebugOptions& options,
+             std::shared_ptr<HostPort> host_port,
+             bool is_main);
   // Stop and destroy io_
   void Stop();
 
@@ -104,7 +105,8 @@ class Agent {
   // Calls StartIoThread() from off the main thread.
   void RequestIoThreadStart();
 
-  std::shared_ptr<DebugOptions> options() { return debug_options_; }
+  const DebugOptions& options() { return debug_options_; }
+  std::shared_ptr<HostPort> host_port() { return host_port_; }
   void ContextCreated(v8::Local<v8::Context> context, const ContextInfo& info);
 
   // Interface for interacting with inspectors in worker threads
@@ -121,7 +123,13 @@ class Agent {
   std::unique_ptr<InspectorIo> io_;
   std::unique_ptr<ParentInspectorHandle> parent_handle_;
   std::string path_;
-  std::shared_ptr<DebugOptions> debug_options_;
+
+  // This is a copy of the debug options parsed from CLI in the Environment.
+  // Do not use the host_port in that, instead manipulate the shared host_port_
+  // pointer which is meant to store the actual host and port of the inspector
+  // server.
+  DebugOptions debug_options_;
+  std::shared_ptr<HostPort> host_port_;
 
   bool pending_enable_async_hook_ = false;
   bool pending_disable_async_hook_ = false;
diff --git a/src/inspector_io.cc b/src/inspector_io.cc
index da44d55d06..7686294b2e 100644
--- a/src/inspector_io.cc
+++ b/src/inspector_io.cc
@@ -242,9 +242,9 @@ class InspectorIoDelegate: public node::inspector::SocketServerDelegate {
 std::unique_ptr<InspectorIo> InspectorIo::Start(
     std::shared_ptr<MainThreadHandle> main_thread,
     const std::string& path,
-    std::shared_ptr<DebugOptions> options) {
+    std::shared_ptr<HostPort> host_port) {
   auto io = std::unique_ptr<InspectorIo>(
-      new InspectorIo(main_thread, path, options));
+      new InspectorIo(main_thread, path, host_port));
   if (io->request_queue_->Expired()) {  // Thread is not running
     return nullptr;
   }
@@ -253,9 +253,12 @@ std::unique_ptr<InspectorIo> InspectorIo::Start(
 
 InspectorIo::InspectorIo(std::shared_ptr<MainThreadHandle> main_thread,
                          const std::string& path,
-                         std::shared_ptr<DebugOptions> options)
-                         : main_thread_(main_thread), options_(options),
-                           thread_(), script_name_(path), id_(GenerateID()) {
+                         std::shared_ptr<HostPort> host_port)
+    : main_thread_(main_thread),
+      host_port_(host_port),
+      thread_(),
+      script_name_(path),
+      id_(GenerateID()) {
   Mutex::ScopedLock scoped_lock(thread_start_lock_);
   CHECK_EQ(uv_thread_create(&thread_, InspectorIo::ThreadMain, this), 0);
   thread_start_condition_.Wait(scoped_lock);
@@ -287,16 +290,17 @@ void InspectorIo::ThreadMain() {
   std::unique_ptr<InspectorIoDelegate> delegate(
       new InspectorIoDelegate(queue, main_thread_, id_,
                               script_path, script_name_));
-  InspectorSocketServer server(std::move(delegate), &loop,
-                               options_->host().c_str(),
-                               options_->port());
+  InspectorSocketServer server(std::move(delegate),
+                               &loop,
+                               host_port_->host().c_str(),
+                               host_port_->port());
   request_queue_ = queue->handle();
   // Its lifetime is now that of the server delegate
   queue.reset();
   {
     Mutex::ScopedLock scoped_lock(thread_start_lock_);
     if (server.Start()) {
-      port_ = server.Port();
+      host_port_->set_port(server.Port());
     }
     thread_start_condition_.Broadcast(scoped_lock);
   }
diff --git a/src/inspector_io.h b/src/inspector_io.h
index 21df54e031..bc09afdd3d 100644
--- a/src/inspector_io.h
+++ b/src/inspector_io.h
@@ -46,21 +46,22 @@ class InspectorIo {
   // bool Start();
   // Returns empty pointer if thread was not started
   static std::unique_ptr<InspectorIo> Start(
-      std::shared_ptr<MainThreadHandle> main_thread, const std::string& path,
-      std::shared_ptr<DebugOptions> options);
+      std::shared_ptr<MainThreadHandle> main_thread,
+      const std::string& path,
+      std::shared_ptr<HostPort> host_port);
 
   // Will block till the transport thread shuts down
   ~InspectorIo();
 
   void StopAcceptingNewConnections();
-  const std::string& host() const { return options_->host(); }
-  int port() const { return port_; }
+  const std::string& host() const { return host_port_->host(); }
+  int port() const { return host_port_->port(); }
   std::vector<std::string> GetTargetIds() const;
 
  private:
   InspectorIo(std::shared_ptr<MainThreadHandle> handle,
               const std::string& path,
-              std::shared_ptr<DebugOptions> options);
+              std::shared_ptr<HostPort> host_port);
 
   // Wrapper for agent->ThreadMain()
   static void ThreadMain(void* agent);
@@ -74,7 +75,7 @@ class InspectorIo {
   // Used to post on a frontend interface thread, lives while the server is
   // running
   std::shared_ptr<RequestQueue> request_queue_;
-  std::shared_ptr<DebugOptions> options_;
+  std::shared_ptr<HostPort> host_port_;
 
   // The IO thread runs its own uv_loop to implement the TCP server off
   // the main thread.
@@ -84,7 +85,6 @@ class InspectorIo {
   Mutex thread_start_lock_;
   ConditionVariable thread_start_condition_;
   std::string script_name_;
-  int port_ = -1;
   // May be accessed from any thread
   const std::string id_;
 };
diff --git a/src/inspector_js_api.cc b/src/inspector_js_api.cc
index 52f14639a4..1cb51b51ec 100644
--- a/src/inspector_js_api.cc
+++ b/src/inspector_js_api.cc
@@ -243,12 +243,12 @@ void Open(const FunctionCallbackInfo<Value>& args) {
 
   if (args.Length() > 0 && args[0]->IsUint32()) {
     uint32_t port = args[0].As<Uint32>()->Value();
-    agent->options()->host_port.port = port;
+    agent->host_port()->set_port(static_cast<int>(port));
   }
 
   if (args.Length() > 1 && args[1]->IsString()) {
     Utf8Value host(env->isolate(), args[1].As<String>());
-    agent->options()->host_port.host_name = *host;
+    agent->host_port()->set_host(*host);
   }
 
   if (args.Length() > 2 && args[2]->IsBoolean()) {
diff --git a/src/node.cc b/src/node.cc
index ad0afd437d..f24ba12a81 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -27,6 +27,7 @@
 #include "node_internals.h"
 #include "node_metadata.h"
 #include "node_native_module.h"
+#include "node_options-inl.h"
 #include "node_perf.h"
 #include "node_platform.h"
 #include "node_revert.h"
@@ -257,13 +258,15 @@ static struct {
   }
 
 #if HAVE_INSPECTOR
-  bool StartInspector(Environment* env, const char* script_path,
-                      std::shared_ptr<DebugOptions> options) {
+  bool StartInspector(Environment* env, const char* script_path) {
     // Inspector agent can't fail to start, but if it was configured to listen
     // right away on the websocket port and fails to bind/etc, this will return
     // false.
     return env->inspector_agent()->Start(
-        script_path == nullptr ? "" : script_path, options, true);
+        script_path == nullptr ? "" : script_path,
+        env->options()->debug_options(),
+        env->inspector_host_port(),
+        true);
   }
 
   bool InspectorStarted(Environment* env) {
@@ -304,8 +307,7 @@ static struct {
   void Dispose() {}
   void DrainVMTasks(Isolate* isolate) {}
   void CancelVMTasks(Isolate* isolate) {}
-  bool StartInspector(Environment* env, const char* script_path,
-                      const DebugOptions& options) {
+  bool StartInspector(Environment* env, const char* script_path) {
     env->ThrowError("Node compiled with NODE_USE_V8_PLATFORM=0");
     return true;
   }
@@ -1090,24 +1092,24 @@ void SetupProcessObject(Environment* env,
 
   // TODO(refack): move the following 4 to `node_config`
   // --inspect-brk
-  if (env->options()->debug_options->wait_for_connect()) {
+  if (env->options()->debug_options().wait_for_connect()) {
     READONLY_DONT_ENUM_PROPERTY(process,
                                 "_breakFirstLine", True(env->isolate()));
   }
 
-  if (env->options()->debug_options->break_node_first_line) {
+  if (env->options()->debug_options().break_node_first_line) {
     READONLY_DONT_ENUM_PROPERTY(process,
                                 "_breakNodeFirstLine", True(env->isolate()));
   }
 
   // --inspect --debug-brk
-  if (env->options()->debug_options->deprecated_invocation()) {
+  if (env->options()->debug_options().deprecated_invocation()) {
     READONLY_DONT_ENUM_PROPERTY(process,
                                 "_deprecatedDebugBrk", True(env->isolate()));
   }
 
   // --debug or, --debug-brk without --inspect
-  if (env->options()->debug_options->invalid_invocation()) {
+  if (env->options()->debug_options().invalid_invocation()) {
     READONLY_DONT_ENUM_PROPERTY(process,
                                 "_invalidDebug", True(env->isolate()));
   }
@@ -1255,7 +1257,7 @@ void LoadEnvironment(Environment* env) {
           ->GetFunction(context)
           .ToLocalChecked(),
       Boolean::New(isolate,
-                   env->options()->debug_options->break_node_first_line)};
+                   env->options()->debug_options().break_node_first_line)};
 
   MaybeLocal<Value> loader_exports;
   // Bootstrap internal loaders
@@ -1290,12 +1292,10 @@ void LoadEnvironment(Environment* env) {
   }
 }
 
-
-static void StartInspector(Environment* env, const char* path,
-                           std::shared_ptr<DebugOptions> debug_options) {
+static void StartInspector(Environment* env, const char* path) {
 #if HAVE_INSPECTOR
   CHECK(!env->inspector_agent()->IsListening());
-  v8_platform.StartInspector(env, path, debug_options);
+  v8_platform.StartInspector(env, path);
 #endif  // HAVE_INSPECTOR
 }
 
@@ -1938,9 +1938,9 @@ inline int Start(Isolate* isolate, IsolateData* isolate_data,
   env.Start(args, exec_args, v8_is_profiling);
 
   const char* path = args.size() > 1 ? args[1].c_str() : nullptr;
-  StartInspector(&env, path, env.options()->debug_options);
+  StartInspector(&env, path);
 
-  if (env.options()->debug_options->inspector_enabled &&
+  if (env.options()->debug_options().inspector_enabled &&
       !v8_platform.InspectorStarted(&env)) {
     return 12;  // Signal internal error.
   }
diff --git a/src/node_config.cc b/src/node_config.cc
index c2bf3349c4..27ec44b8d3 100644
--- a/src/node_config.cc
+++ b/src/node_config.cc
@@ -1,5 +1,6 @@
 #include "node.h"
 #include "node_i18n.h"
+#include "node_options-inl.h"
 #include "env-inl.h"
 #include "util-inl.h"
 
@@ -94,20 +95,18 @@ static void Initialize(Local<Object> target,
     READONLY_STRING_PROPERTY(target, "warningFile", warning_file);
   }
 
-  std::shared_ptr<DebugOptions> debug_options = env->options()->debug_options;
   Local<Object> debug_options_obj = Object::New(isolate);
   READONLY_PROPERTY(target, "debugOptions", debug_options_obj);
 
-  READONLY_STRING_PROPERTY(debug_options_obj, "host",
-                           debug_options->host());
-
-  READONLY_PROPERTY(debug_options_obj,
-                    "port",
-                    Integer::New(isolate, debug_options->port()));
-
+  const DebugOptions& debug_options = env->options()->debug_options();
   READONLY_PROPERTY(debug_options_obj,
                     "inspectorEnabled",
-                    Boolean::New(isolate, debug_options->inspector_enabled));
+                    Boolean::New(isolate, debug_options.inspector_enabled));
+  READONLY_STRING_PROPERTY(
+      debug_options_obj, "host", debug_options.host_port.host());
+  READONLY_PROPERTY(debug_options_obj,
+                    "port",
+                    Integer::New(isolate, debug_options.host_port.port()));
 }  // InitConfig
 
 }  // namespace node
diff --git a/src/node_options-inl.h b/src/node_options-inl.h
index 468368ac84..8aaa62524b 100644
--- a/src/node_options-inl.h
+++ b/src/node_options-inl.h
@@ -14,7 +14,11 @@ PerIsolateOptions* PerProcessOptions::get_per_isolate_options() {
 }
 
 DebugOptions* EnvironmentOptions::get_debug_options() {
-  return debug_options.get();
+  return &debug_options_;
+}
+
+const DebugOptions& EnvironmentOptions::debug_options() const {
+  return debug_options_;
 }
 
 EnvironmentOptions* PerIsolateOptions::get_per_env_options() {
diff --git a/src/node_options.cc b/src/node_options.cc
index 885501839c..3f9e066f28 100644
--- a/src/node_options.cc
+++ b/src/node_options.cc
@@ -44,7 +44,9 @@ void EnvironmentOptions::CheckOptions(std::vector<std::string>* errors) {
     errors->push_back("invalid value for --http-parser");
   }
 
-  debug_options->CheckOptions(errors);
+#if HAVE_INSPECTOR
+  debug_options_.CheckOptions(errors);
+#endif  // HAVE_INSPECTOR
 }
 
 namespace options_parser {
@@ -54,7 +56,6 @@ namespace options_parser {
 // TODO(addaleax): Make that unnecessary.
 
 DebugOptionsParser::DebugOptionsParser() {
-#if HAVE_INSPECTOR
   AddOption("--inspect-port",
             "set host:port for inspector",
             &DebugOptions::host_port,
@@ -84,10 +85,11 @@ DebugOptionsParser::DebugOptionsParser() {
   AddOption("--debug-brk", "", &DebugOptions::break_first_line);
   Implies("--debug-brk", "--debug");
   AddAlias("--debug-brk=", { "--inspect-port", "--debug-brk" });
-#endif
 }
 
+#if HAVE_INSPECTOR
 DebugOptionsParser DebugOptionsParser::instance;
+#endif  // HAVE_INSPECTOR
 
 EnvironmentOptionsParser::EnvironmentOptionsParser() {
   AddOption("--experimental-modules",
@@ -214,8 +216,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             kAllowedInEnvironment);
 #endif
 
+#if HAVE_INSPECTOR
   Insert(&DebugOptionsParser::instance,
          &EnvironmentOptions::get_debug_options);
+#endif  // HAVE_INSPECTOR
 }
 
 EnvironmentOptionsParser EnvironmentOptionsParser::instance;
@@ -372,7 +376,7 @@ HostPort SplitHostPort(const std::string& arg,
   // so if it has an effect only an IPv6 address was specified.
   std::string host = RemoveBrackets(arg);
   if (host.length() < arg.length())
-    return HostPort { host, -1 };
+    return HostPort{host, DebugOptions::kDefaultInspectorPort};
 
   size_t colon = arg.rfind(':');
   if (colon == std::string::npos) {
@@ -380,7 +384,7 @@ HostPort SplitHostPort(const std::string& arg,
     // if it's not all decimal digits, it's a host name.
     for (char c : arg) {
       if (c < '0' || c > '9') {
-        return HostPort { arg, -1 };
+        return HostPort{arg, DebugOptions::kDefaultInspectorPort};
       }
     }
     return HostPort { "", ParseAndValidatePort(arg, errors) };
@@ -446,11 +450,11 @@ void GetOptions(const FunctionCallbackInfo<Value>& args) {
         const HostPort& host_port = *parser.Lookup<HostPort>(field, opts);
         Local<Object> obj = Object::New(isolate);
         Local<Value> host;
-        if (!ToV8Value(context, host_port.host_name).ToLocal(&host) ||
+        if (!ToV8Value(context, host_port.host()).ToLocal(&host) ||
             obj->Set(context, env->host_string(), host).IsNothing() ||
             obj->Set(context,
                      env->port_string(),
-                     Integer::New(isolate, host_port.port))
+                     Integer::New(isolate, host_port.port()))
                 .IsNothing()) {
           return;
         }
diff --git a/src/node_options.h b/src/node_options.h
index dfe7ff6c5e..17dc708463 100644
--- a/src/node_options.h
+++ b/src/node_options.h
@@ -3,22 +3,44 @@
 
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
+#include <memory>
 #include <string>
-#include <vector>
 #include <unordered_map>
-#include <memory>
+#include <vector>
 #include "node_constants.h"
+#include "util.h"
 
 namespace node {
 
-struct HostPort {
-  std::string host_name;
-  int port;
+class HostPort {
+ public:
+  HostPort(const std::string& host_name, int port)
+      : host_name_(host_name), port_(port) {}
+  HostPort(const HostPort&) = default;
+  HostPort& operator=(const HostPort&) = default;
+  HostPort(HostPort&&) = default;
+  HostPort& operator=(HostPort&&) = default;
+
+  void set_host(const std::string& host) { host_name_ = host; }
+
+  void set_port(int port) { port_ = port; }
+
+  const std::string& host() const { return host_name_; }
+
+  int port() const {
+    // TODO(joyeecheung): make port a uint16_t
+    CHECK_GE(port_, 0);
+    return port_;
+  }
 
   void Update(const HostPort& other) {
-    if (!other.host_name.empty()) host_name = other.host_name;
-    if (other.port >= 0) port = other.port;
+    if (!other.host_name_.empty()) host_name_ = other.host_name_;
+    if (other.port_ >= 0) port_ = other.port_;
   }
+
+ private:
+  std::string host_name_;
+  int port_;
 };
 
 class Options {
@@ -33,13 +55,25 @@ class Options {
 // per-Isolate, rather than per-Environment.
 class DebugOptions : public Options {
  public:
+  DebugOptions() = default;
+  DebugOptions(const DebugOptions&) = default;
+  DebugOptions& operator=(const DebugOptions&) = default;
+  DebugOptions(DebugOptions&&) = default;
+  DebugOptions& operator=(DebugOptions&&) = default;
+
+  // --inspect
   bool inspector_enabled = false;
+  // --debug
   bool deprecated_debug = false;
+  // --inspect-brk
   bool break_first_line = false;
+  // --inspect-brk-node
   bool break_node_first_line = false;
-  HostPort host_port = {"127.0.0.1", -1};
+
   enum { kDefaultInspectorPort = 9229 };
 
+  HostPort host_port{"127.0.0.1", kDefaultInspectorPort};
+
   bool deprecated_invocation() const {
     return deprecated_debug &&
       inspector_enabled &&
@@ -53,19 +87,10 @@ class DebugOptions : public Options {
   bool wait_for_connect() const {
     return break_first_line || break_node_first_line;
   }
-
-  const std::string& host() {
-    return host_port.host_name;
-  }
-
-  int port() {
-    return host_port.port < 0 ? kDefaultInspectorPort : host_port.port;
-  }
 };
 
 class EnvironmentOptions : public Options {
  public:
-  std::shared_ptr<DebugOptions> debug_options { new DebugOptions() };
   bool abort_on_uncaught_exception = false;
   bool experimental_modules = false;
   bool experimental_repl_await = false;
@@ -108,7 +133,11 @@ class EnvironmentOptions : public Options {
   std::vector<std::string> user_argv;
 
   inline DebugOptions* get_debug_options();
+  inline const DebugOptions& debug_options() const;
   void CheckOptions(std::vector<std::string>* errors);
+
+ private:
+  DebugOptions debug_options_;
 };
 
 class PerIsolateOptions : public Options {
diff --git a/src/node_process.cc b/src/node_process.cc
index a3ccc2343e..792cc51092 100644
--- a/src/node_process.cc
+++ b/src/node_process.cc
@@ -825,14 +825,7 @@ void GetActiveHandles(const FunctionCallbackInfo<Value>& args) {
 void DebugPortGetter(Local<Name> property,
                      const PropertyCallbackInfo<Value>& info) {
   Environment* env = Environment::GetCurrent(info);
-  Mutex::ScopedLock lock(process_mutex);
-  int port = env->options()->debug_options->port();
-#if HAVE_INSPECTOR
-  if (port == 0) {
-    if (auto io = env->inspector_agent()->io())
-      port = io->port();
-  }
-#endif  // HAVE_INSPECTOR
+  int port = env->inspector_host_port()->port();
   info.GetReturnValue().Set(port);
 }
 
@@ -841,9 +834,8 @@ void DebugPortSetter(Local<Name> property,
                      Local<Value> value,
                      const PropertyCallbackInfo<void>& info) {
   Environment* env = Environment::GetCurrent(info);
-  Mutex::ScopedLock lock(process_mutex);
-  env->options()->debug_options->host_port.port =
-      value->Int32Value(env->context()).FromMaybe(0);
+  int32_t port = value->Int32Value(env->context()).FromMaybe(0);
+  env->inspector_host_port()->set_port(static_cast<int>(port));
 }
 
 
diff --git a/src/node_worker.cc b/src/node_worker.cc
index e99ac59c01..65d3b7297c 100644
--- a/src/node_worker.cc
+++ b/src/node_worker.cc
@@ -37,7 +37,10 @@ Mutex next_thread_id_mutex;
 
 #if NODE_USE_V8_PLATFORM && HAVE_INSPECTOR
 void StartWorkerInspector(Environment* child, const std::string& url) {
-  child->inspector_agent()->Start(url, nullptr, false);
+  child->inspector_agent()->Start(url,
+                                  child->options()->debug_options(),
+                                  child->inspector_host_port(),
+                                  false);
 }
 
 void AddWorkerInspector(Environment* parent,