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inspector: implement --cpu-prof[-path]

This patch introduces a CLI flag --cpu-prof that starts the V8
CPU profiler on start up, and ends the profiler then writes the
CPU profile before the Node.js instance (on the main thread or
the worker thread) exits. By default the profile is written to
`${cwd}/CPU.${yyyymmdd}.${hhmmss}.${pid}.${tid}.${seq}.cpuprofile`.
The patch also introduces a --cpu-prof-path flag for the user
to specify the path the profile will be written to.

Refs: #26878
PR-URL: #27147
Reviewed-By: Anna Henningsen <anna@addaleax.net>
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joyeecheung committed Mar 22, 2019
1 parent 57ab3b5 commit e0e308448240260c207958dfc3dd9245d903af85
@@ -75,6 +75,37 @@ $ node --completion-bash > node_bash_completion
$ source node_bash_completion
```

### `--cpu-prof`
<!-- YAML
added: REPLACEME
-->

> Stability: 1 - Experimental
Starts the V8 CPU profiler on start up, and writes the CPU profile to disk
before exit. If `--cpu-prof-path` is not specified, the profile will be
written to `${cwd}/CPU.${yyyymmdd}.${hhmmss}.${pid}.${tid}.${seq}.cpuprofile`.

```console
$ node --cpu-prof index.js
$ ls *.cpuprofile
CPU.20190409.202950.15293.0.0.cpuprofile
```

### `--cpu-prof-path`
<!-- YAML
added: REPLACEME
-->

> Stability: 1 - Experimental
Location where the CPU profile generated by `--cpu-prof`
should be written to. When used alone, it implies `--cpu-prof`.

```console
$ node --cpu-prof-path /tmp/test.cpuprofile index.js
```

### `--diagnostic-report-directory=directory`
<!-- YAML
added: v11.8.0
@@ -78,6 +78,18 @@ Aborting instead of exiting causes a core file to be generated for analysis.
.It Fl -completion-bash
Print source-able bash completion script for Node.js.
.
.It Fl -cpu-prof
Start the V8 CPU profiler on start up, and write the CPU profile to disk
before exit. If
.Fl -cpu-prof-path
is not specified, the profile will be written to the current working directory.
.
.It Fl -cpu-prof-path
Path the V8 CPU profile generated with
.Fl -cpu-prof
will be written to. When used alone, it implies
.Fl -cpu-prof
.
.It Fl -diagnostic-report-directory
Location at which the
.Sy diagnostic report
@@ -659,6 +659,25 @@ inline profiler::V8CoverageConnection* Environment::coverage_connection() {
inline const std::string& Environment::coverage_directory() const {
return coverage_directory_;
}

inline void Environment::set_cpu_profiler_connection(
std::unique_ptr<profiler::V8CpuProfilerConnection> connection) {
CHECK_NULL(cpu_profiler_connection_);
std::swap(cpu_profiler_connection_, connection);
}

inline profiler::V8CpuProfilerConnection*
Environment::cpu_profiler_connection() {
return cpu_profiler_connection_.get();
}

inline void Environment::set_cpu_profile_path(const std::string& path) {
cpu_profile_path_ = path;
}

inline const std::string& Environment::cpu_profile_path() const {
return cpu_profile_path_;
}
#endif // HAVE_INSPECTOR

inline std::shared_ptr<HostPort> Environment::inspector_host_port() {
@@ -71,6 +71,7 @@ class AgentWriterHandle;
#if HAVE_INSPECTOR
namespace profiler {
class V8CoverageConnection;
class V8CpuProfilerConnection;
} // namespace profiler
#endif // HAVE_INSPECTOR

@@ -1129,6 +1130,13 @@ class Environment : public MemoryRetainer {

inline void set_coverage_directory(const char* directory);
inline const std::string& coverage_directory() const;

void set_cpu_profiler_connection(
std::unique_ptr<profiler::V8CpuProfilerConnection> connection);
profiler::V8CpuProfilerConnection* cpu_profiler_connection();

inline void set_cpu_profile_path(const std::string& path);
inline const std::string& cpu_profile_path() const;
#endif // HAVE_INSPECTOR

private:
@@ -1163,7 +1171,9 @@ class Environment : public MemoryRetainer {

#if HAVE_INSPECTOR
std::unique_ptr<profiler::V8CoverageConnection> coverage_connection_;
std::unique_ptr<profiler::V8CpuProfilerConnection> cpu_profiler_connection_;
std::string coverage_directory_;
std::string cpu_profile_path_;
#endif // HAVE_INSPECTOR

std::shared_ptr<EnvironmentOptions> options_;
@@ -23,10 +23,14 @@ using v8::Value;
using v8_inspector::StringBuffer;
using v8_inspector::StringView;

#ifdef __POSIX__
const char* const kPathSeparator = "/";
#else
#ifdef _WIN32
const char* const kPathSeparator = "\\/";
/* MAX_PATH is in characters, not bytes. Make sure we have enough headroom. */
#define CWD_BUFSIZE (MAX_PATH * 4)
#else
#include <climits> // PATH_MAX on Solaris.
const char* const kPathSeparator = "/";
#define CWD_BUFSIZE (PATH_MAX)
#endif

std::unique_ptr<StringBuffer> ToProtocolString(Isolate* isolate,
@@ -180,6 +184,116 @@ void V8CoverageConnection::End() {
DispatchMessage(end);
}

void V8CpuProfilerConnection::OnMessage(
const v8_inspector::StringView& message) {
Debug(env(),
DebugCategory::INSPECTOR_PROFILER,
"Receive cpu profiling message, ending = %s\n",
ending_ ? "true" : "false");
if (!ending_) {
return;
}
Isolate* isolate = env()->isolate();
HandleScope handle_scope(isolate);
Local<Context> context = env()->context();
Context::Scope context_scope(context);
Local<String> result;
if (!String::NewFromTwoByte(isolate,
message.characters16(),
NewStringType::kNormal,
message.length())
.ToLocal(&result)) {
fprintf(stderr, "Failed to convert profiling message\n");
}
WriteCpuProfile(result);
}

void V8CpuProfilerConnection::WriteCpuProfile(Local<String> message) {
const std::string& path = env()->cpu_profile_path();
CHECK(!path.empty());
std::string directory = path.substr(0, path.find_last_of(kPathSeparator));
if (directory != path) {
uv_fs_t req;
int ret = fs::MKDirpSync(nullptr, &req, directory, 0777, nullptr);
uv_fs_req_cleanup(&req);
if (ret < 0 && ret != UV_EEXIST) {
char err_buf[128];
uv_err_name_r(ret, err_buf, sizeof(err_buf));
fprintf(stderr,
"%s: Failed to create cpu profile directory %s\n",
err_buf,
directory.c_str());
return;
}
}
MaybeLocal<String> result = GetResult(message);
if (!result.IsEmpty()) {
WriteResult(path.c_str(), result.ToLocalChecked());
}
}

MaybeLocal<String> V8CpuProfilerConnection::GetResult(Local<String> message) {
Local<Context> context = env()->context();
Isolate* isolate = env()->isolate();
Local<Value> parsed;
if (!v8::JSON::Parse(context, message).ToLocal(&parsed) ||
!parsed->IsObject()) {
fprintf(stderr, "Failed to parse CPU profile result as JSON object\n");
return MaybeLocal<String>();
}

Local<Value> result_v;
if (!parsed.As<Object>()
->Get(context, FIXED_ONE_BYTE_STRING(isolate, "result"))
.ToLocal(&result_v)) {
fprintf(stderr, "Failed to get result from CPU profile message\n");
return MaybeLocal<String>();
}

if (!result_v->IsObject()) {
fprintf(stderr, "'result' from CPU profile message is not an object\n");
return MaybeLocal<String>();
}

Local<Value> profile_v;
if (!result_v.As<Object>()
->Get(context, FIXED_ONE_BYTE_STRING(isolate, "profile"))
.ToLocal(&profile_v)) {
fprintf(stderr, "'profile' from CPU profile result is undefined\n");
return MaybeLocal<String>();
}

Local<String> result_s;
if (!v8::JSON::Stringify(context, profile_v).ToLocal(&result_s)) {
fprintf(stderr, "Failed to stringify CPU profile result\n");
return MaybeLocal<String>();
}

return result_s;
}

void V8CpuProfilerConnection::Start() {
Debug(env(), DebugCategory::INSPECTOR_PROFILER, "Sending Profiler.start\n");
Isolate* isolate = env()->isolate();
Local<String> enable = FIXED_ONE_BYTE_STRING(
isolate, R"({"id": 1, "method": "Profiler.enable"})");
Local<String> start = FIXED_ONE_BYTE_STRING(
isolate, R"({"id": 2, "method": "Profiler.start"})");
DispatchMessage(enable);
DispatchMessage(start);
}

void V8CpuProfilerConnection::End() {
CHECK_EQ(ending_, false);
ending_ = true;
Debug(env(), DebugCategory::INSPECTOR_PROFILER, "Sending Profiler.stop\n");
Isolate* isolate = env()->isolate();
HandleScope scope(isolate);
Local<String> end =
FIXED_ONE_BYTE_STRING(isolate, R"({"id": 3, "method": "Profiler.stop"})");
DispatchMessage(end);
}

// For now, we only support coverage profiling, but we may add more
// in the future.
void EndStartedProfilers(Environment* env) {
@@ -190,6 +304,12 @@ void EndStartedProfilers(Environment* env) {
env, DebugCategory::INSPECTOR_PROFILER, "Ending coverage collection\n");
connection->End();
}

connection = env->cpu_profiler_connection();
if (connection != nullptr && !connection->ending()) {
Debug(env, DebugCategory::INSPECTOR_PROFILER, "Ending cpu profiling\n");
connection->End();
}
}

void StartCoverageCollection(Environment* env) {
@@ -198,6 +318,26 @@ void StartCoverageCollection(Environment* env) {
env->coverage_connection()->Start();
}

void StartCpuProfiling(Environment* env, const std::string& profile_path) {
std::string path;
if (profile_path.empty()) {
char cwd[CWD_BUFSIZE];
size_t size = CWD_BUFSIZE;
int err = uv_cwd(cwd, &size);
// TODO(joyeecheung): fallback to exec path / argv[0]
CHECK_EQ(err, 0);
CHECK_GT(size, 0);
DiagnosticFilename filename(env, "CPU", "cpuprofile");
path = cwd + std::string(kPathSeparator) + (*filename);
} else {
path = profile_path;
}
env->set_cpu_profile_path(std::move(path));
env->set_cpu_profiler_connection(
std::make_unique<V8CpuProfilerConnection>(env));
env->cpu_profiler_connection()->Start();
}

static void SetCoverageDirectory(const FunctionCallbackInfo<Value>& args) {
CHECK(args[0]->IsString());
Environment* env = Environment::GetCurrent(args);
@@ -68,6 +68,24 @@ class V8CoverageConnection : public V8ProfilerConnection {
bool ending_ = false;
};

class V8CpuProfilerConnection : public V8ProfilerConnection {
public:
explicit V8CpuProfilerConnection(Environment* env)
: V8ProfilerConnection(env) {}

void Start() override;
void End() override;
void OnMessage(const v8_inspector::StringView& message) override;
bool ending() const override { return ending_; }

private:
void WriteCpuProfile(v8::Local<v8::String> message);
v8::MaybeLocal<v8::String> GetResult(v8::Local<v8::String> message);

std::unique_ptr<inspector::InspectorSession> session_;
bool ending_ = false;
};

} // namespace profiler
} // namespace node

@@ -237,6 +237,12 @@ MaybeLocal<Value> RunBootstrapping(Environment* env) {
#endif // HAVE_INSPECTOR
}

#if HAVE_INSPECTOR
if (env->options()->cpu_prof) {
profiler::StartCpuProfiling(env, env->options()->cpu_prof_path);
}
#endif // HAVE_INSPECTOR

// Add a reference to the global object
Local<Object> global = context->Global();

@@ -314,6 +314,7 @@ void MarkBootstrapComplete(const v8::FunctionCallbackInfo<v8::Value>& args);
#if HAVE_INSPECTOR
namespace profiler {
void StartCoverageCollection(Environment* env);
void StartCpuProfiling(Environment* env, const std::string& profile_name);
void EndStartedProfilers(Environment* env);
}
#endif // HAVE_INSPECTOR
@@ -332,6 +332,18 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
&EnvironmentOptions::prof_process);
// Options after --prof-process are passed through to the prof processor.
AddAlias("--prof-process", { "--prof-process", "--" });
#if HAVE_INSPECTOR
AddOption("--cpu-prof",
"Start the V8 CPU profiler on start up, and write the CPU profile "
"to disk before exit. If --cpu-prof-path is not specified, write "
"the profile to the current working directory.",
&EnvironmentOptions::cpu_prof);
AddOption("--cpu-prof-path",
"Path the V8 CPU profile generated with --cpu-prof will be "
"written to.",
&EnvironmentOptions::cpu_prof_path);
Implies("--cpu-prof-path", "--cpu-prof");
#endif // HAVE_INSPECTOR
AddOption("--redirect-warnings",
"write warnings to file instead of stderr",
&EnvironmentOptions::redirect_warnings,
@@ -109,6 +109,10 @@ class EnvironmentOptions : public Options {
bool preserve_symlinks = false;
bool preserve_symlinks_main = false;
bool prof_process = false;
#if HAVE_INSPECTOR
std::string cpu_prof_path;
bool cpu_prof = false;
#endif // HAVE_INSPECTOR
std::string redirect_warnings;
bool throw_deprecation = false;
bool trace_deprecation = false;
@@ -0,0 +1,7 @@
'use strict';
function fib(n) {
if (n === 0 || n === 1) return n;
return fib(n - 1) + fib(n - 2);
}
fib(parseInt(process.argv[2]) || 35);
process.exit(55);
@@ -0,0 +1,7 @@
'use strict';
function fib(n) {
if (n === 0 || n === 1) return n;
return fib(n - 1) + fib(n - 2);
}
fib(parseInt(process.argv[2]) || 35);
process.kill(process.pid, "SIGINT");
@@ -0,0 +1,7 @@
'use strict';

const { Worker } = require('worker_threads');
const path = require('path');
new Worker(path.join(__dirname, 'fibonacci.js'), {
execArgv: ['--cpu-prof']
});
@@ -0,0 +1,8 @@
'use strict';
function fib(n) {
if (n === 0 || n === 1) return n;
return fib(n - 1) + fib(n - 2);
}

const n = parseInt(process.env.FIB) || 35;
process.stdout.write(`${fib(n)}\n`);

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