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lib: speed up require(), phase 2
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Replace calls to fs.readFileSync() with an internal variant that does
not create Error objects on failure and is a bit speedier in general.

A secondary benefit is that it improves start-up times in the debugger
because it no longer emits thousands of exception debug events.

On a medium-sized application[0], this commit and its predecessor reduce
start-up times from about 1.5s to 0.5s and reduce the number of start-up
exceptions from ~6100 to 32, half of them internal to the application.

[0] https://github.com/strongloop/loopback-sample-app

PR-URL: #1801
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
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bnoordhuis committed May 27, 2015
1 parent b14fd1a commit 1bbf8d0
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Showing 2 changed files with 52 additions and 4 deletions.
9 changes: 5 additions & 4 deletions lib/module.js
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ const runInThisContext = require('vm').runInThisContext;
const assert = require('assert').ok;
const fs = require('fs');
const path = require('path');
const internalModuleReadFile = process.binding('fs').internalModuleReadFile;
const internalModuleStat = process.binding('fs').internalModuleStat;


Expand Down Expand Up @@ -65,10 +66,10 @@ function readPackage(requestPath) {
return packageMainCache[requestPath];
}

try {
var jsonPath = path.resolve(requestPath, 'package.json');
var json = fs.readFileSync(jsonPath, 'utf8');
} catch (e) {
var jsonPath = path.resolve(requestPath, 'package.json');
var json = internalModuleReadFile(jsonPath);

if (json === undefined) {
return false;
}

Expand Down
47 changes: 47 additions & 0 deletions src/node_file.cc
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,8 @@
# include <io.h>
#endif

#include <vector>

namespace node {

using v8::Array;
Expand Down Expand Up @@ -433,6 +435,50 @@ Local<Value> BuildStatsObject(Environment* env, const uv_stat_t* s) {
return handle_scope.Escape(stats);
}

// Used to speed up module loading. Returns the contents of the file as
// a string or undefined when the file cannot be opened. The speedup
// comes from not creating Error objects on failure.
static void InternalModuleReadFile(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);

CHECK(args[0]->IsString());
node::Utf8Value path(env->isolate(), args[0]);

FILE* const stream = fopen(*path, "rb");
if (stream == nullptr) {
return;
}

std::vector<char> chars;
while (!ferror(stream)) {
const size_t kBlockSize = 32 << 10;
const size_t start = chars.size();
chars.resize(start + kBlockSize);
const size_t numchars = fread(&chars[start], 1, kBlockSize, stream);
if (numchars < kBlockSize) {
chars.resize(start + numchars);
}
if (numchars == 0) {
break;
}
}

CHECK_EQ(false, ferror(stream));
CHECK_EQ(0, fclose(stream));

size_t start = 0;
if (chars.size() >= 3 && 0 == memcmp(&chars[0], "\xEF\xBB\xBF", 3)) {
start = 3; // Skip UTF-8 BOM.
}

Local<String> chars_string =
String::NewFromUtf8(env->isolate(),
&chars[start],
String::kNormalString,
chars.size() - start);
args.GetReturnValue().Set(chars_string);
}

// Used to speed up module loading. Returns 0 if the path refers to
// a file, 1 when it's a directory or < 0 on error (usually -ENOENT.)
// The speedup comes from not creating thousands of Stat and Error objects.
Expand Down Expand Up @@ -1161,6 +1207,7 @@ void InitFs(Handle<Object> target,
env->SetMethod(target, "rmdir", RMDir);
env->SetMethod(target, "mkdir", MKDir);
env->SetMethod(target, "readdir", ReadDir);
env->SetMethod(target, "internalModuleReadFile", InternalModuleReadFile);
env->SetMethod(target, "internalModuleStat", InternalModuleStat);
env->SetMethod(target, "stat", Stat);
env->SetMethod(target, "lstat", LStat);
Expand Down

1 comment on commit 1bbf8d0

@gx0r
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@gx0r gx0r commented on 1bbf8d0 May 28, 2015

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Fantastic!

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