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d7452b7140
Warn when a non-existent property of an unfinished module.exports
object is being accessed, as that very often indicates the presence
of a hard-to-detect and hard-to-debug problem.
This mechanism is only used if `module.exports` is still a
regular object at the point at which the second, circular `require()`
happens.
The downside is that, temporarily, `module.exports` will have a
prototype other than `Object.prototype`, and that there may
be valid uses of accessing non-existent properties of unfinished
`module.exports` objects.
Performance of circular require calls in general is not
noticeably impacted.
confidence improvement accuracy (*) (**) (***)
module/module-loader-circular.js n=10000 3.96 % ±5.12% ±6.82% ±8.89%
Example:
$ cat a.js
'use strict';
const b = require('./b.js');
exports.fn = () => {};
$ cat b.js
'use strict';
const a = require('./a.js');
a.fn();
$ node a.js
(node:1617) Warning: Accessing non-existent property 'fn' of module exports inside circular dependency
/tmp/b.js:4
a.fn();
^
TypeError: a.fn is not a function
at Object.<anonymous> (/tmp/b.js:4:3)
[...]
PR-URL: https://github.com/nodejs/node/pull/29935
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
|
||
|---|---|---|
| .. | ||
| assert | ||
| async_hooks | ||
| buffers | ||
| child_process | ||
| cluster | ||
| crypto | ||
| dgram | ||
| dns | ||
| domain | ||
| es | ||
| events | ||
| fixtures | ||
| fs | ||
| http | ||
| http2 | ||
| misc | ||
| module | ||
| napi | ||
| net | ||
| os | ||
| path | ||
| process | ||
| querystring | ||
| streams | ||
| string_decoder | ||
| timers | ||
| tls | ||
| url | ||
| util | ||
| v8 | ||
| vm | ||
| worker | ||
| zlib | ||
| _benchmark_progress.js | ||
| _cli.js | ||
| _cli.R | ||
| _http-benchmarkers.js | ||
| _test-double-benchmarker.js | ||
| .eslintrc.yaml | ||
| common.js | ||
| compare.js | ||
| compare.R | ||
| README.md | ||
| run.js | ||
| scatter.js | ||
| scatter.R | ||
Node.js Core Benchmarks
This folder contains code and data used to measure performance of different Node.js implementations and different ways of writing JavaScript run by the built-in JavaScript engine.
For a detailed guide on how to write and run benchmarks in this directory, see the guide on benchmarks.
Table of Contents
Benchmark Directories
| Directory | Purpose |
|---|---|
| assert | Benchmarks for the assert subsystem. |
| buffers | Benchmarks for the buffer subsystem. |
| child_process | Benchmarks for the child_process subsystem. |
| crypto | Benchmarks for the crypto subsystem. |
| dgram | Benchmarks for the dgram subsystem. |
| domain | Benchmarks for the domain subsystem. |
| es | Benchmarks for various new ECMAScript features and their pre-ES2015 counterparts. |
| events | Benchmarks for the events subsystem. |
| fixtures | Benchmarks fixtures used in various benchmarks throughout the benchmark suite. |
| fs | Benchmarks for the fs subsystem. |
| http | Benchmarks for the http subsystem. |
| http2 | Benchmarks for the http2 subsystem. |
| misc | Miscellaneous benchmarks and benchmarks for shared internal modules. |
| module | Benchmarks for the module subsystem. |
| net | Benchmarks for the net subsystem. |
| path | Benchmarks for the path subsystem. |
| process | Benchmarks for the process subsystem. |
| querystring | Benchmarks for the querystring subsystem. |
| streams | Benchmarks for the streams subsystem. |
| string_decoder | Benchmarks for the string_decoder subsystem. |
| timers | Benchmarks for the timers subsystem, including setTimeout, setInterval, .etc. |
| tls | Benchmarks for the tls subsystem. |
| url | Benchmarks for the url subsystem, including the legacy url implementation and the WHATWG URL implementation. |
| util | Benchmarks for the util subsystem. |
| vm | Benchmarks for the vm subsystem. |
Other Top-level files
The top-level files include common dependencies of the benchmarks and the tools for launching benchmarks and visualizing their output. The actual benchmark scripts should be placed in their corresponding directories.
_benchmark_progress.js: implements the progress bar displayed when runningcompare.js_cli.js: parses the command line arguments passed tocompare.js,run.jsandscatter.js_cli.R: parses the command line arguments passed tocompare.R_http-benchmarkers.js: selects and runs external tools for benchmarking thehttpsubsystem.common.js: see Common API.compare.js: command line tool for comparing performance between different Node.js binaries.compare.R: R script for statistically analyzing the output ofcompare.jsrun.js: command line tool for running individual benchmark suite(s).scatter.js: command line tool for comparing the performance between different parameters in benchmark configurations, for example to analyze the time complexity.scatter.R: R script for visualizing the output ofscatter.jswith scatter plots.
Common API
The common.js module is used by benchmarks for consistency across repeated tasks. It has a number of helpful functions and properties to help with writing benchmarks.
createBenchmark(fn, configs[, options])
See the guide on writing benchmarks.
default_http_benchmarker
The default benchmarker used to run HTTP benchmarks. See the guide on writing HTTP benchmarks.
PORT
The default port used to run HTTP benchmarks. See the guide on writing HTTP benchmarks.
sendResult(data)
Used in special benchmarks that can't use createBenchmark and the object
it returns to accomplish what they need. This function reports timing
data to the parent process (usually created by running compare.js, run.js or
scatter.js).