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Original file line number Diff line number Diff line change
@@ -1,24 +1,24 @@
# Investigating memory leaks with valgrind
# Investigating memory leaks with Valgrind

A Node.js process may run out of memory due to excessive consumption of
native memory. Native Memory is memory which is not managed by the
V8 Garbage collector and is allocated either by the Node.js runtime, its
dependencies or native [addons](https://nodejs.org/docs/latest/api/n-api.html).

This guide provides information on how to use valgrind to investigate these
This guide provides information on how to use Valgrind to investigate these
issues on Linux platforms.

## valgrind
## Valgrind

[Valgrind](https://valgrind.org/docs/manual/quick-start.html) is a
tool available on Linux distributions which can be used to investigate
memory usage including identifying memory leaks (memory which is
allocated and not freed) and other memory related problems
like double freeing memory.

To use valgrind:
To use Valgrind:

* Be patient, running under valgrind slows execution significantly
* Be patient, running under Valgrind slows execution significantly
due to the checks being performed.
* Reduce your test case to the smallest reproduce. Due to the slowdown it is
important to run the minimum test case in order to be able to do it in
Expand All @@ -35,7 +35,7 @@ apt-get install valgrind

## Invocation

The simplest invocation of valgrind is:
The simplest invocation of Valgrind is:

```console
valgrind node test.js
Expand Down Expand Up @@ -317,7 +317,7 @@ From the stack trace we can tell that the leak came from a native addon:

What we can't tell is where in the native addon the memory is being
allocated. This is because by default the addon is compiled without
the debug symbols which valgrind needs to be able to provide more
the debug symbols which Valgrind needs to be able to provide more
information.

## Enabling debug symbols to get more information
Expand Down Expand Up @@ -345,7 +345,7 @@ npm install --debug
npm rebuild
```

The next step is to run valgrind after the rebuild. This time the information
The next step is to run Valgrind after the rebuild. This time the information
for the leaking location includes the name of the source file and the
line number:

Expand Down Expand Up @@ -409,7 +409,7 @@ its symbols using `-rdynamic` so that they can be used by addons. If the stack
gives you enough information to track down where the leak is, that's great,
otherwise the next step is to compile a debug build of Node.js.

To get additional information with valgrind:
To get additional information with Valgrind:

* Check out the Node.js source corresponding to the release that you
want to debug. For example:
Expand All @@ -432,7 +432,7 @@ make -j4
`./configure --debug`, two binaries will have been built when `make` was run.
You must use the one which is in `out/Debug`.

Running valgrind using the debug build of Node.js shows:
Running Valgrind using the debug build of Node.js shows:

```console
==44112== 592 bytes in 1 blocks are possibly lost in loss record 26 of 27
Expand All @@ -450,3 +450,6 @@ Running valgrind using the debug build of Node.js shows:

Now we can see the specific file name and line in the Node.js code which
caused the allocation (inspector\_agent.cc:140).

Thusly, we can examine the line (and its surrounding code) in order
to find a potential solution for the memory leak.
10 changes: 6 additions & 4 deletions doc/contributing/maintaining-the-build-files.md
Original file line number Diff line number Diff line change
Expand Up @@ -13,17 +13,17 @@ There are three main build files that may be directly run when building Node.js:
create platform-dependent build files. Its output is usually in one of these
formats: Makefile, MSbuild, ninja, or XCode project files (the main
Makefile mentioned below is maintained separately by humans). For a detailed
guide on this script, see [configure](#configure).
guide on this script, see [configure][].
* `vcbuild.bat`: A Windows Batch Script that locates build tools, provides a
subset of the targets available in the [Makefile](#makefile), and a few
subset of the targets available in the [Makefile][], and a few
targets of its own. For a detailed guide on this script, see
[vcbuild.bat](#vcbuildbat).
* `Makefile`: A Makefile that can be run with GNU Make. It provides a set of
targets that build and test the Node.js binary, produce releases and
documentation, and interact with the CI to run benchmarks or tests. For a
detailed guide on this file, see [Makefile](#makefile).
detailed guide on this file, see [Makefile][].

On Windows `vcbuild.bat` runs [configure](#configure) before building the
On Windows `vcbuild.bat` runs [configure][] before building the
Node.js binary, on other systems `configure` must be run manually before running
`make` on the `Makefile`.

Expand Down Expand Up @@ -58,3 +58,5 @@ maintained by humans. This is not usually run on Windows, where
of this option.

[GYP]: https://gyp.gsrc.io/docs/UserDocumentation.md
[Makefile]: #makefile
[configure]: #configure
27 changes: 18 additions & 9 deletions doc/contributing/maintaining-types-for-nodejs.md
Original file line number Diff line number Diff line change
@@ -1,11 +1,11 @@
# Maintaining types for Node.js

While JavaScript is an untyped language, there are a number of complementary
technologies like [TypeScript](https://www.typescriptlang.org/) and
[Flow](https://flow.org/) which allow developers to use types within their
technologies like [TypeScript][] and
[Flow][] which allow developers to use types within their
JavaScript projects. While many people don't use types, there are enough
who do that the project has agreed it's important to work towards having
[suitable types for end-users](https://github.com/nodejs/node/blob/master/doc/contributing/technical-priorities.md#suitable-types-for-end-users).
[suitable types for end-users][].

## High level approach

Expand All @@ -14,7 +14,7 @@ from shipping them with the Node.js runtime to having them be externally
maintained.

The different options were discussed as part of the
[next-10](https://github.com/nodejs/next-10/blob/main/meetings/summit-nov-2021.md#suitable-types-for-end-users)
[next-10][]
effort and it was agreed that maintaining them externally is the best approach.
Some of the advantages to this approach include:

Expand All @@ -34,22 +34,22 @@ The agreement was that the ideal flow would be as follows:

When you run `make doc` the canonical markdown files used to
document the Node.js APIs in the
[doc/api](https://github.com/nodejs/node/tree/master/doc/api)
[doc/api][]
directory are converted to both an `.html` file and a `.json` file.

As part of the regular build/release process both the `html` and
`json` files are published to [nodejs.org](https://nodejs.org/en/docs/).
`json` files are published to [nodejs.org][].

The generator that does the conversion is in the
[tools/doc](https://github.com/nodejs/node/tree/master/tools/doc)
[tools/doc][]
directory.

## Markdown structure

The constraints required on the markdown files in the
[doc/api](https://github.com/nodejs/node/tree/master/doc/api) directory
[doc/api][] directory
in order to be able to generate the JSON files are defined in the
[documentation-style-guide](https://github.com/nodejs/node/blob/master/doc/README.md#documentation-style-guide).
[documentation-style-guide][].

## Planned changes (as of Jan 1 2022)

Expand All @@ -61,3 +61,12 @@ afterwards.
There is an ongoing effort to add additional markdown constraints and
then update the flow in order to be able to generate a better
JSON output.

[doc/api]: https://github.com/nodejs/node/tree/master/doc/api
[documentation-style-guide]: https://github.com/nodejs/node/blob/master/doc/README.md#documentation-style-guide
[tools/doc]: https://github.com/nodejs/node/tree/master/tools/doc
[nodejs.org]: https://nodejs.org/en/docs/
[next-10]: https://github.com/nodejs/next-10/blob/main/meetings/summit-nov-2021.md#suitable-types-for-end-users
[suitable types for end users]: https://github.com/nodejs/node/blob/master/doc/contributing/technical-priorities.md#suitable-types-for-end-users
[Flow]: https://flow.org/
[TypeScript]: https://www.typescriptlang.org/