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doc: Add useful V8 option section #32262

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doc: Add useful V8 option section #32262

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doc: add useful v8 option section
nimit95 Mar 14, 2020
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doc: add useful v8 option section
nimit95 Mar 14, 2020
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Update doc/api/cli.md
nimit95 Mar 17, 2020
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Update doc/api/cli.md
nimit95 Mar 17, 2020
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doc: add to cli.md V8 options
nimit95 Mar 17, 2020
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doc: fix trailing whitespace in cli.md
nimit95 Mar 17, 2020
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doc: update cli.md for fixes
nimit95 Mar 17, 2020
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fix language cli.md
nimit95 Apr 3, 2020
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fix example formatting
nimit95 Apr 6, 2020
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22 changes: 22 additions & 0 deletions doc/api/cli.md
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Expand Up @@ -1385,6 +1385,28 @@ threadpool by setting the `'UV_THREADPOOL_SIZE'` environment variable to a value
greater than `4` (its current default value). For more information, see the
[libuv threadpool documentation][].

## Useful V8 options

V8 has its own set of CLI options. Any V8 CLI option that is provided to `node` will
be passed on to V8 to handle. V8's options have _no stability guarantee_.
The V8 team themselves don't consider them to be part of their formal API,
and reserve the right to change them at any time. The Node.js team does not
consider them covered by the Node.js stability guarantees. Many of the V8
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and reserve the right to change them at any time. The Node.js team does not
consider them covered by the Node.js stability guarantees. Many of the V8
and reserve the right to change them at any time. Likewise, they are not
covered by the Node.js stability guarantees. Many of the V8

options are of interest only to V8 developers. Despite this, there is a small
set of V8 options that are widely applicable to the Node.js, and they are
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set of V8 options that are widely applicable to the Node.js, and they are
set of V8 options that are widely applicable to Node.js, and they are

documented here. V8 options that are allowed are:
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documented here. V8 options that are allowed are:
documented here:


### `--max-old-space-size=SIZE` (in Mbytes)

Sets the max memory size of V8 old memory section. As memory
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Sets the max memory size of V8 old memory section. As memory
Sets the max memory size of V8's old memory section. As memory

consumption approaches the limit, V8 will spend more time on
garbage collection in an effort to free unused memory.

On a machine with 2GB of memory it suggested to set 1.5GB
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@mscdex mscdex Mar 17, 2020 •
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On a machine with 2GB of memory it suggested to set 1.5GB
On a machine with 2GB of memory it is suggested to set this to 1536 (1.5GB)

to leave some memory for other uses and avoid swapping.

E.g. `node --max-old-space-size=1536 index.js`
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Optional nit: Delete this line.

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@nimit95 nimit95 Apr 3, 2020 •
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I personally feel an example helps a lot when being introduced to a flag. It clearly shows how to pass an argument. @Trott

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I personally feel an example helps a lot when being introduced to a flag

If we want to provide an example, it should conform with the formatting of the other examples provided elsewhere in the doc. Otherwise, each entry is inventing its own example formatting, and we definitely do not want that. The existing format is more useful than this as it provides context, such as what the anticipated output might look like. So, this example might show the error one might get if running without the flag, then show the command succeeding with the flag.

(That said, most of our entries do not contain examples and that seems appropriate in this document.)

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Totally agree with your point, Can you point me to some of the correct existing formats?
What I see a mixture of formats, some given below

  1. node --name-of-flag index.mjs
  2. node --name-of-flag

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I don't mean the format of the command itself. I mean the markdown formatting that denotes an example.

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

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@nimit95 nimit95 Apr 8, 2020 •
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@Trott can you check out the formatting once now.


[`--openssl-config`]: #cli_openssl_config_file
[`Buffer`]: buffer.html#buffer_class_buffer
[`SlowBuffer`]: buffer.html#buffer_class_slowbuffer
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