## What
This PR changes Next.js to bundle its vendored React libraries so that the App Router pages can use those built-in versions.
## Why
Next.js supports both Pages and App Router and we've gone through a lot of iteration to make sure that Next.js stays flexible wrt to the version of React used: in Pages, we want to use the React provided by the user and in the App Router, to be able to use it, we need to use the canary version of React, which we've built into Next.js for convenience.
The problem stems from the fact that you can't run two different instances of React (by design).
Previously we have a dual worker setup, where we would separate completely each Next.js versions (App and Pages) so that they would not overlap with each other, however this approach was not great performance and memory wise.
We've recently tried using an ESM loader and a single process, but this change would still opt you into the React canary version if you had an app page, which breaks some assumptions.
## How
A list of the changes in this PR:
### New versions of the Next.js runtime
Since we now compile a runtime per type of page (app/route/api/pages), in order to bundle the two versions of React that we vendored, we introduced a new type of bundle suffixed by `-experimental`. This bundle will have the bleeding edge React needed for Server Actions and Next.js will opt you in into that runtime automatically.
For internal contributors, it means that we now run a compiler for 10 subparts of Next.js:
- next_bundle_server
- next_bundle_pages_prod
- next_bundle_pages_turbo
- next_bundle_pages_dev
- next_bundle_app_turbo_experimental
- next_bundle_app_prod
- next_bundle_app_prod_experimental
- next_bundle_app_turbo
- next_bundle_app_dev_experimental
- next_bundle_app_dev
### Simplified require-hook
Since the versions of React are correctly re-routed at build time for app pages, we don't need the require hook anymore
### Turbopack changes
The bundling logic in Turbopack has been addressed to properly follow the new logic
### Changes to the shared contexts system
Some context files need to have a shared instance between the rendering runtime and the user code, like the one that powers the `next/image` component. In general, the aliasing setup takes care of that but we need the require hook for code that is not compiled to reroute to the correct runtime. This only happens for pages node_modules.
A new Turbopack resolving plugin has been added to handle that logic in Turbopack.
### Misc changes
- `runtime-config` (that powers `next/config`) has been converted to an `.external` file, as it should have been
- there are some rules that have been added to the aliases to support the usage of `react-dom/server` in a server-components. We can do that now since the runtime takes care of separating the versions of React.
Co-authored-by: JJ Kasper <22380829+ijjk@users.noreply.github.com>
## What?
In Next, rendering a route involves 3 layers:
- the routing layer, which will direct the request to the correct route to render
- the rendering layer, which will take a route and render it appropriately
- the user layer, which contains the user code
In #51831, in order to optimise the boot time of Next.js, I introduced a change that allowed the routing layer to be bundled. In this PR, I'm doing the same for the rendering layer. This is building up on @wyattjoh's work that initially split the routing and the rendering layer into separate entry-points.
The benefits of having this approach is that this allows us to compartmentalise the different part of Next, optimise them individually and making sure that serving a request is as efficient as possible, e.g. rendering a `pages` route should not need code from the `app router` to be used.
There are now 4 different rendering runtimes, depending on the route type:
- app pages: for App Router pages
- app routes: for App Router route handlers
- pages: for legacy pages
- pages api: for legacy API routes
This change should be transparent to the end user, beside faster cold boots.
## Notable changes
Doing this change required a lot of changes for Next.js under the hood in order to make the different layers play well together.
### New conventions for externals/shared modules
The big issue of bundling the rendering runtimes is that the user code needs to be able to reference an instance of a module/value created in Next during the render. This is the case when the user wants to access the router context during SSR via `next/link` for example; when you call `useContext(value)` the value needs to be the exact same reference to one as the one created by `createContext` earlier.
Previously, we were handling this case by making all files from Next that were affected by this `externals`, meaning that we were marking them not to be bundled.
**Why not keep it this way?**
The goal of this PR as stated previously was to make the rendering process as efficient as possible, so I really wanted to avoid extraneous fs reads to unoptimised code.
In order to "fix" it, I introduced two new conventions to the codebase:
- all files that explicitly need to be shared between a rendering runtime and the user code must be suffixed by `.shared-runtime` and exposed via adding a reference in the relevant `externals` file. At compilation time, a reference to a file ending with this will get re-written to the appropriate runtime.
- all files that need to be truly externals need to be suffixed by `.external`. At compilation time, a reference to it will stay as-is. This special case is needed mostly only for the async local storages that need to be shared with all three layers of Next.
As a side effect, we should be bundling more of the Next code in the user bundles, so it should be slightly more efficient.
### App route handlers are compiled on their own layer
App route handlers should be compiled in their own layer, this allows us to separate more cleanly the compilation logic here (we don't need to run the RSC logic for example).
### New rendering bundles
We now generate a prod and a dev bundle for:
- the routing server
- the app/pages SSR rendering process
- the API routes process
The development bundle is needed because:
- there is code in Next that relies on NODE_ENV
- because we opt out of the logic referencing the correct rendering runtime in dev for a `shared-runtime` file. This is because we don't need to and that Turbopack does not support rewriting an external to something that looks like this `require('foo').bar.baz` yet. We will need to fix that when Turbopack build ships.
### New development pipeline
Bundling Next is now required when developing on the repo so I extended the taskfile setup to account for that. The webpack config for Next itself lives in `webpack.config.js` and contains the logic for all the new bundles generated.
### Misc changes
There are some misc reshuffling in the code to better use the tree shaking abilities that we can now use.
fixes NEXT-1573
Co-authored-by: Alex Kirszenberg <1621758+alexkirsz@users.noreply.github.com>
Alias all existing imports from `next/dist/..` to `next/dist/esm` for edge compiler. So that we don't need checking for `process.env.NEXT_RUNTIME === 'edge'` or passing down `nextRuntime` to decide wether the esm or cjs asset to require
This will also fix the issue that some layouts hook are been included twice into the bundle with cjs and esm bundle in edge runtime, now only esm chunk will be bundled in server.
Re-do of https://github.com/vercel/next.js/pull/40251
Edge SSR'd routes cold boot performances are proportional to the
executed code size.
In order to improve it, we are trying to optimize for the bundle size of
a packed Edge SSR route.
This PR adds ESM compilation targets for all Next.js dist packages and
use them to bundle Edge SSR'd route.
This allows us to leverage the better tree shaking/DCE for ESM modules
in webpack in order to decrease the overall bundle size.
This PR also enables minifying Edge SSR routes. Since we don't control
which minifier might be used later (if any), it's best if we provide an
already optimised bundle.
<img width="903" alt="image"
src="https://user-images.githubusercontent.com/11064311/190005211-b7cb2c58-a56a-44b0-8ee4-fd3f603e41bd.png">
This is a 10ms cold boot win per my benchmarking script, which I'll put
in a subsequent PR.
Not done yet:
- ~~swap exported requires in `next/link` (and others) etc to point them
to the esm modules version~~
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- [ ] Related issues linked using `fixes #number`
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- [ ] Errors have helpful link attached, see `contributing.md`
- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The examples guidelines are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Shu Ding <g@shud.in>
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Thanks for opening a PR! Your contribution is much appreciated.
To make sure your PR is handled as smoothly as possible we request that
you follow the checklist sections below.
Choose the right checklist for the change that you're making:
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## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see `contributing.md`
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Shu Ding <g@shud.in>
This reverts commit 11deaaa82b.
Temporarily reverts the above commit due to breaking middleware/edge
functions once deployed.
Fixes:
https://github.com/vercel/next.js/actions/runs/3133433920/jobs/5087331787
cc @shuding @feedthejim
```sh
[GET] /blog/first
13:56:56:61
2022-09-27T20:56:56.671Z 61d43a6a-34a1-40c0-b71f-4ae5d1918431 ERROR /var/task/node_modules/next/dist/esm/client/router.js:1
/* global window */ import React from 'react';
^^^^^^
SyntaxError: Cannot use import statement outside a module
at Object.compileFunction (node:vm:352:18)
at wrapSafe (node:internal/modules/cjs/loader:1033:15)
at Module._compile (node:internal/modules/cjs/loader:1069:27)
at Object.Module._extensions..js (node:internal/modules/cjs/loader:1159:10)
at Module.load (node:internal/modules/cjs/loader:981:32)
at Function.Module._load (node:internal/modules/cjs/loader:822:12)
at Module.require (node:internal/modules/cjs/loader:1005:19)
at require (node:internal/modules/cjs/helpers:102:18)
at Object.<anonymous> (/var/task/node_modules/next/router.js:3:7)
at Module._compile (node:internal/modules/cjs/loader:1105:14)
```
# Context
Edge SSR'd routes cold boot performances are proportional to the
executed code size.
In order to improve it, we are trying to optimize for the bundle size of
a packed Edge SSR route.
This PR adds ESM compilation targets for all Next.js dist packages and
use them to bundle Edge SSR'd route.
This allows us to leverage the better tree shaking/DCE for ESM modules
in webpack in order to decrease the overall bundle size.
This PR also enables minifying Edge SSR routes. Since we don't control
which minifier might be used later (if any), it's best if we provide an
already optimised bundle.
<img width="903" alt="image"
src="https://user-images.githubusercontent.com/11064311/190005211-b7cb2c58-a56a-44b0-8ee4-fd3f603e41bd.png">
This is a 10ms cold boot win per my benchmarking script, which I'll put
in a subsequent PR.
Not done yet:
- ~~swap exported requires in `next/link` (and others) etc to point them
to the esm modules version~~
<!--
Thanks for opening a PR! Your contribution is much appreciated.
In order to make sure your PR is handled as smoothly as possible we
request that you follow the checklist sections below.
Choose the right checklist for the change that you're making:
-->
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
## Feature
- [x] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The examples guidelines are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)
Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Shu Ding <g@shud.in>
