This patch speeds up the startup time and reduce the startup memory
footprint by using V8 code cache when comiling builtin modules.
The current approach is demonstrated in the `with-code-cache`
Makefile target (no corresponding Windows target at the moment).
1. Build the binary normally (`src/node_code_cache_stub.cc` is used),
by now `internalBinding('code_cache')` is an empty object
2. Run `tools/generate_code_cache.js` with the binary, which generates
the code caches by reading source code of builtin modules off source
code exposed by `require('internal/bootstrap/cache').builtinSource`
and then generate a C++ file containing static char arrays of the
code cache, using a format similar to `node_javascript.cc`
3. Run `configure` with the `--code-cache-path` option so that
the newly generated C++ file will be used when compiling the
new binary. The generated C++ file will put the cache into
the `internalBinding('code_cache')` object with the module
ids as keys
4. The new binary tries to read the code cache from
`internalBinding('code_cache')` and use it to compile
builtin modules. If the cache is used, it will put the id
into `require('internal/bootstrap/cache').compiledWithCache`
for bookkeeping, otherwise the id will be pushed into
`require('internal/bootstrap/cache').compiledWithoutCache`
This patch also added tests that verify the code cache is
generated and used when compiling builtin modules.
The binary with code cache:
- Is ~1MB bigger than the binary without code cahe
- Consumes ~1MB less memory during start up
- Starts up about 60% faster
PR-URL: https://github.com/nodejs/node/pull/21405
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gus Caplan <me@gus.host>
