ngcc creates typically two `ts.Program` instances for each entry-point,
one for processing sources and another one for processing the typings.
The creation of these programs is somewhat expensive, as it concerns
module resolution and parsing of source files.
This commit implements several layers of caching to optimize the
creation of programs:
1. A shared module resolution cache across all entry-points within a
single invocation of ngcc. Both the sources and typings program
benefit from this cache.
2. Sharing the parsed `ts.SourceFile` for a single entry-point between
the sources and typings program.
3. Sharing parsed `ts.SourceFile`s of TypeScript's default libraries
across all entry-points within a single invocation. Some of these
default library typings are large and therefore expensive to parse,
so sharing the parsed source files across all entry-points offers
a significant performance improvement.
Using a bare CLI app created using `ng new` + `ng add @angular/material`,
the above changes offer a 3-4x improvement in ngcc's processing time
when running synchronously and ~2x improvement for asynchronous runs.
PR Close#38840
The `Logger` interface and its related classes are general purpose
and could be used by other tooling. Moving it into ngtsc is a more
suitable place from which to share it - similar to the FileSystem stuff.
PR Close#37114
Now that `ngcc/src/ngcc_options` imports `FileWriter` type, there is a
circular dependency detected by the `ts-circular-deps:check` lint check:
```
ngcc/src/ngcc_options.ts
→ ngcc/src/writing/file_writer.ts
→ ngcc/src/packages/entry_point_bundle.ts
→ ngcc/src/ngcc_options.ts
```
This commit moves the `PathMappings` type (and related helpers) to a
separate file to avoid the circular dependency.
NOTE:
The circular dependency was only with taking types into account. There
was no circular dependency for the actual (JS) code.
PR Close#36626
Previously, when running in parallel mode and a worker process crashed
while processing a task, it was not possible for ngcc to continue
without risking ending up with a corrupted entry-point and therefore it
exited with an error. This, for example, could happen when a worker
process received a `SIGKILL` signal, which was frequently observed in CI
environments. This was probably the result of Docker killing processes
due to increased memory pressure.
One factor that amplifies the problem under Docker (which is often used
in CI) is that it is not possible to distinguish between the available
CPU cores on the host machine and the ones made available to Docker
containers, thus resulting in ngcc spawning too many worker processes.
This commit addresses these issues in the following ways:
1. We take advantage of the fact that files are written to disk only
after an entry-point has been fully analyzed/compiled. The master
process can now determine whether a worker process has not yet
started writing files to disk (even if it was in the middle of
processing a task) and just put the task back into the tasks queue if
the worker process crashes.
2. The master process keeps track of the transformed files that a worker
process will attempt to write to disk. If the worker process crashes
while writing files, the master process can revert any changes and
put the task back into the tasks queue (without risking corruption).
3. When a worker process crashes while processing a task (which can be a
result of increased memory pressure or too many worker processes),
the master process will not try to re-spawn it. This way the number
or worker processes is gradually adjusted to a level that can be
accomodated by the system's resources.
Examples of ngcc being able to recover after a worker process crashed:
- While idling: https://circleci.com/gh/angular/angular/682197
- While compiling: https://circleci.com/gh/angular/angular/682209
- While writing files: https://circleci.com/gh/angular/angular/682267
Jira issue: [FW-2008](https://angular-team.atlassian.net/browse/FW-2008)
Fixes#36278
PR Close#36626
This commit enhances the `CompileFn`, which is used to process each
entry-point, to support running a passed-in callback (and wait for it to
complete) before proceeding with writing the transformed files to disk.
This functionality is currently not used. In a subsequent commit, it
will be used for passing info from worker processes to the master
process that will allow ngcc to recover when a worker process crashes in
the middle of processing a task.
PR Close#36626
Previously, the "Compiling <entryPoint>" log message was printed before
starting to analyze and transform files, but after creating the
`EntryPointBundle` (which includes creating the TS program).
Since creating the `EntryPointBundle` involves some work, it is more
accurate to move the log message before creating the bundle.
PR Close#36626
