Fixes #26179.
The original error reported in that issue is fixed on canary, but in
local testing on my windows machine, `next build` would just hang
forever.
After some digging, what happens is that at some point in next build,
readFile promises (from `fs/promises` ) just never resolve, and so next
hangs.
It turns out the issue is saturating tokio's blocking task thread pool.
We previously limited the number of blocking threads to 32, and at some
point those threads are all in use and there's no thread available for
the file reads.
What's taking up all of those threads? The answer turns out to be
`tokio::process`. On windows, child process stdio uses the blocking
threadpool: https://github.com/tokio-rs/tokio/pull/4824. When you poll
the child's stdio on windows, it spawns a blocking task per poll, and
calls `std::io::Read::read` in the blocking context. That call can block
until data is available.
Putting it all together, what happens is that Next.js spawns `2 * the
number of CPU cores` deno child subprocesses to do work. We implement
`child_process` with `tokio::process`. When the child processes' stdio
get polled, blocking tasks get spawned, and those blocking tasks might
block until data is available. So if you have 16 cores (as I do), there
are going to be potentially >32 blocking task threadpool threads taken
just by the child processes. That leaves no room for other tasks to make
progress
---
To fix this, for now, increase the size of the blocking threadpool on
windows. 4 * the number of CPU cores should be enough to leave room for
other tasks to make progress.
Longer term, this can be fixed more properly when we handroll our own
subprocess code (needed for detached processes and additional pipes on
windows).
1. Generally we should prefer to use the `log` crate.
2. I very often accidentally commit `eprintln`s.
When we should use `println` or `eprintln`, it's not too bad to be a bit
more verbose and ignore the lint rule.
This commit adds ability to print metrics of the Tokio
runtime to the console by passing "DENO_TOKIO_METRICS=1"
env var.
Metrics will be printed every second, but this can be changed
by "DENO_TOKIO_METRICS_INTERVAL=500" env var.
Partially supersedes #19016.
This migrates `spawn` and `spawn_blocking` to `deno_core`, and removes
the requirement for `spawn` tasks to be `Send` given our single-threaded
executor.
While we don't need to technically do anything w/`spawn_blocking`, this
allows us to have a single `JoinHandle` type that works for both cases,
and allows us to more easily experiment with alternative
`spawn_blocking` implementations that do not require tokio (ie: rayon).
Async ops (+~35%):
Before:
```
time 1310 ms rate 763358
time 1267 ms rate 789265
time 1259 ms rate 794281
time 1266 ms rate 789889
```
After:
```
time 956 ms rate 1046025
time 954 ms rate 1048218
time 924 ms rate 1082251
time 920 ms rate 1086956
```
HTTP serve (+~4.4%):
Before:
```
Running 10s test @ http://localhost:4500
2 threads and 10 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 68.78us 19.77us 1.43ms 86.84%
Req/Sec 68.78k 5.00k 73.84k 91.58%
1381833 requests in 10.10s, 167.36MB read
Requests/sec: 136823.29
Transfer/sec: 16.57MB
```
After:
```
Running 10s test @ http://localhost:4500
2 threads and 10 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 63.12us 17.43us 1.11ms 85.13%
Req/Sec 71.82k 3.71k 77.02k 79.21%
1443195 requests in 10.10s, 174.79MB read
Requests/sec: 142921.99
Transfer/sec: 17.31MB
```
Suggested-By: alice@ryhl.io
Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>
This commit moves Deno JS runtime, ops, permissions and
inspector implementation to new "deno_runtime" crate located
in "runtime/" directory.
Details in "runtime/README.md".
Co-authored-by: Ryan Dahl <ry@tinyclouds.org>
