Skip to content

src: set an appropriate thread pool size if given --v8-pool-size=0 #45513

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
nodejs-github-bot merged 2 commits into from
Nov 21, 2022
Merged

src: set an appropriate thread pool size if given --v8-pool-size=0 #45513

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c57a161
src: set an appropriate thread pool size if given `--v8-pool-size=0`
daeyeon Nov 18, 2022
b88c1d0
fixup! src: set an appropriate thread pool size if given `--v8-pool-s…
daeyeon Nov 20, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Next Next commit
src: set an appropriate thread pool size if given --v8-pool-size=0 
It doesn't terminate when any pending V8 tasks exist if no thread
is in the pool.

This allocates one thread at least for V8's background tasks if
`--v8-pool-size=0` is given as a CLI option.

Signed-off-by: Daeyeon Jeong <daeyeon.dev@gmail.com>
  • Loading branch information
@daeyeon
daeyeon committed Nov 19, 2022
commit c57a161c373f829e69f6987cb59e9e829716c17a
7 changes: 2 additions & 5 deletions doc/api/cli.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1570,11 +1570,8 @@ added: v5.10.0

Set V8's thread pool size which will be used to allocate background jobs.

If set to `0` then V8 will choose an appropriate size of the thread pool based
on the number of online processors.

If the value provided is larger than V8's maximum, then the largest value
will be chosen.
If set to `0` then Node.js will choose an appropriate size of the thread pool
based on an estimate of the amount of parallelism.
Comment thread
daeyeon marked this conversation as resolved.

### `--watch`

Expand Down
9 changes: 9 additions & 0 deletions src/node_platform.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,13 @@ static void PlatformWorkerThread(void* data) {
}
}

static int GetActualThreadPoolSize(int thread_pool_size) {
if (thread_pool_size < 1) {
thread_pool_size = uv_available_parallelism() - 1;
}
return std::max(thread_pool_size, 1);
}

} // namespace

class WorkerThreadsTaskRunner::DelayedTaskScheduler {
Expand Down Expand Up @@ -340,6 +347,8 @@ NodePlatform::NodePlatform(int thread_pool_size,
// current v8::Platform instance.
SetTracingController(tracing_controller_);
DCHECK_EQ(GetTracingController(), tracing_controller_);

thread_pool_size = GetActualThreadPoolSize(thread_pool_size);
worker_thread_task_runner_ =
std::make_shared<WorkerThreadsTaskRunner>(thread_pool_size);
}
Expand Down
10 changes: 10 additions & 0 deletions test/parallel/test-v8-flag-pool-size-0.js
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
// Flags: --v8-pool-size=0 --expose-gc

'use strict';

require('../common');

// This verifies that V8 tasks scheduled by GC are handled on worker threads if
// `--v8-pool-size=0` is given. The worker threads are managed by Node.js'
// `v8::Platform` implementation.
globalThis.gc();