This reland commit 5a32d8bc7c with a fix
for thread leak (Issue #56717): when `ThreadPool` is shutting down
asynchronously the last worker should detach itself to prevent
leaking associated low-level data structures, because no thread will
join it.
A hang in service isolate shutdown (caused by an existing bug) was fixed by commit 157a0dc7f9.
This CL turns native ports into a thin abstraction over underlying
thread pool instead of building them as full fledged MessageHandler.
This allows to easily implement a variation of native ports which can
handle messages concurrently with the given degree of concurrency.
This type of port can be used to greatly simplify implementation of
IOService - which previously had to do its own concurrency management
on top of "single threaded" native ports. This capability is exposed
as `Dart_NewConcurrentNativePort` API.
The new implementation is in general much cleaner then the old one
with one exception: `Dart_CloseNativePort` API has unfortunate design
where underlying message handler is destroyed asynchronously and
`Dart_CloseNativePort` returns immediately without waiting for pending
tasks to complete. Implementing this on top of `ThreadPool` requires
some changes to thread pool implementation.
Issue https://github.com/dart-lang/sdk/issues/55844
Closes https://github.com/dart-lang/sdk/issues/56717
TEST=ci
Change-Id: Ic68bfb60757685afd75c80a70cdec66cc13c149b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/385000
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
Vyacheslav Egorov
e2efffa005