Bug #17415
closedIO read gets blocked with Fiber Scheduler on Windows
Description
Here is the given example code for reproduction the bug:
rd, wr = IO.pipe
scheduler = Evt::Scheduler.new # Any scheduler including the test scheduler in the ruby repo could reproduce the same problem.
message = nil
Fiber.set_scheduler scheduler
Fiber.schedule do
wr.write(MESSAGE)
wr.close
end
Fiber.schedule do
message = rd.read(20)
rd.close
end
scheduler.run
assert_equal MESSAGE, message
assert rd.closed?
assert wr.closed?
When running under Linux, FreeBSD or macOS, the code works fine. But when running under Windows:
#...
Fiber.schedule do
message = rd.read(20) # !!! -> Got blocked here
rd.close
end
#...
Since some of the files don't support non-blocking on Windows, I double checked with the following code:
a, b = IO.pipe
b.write_nonblock("Test")
a.read_nonblock(4) # => "Test"
which works totally fine on Windows. I suppose some kind of IO non-blocking setup is not working properly under Windows.
Still investigating the details for patching...
Updated by dsh0416 (Delton Ding) almost 4 years ago
- ruby -v changed from ruby 3.0.0rc1 to ruby 3.0.0dev (2020-12-19 master 4735a5b9d2) [x64-mingw32]
Updated by dsh0416 (Delton Ding) almost 4 years ago
- Subject changed from IO read blocking with Fiber Scheduler on Windows to IO read gets blocked with Fiber Scheduler on Windows
Updated by zverok (Victor Shepelev) almost 4 years ago
https://docs.ruby-lang.org/en/master/doc/scheduler_md.html#label-IO
By default, I/O is non-blocking. Not all operating systems support non-blocking I/O. Windows is a notable example where socket I/O can be non-blocking but pipe I/O is blocking.
Updated by dsh0416 (Delton Ding) almost 4 years ago
zverok (Victor Shepelev) wrote in #note-3:
https://docs.ruby-lang.org/en/master/doc/scheduler_md.html#label-IO
By default, I/O is non-blocking. Not all operating systems support non-blocking I/O. Windows is a notable example where socket I/O can be non-blocking but pipe I/O is blocking.
Ah. I tested it again with UDPSocket, and everything works fine. It looks like it is the problem mentioned in the scheduler docs. Thank you so much. I think we could close the issue.
Updated by jeremyevans0 (Jeremy Evans) almost 4 years ago
- Status changed from Open to Closed