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Using File.read with async in Windows causes Bad file descriptor Exception #206
Description
Description
When I use File.read in Async, the following exception is thrown.
require "async"
Async do |task|
task.async do
p File.read("README.md")
end
end 0.0s warn: Async::Task [oid=0x348] [ec=0x35c] [pid=4880] [2022-12-06 13:02:07 +0900]
| Task may have ended with unhandled exception.
| Errno::EBADF: Bad file descriptor
| → <internal:io> 63
| C:/Ruby31-x64/lib/ruby/gems/3.1.0/gems/io-event-1.1.3/lib/io/event/selector/select.rb 206
This behavior is only observed in Windows with ruby 3.1.
Also, I reproduced this behavior in GitHub Actions here.
Sample Code
require "async"
Async do |task|
task.async do
p File.read("README.md")
end
endExpected Behavior
No exception is thrown, and the content of README.md is shown on console.
Actual Behavior
Errno::EBADF: Bad file descriptor exception is thrown, and the task stops there.
Versions
Windows 10 Home 21H2
ruby 3.1.1p18 (2022-02-18 revision 53f5fc4236) [x64-mingw-ucrt]
async (2.3.0)
Activity
ioquatix commentedon Dec 6, 2022
I guess it's a limitation of Windows. The best thing we can do is try to avoid doing any kind of asynchronous file IO, which isn't supported anyway in this situation. The simple solution is to just detect windows and skip any kind of asynchronous
io_readandio_writeoperations.phenylshima commentedon Dec 6, 2022
Then I'll just try detecting Windows and avoid async file IO on it...
Thank you for your comment and advice.
I'm closing this issue.
ioquatix commentedon Dec 6, 2022
Async on Windows is a work in progress. The first part was to get
io-eventworking which is tested, but async itself is not well tested on Windows yet. We should probably disable theio_readandio_writehooks on Windows for this reason. I want to leave this issue open until we do that.ioquatix commentedon Dec 6, 2022
#184 now includes the above.