STINNER Victor added the comment:
> Do you want to modify IOBase.__exit__ to ignore I/O errors in close()?
Nope. On files, you want to want to know if your data has been fully written.
For a subprocess, it's different. You only expect best effort.
The BrokenPipeError exception is raised by Python when an OS function fails
with EPIPE. This exception has the same purpose than the SIGPIPE signal: warn
the application that it's now useless to send more data, the consumer will
ignore it. By the way, since Python checks the result of *all* OS functions,
SIGPIPE is simply ignored. SIGPIPE and EPIPE have the same purpose.
In the subprocess module, if we get BrokenPipeError, it means that the child
process stopped reading from stdin (closed it or the process already exited).
Popen.communicate() must close stdin, so why would we pass BrokenPipeError to
the caller? It's useless, we just stop writing and close the pipe.
Since Popen.__exit__() also closes stdin, I use the same rationale: it useless
to pass BrokenPipeError to the caller. The caller expects that the process
exited.
Anyway, we closed all pipes, it's not more possible to communicate with the
child process. The following example displays "is proc stdin closed? True":
---
import subprocess, sys
args = [sys.executable, '-c', 'pass']
proc = subprocess.Popen(args, stdin=subprocess.PIPE)
try:
with proc:
proc.stdin.write(b'x' * (2**20))
except BrokenPipeError:
pass
print("is proc stdin closed?", proc.stdin.closed)
---
See also: "Why does SIGPIPE exist?"
https://stackoverflow.com/questions/8369506/why-does-sigpipe-exist
----------
nosy: +neologix
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