Piping into the process that was ended immediately leads to exceptions with descriptors about xonsh HOT 1 OPEN

Here is tracing two cases that are the result of the current logic.

Case 1: race condition in prompt

Steps:

1. Run a | head -n0. Here -n0 leads to stop head immediately. This code will be executed:

   xonsh/xonsh/base_shell.py

   Lines 387 to 390 in 9e86938

   	tee = Tee(encoding=enc, errors=err)
   	ts0 = time.time()
   	try:
   	exc_info = run_compiled_code(code, self.ctx, None, "single")

   • Here we create Tee - wrapper for std with memory buffer.
   • And run the command with case of callable alias. It works in thread AND NOT blocking the execution.

2. While callable alias is working we achieve this line in the same code block:

   xonsh/xonsh/base_shell.py

   Line 423 in 9e86938

   tee.close()

   • Here memory buffer will be closed BUT the callable alias still executing. We have something like race condition.

3. When callable alias tries to operate with memory buffer it already closed and we see I/O operation on closed file. When I'm saying "memory buffer" I mean this memory buffer that Tee manages and _TeeStd operates:

   xonsh/xonsh/base_shell.py

   Line 264 in 9e86938

   self.memory = io.TextIOWrapper(

   
   

   xonsh/xonsh/base_shell.py

   Line 272 in 9e86938

   self.stdout = _TeeStd("stdout", self.memory)

Case 2: callable alias and loop

If we run:

for i in range(0,10):
    a | head -n0

We will have multiple randomly spreaded "Bad file descriptor" errors. I tried to trace them but gave it up because it's obvious that the errors are from intersection of multiple threads that are working at once because of head -n0 stopped immediately.