python - Runing a script in background will hang the subprocess -

i running script launches

run_app.py >& log.out 

in run_app.py, start few subprocesses , read stdout/stderr of subprocesses through pipe. can run script fine if try put background by:

run_app.py >& log.out & 

the run_app.py hang on reading data subprocess. seems similar thread: ffmpeg hangs when run in background

my subprocess write lot might overflow pipe_buf.

however, redirecting&writing stdout/stderr file. there suggestions might prevent hanging when put script background while able save output in file instead of redirecting them /dev/null?

when background process running, standard i/o streams still connected screen , keyboard. processes suspended (stopped) if try read keyboard.

you should have message saying like: stopped (tty input). have been sent shell's stderr.

normally redirecting stdin covers problem, programs access keyboard directly rather using stdin, typically prompting password.