Operation conflict between time package and file

[Minaki]

BPO	43365
Nosy	@terryjreedy, @minaki
Files	test.py: The following code can be run after commenting sleep, otherwise the file will always be empty

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-03-05.22:56:17.631>
created_at = <Date 2021-03-02.10:43:49.915>
labels = ['build', 'invalid', '3.10', 'expert-IO']
title = 'Operation conflict between time package and file'
updated_at = <Date 2021-03-05.22:56:17.629>
user = 'https://github.com/Minaki'

bugs.python.org fields:

activity = <Date 2021-03-05.22:56:17.629>
actor = 'terry.reedy'
assignee = 'none'
closed = True
closed_date = <Date 2021-03-05.22:56:17.631>
closer = 'terry.reedy'
components = ['IO']
creation = <Date 2021-03-02.10:43:49.915>
creator = 'minaki_2525'
dependencies = []
files = ['49843']
hgrepos = []
issue_num = 43365
keywords = []
message_count = 2.0
messages = ['387909', '388171']
nosy_count = 2.0
nosy_names = ['terry.reedy', 'minaki_2525']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'compile error'
url = 'https://bugs.python.org/issue43365'
versions = ['Python 3.10']

[Minaki]

"""In Python 3.9, the following code can be run after commenting sleep, otherwise the file will always be empty"""
import time

file=open("data.txt","a+")
while True:
    time.sleep(0.00001)
    file.write("test\n")
    print("add over")

[terryjreedy]

I unlinked the preliminary versions of the code minimized in the 3 post.

The posted code is buggy: it opens a file and then start an infinite loop. It has to be interrupted someway, and the file may not be properly closed and flushed to disk. When I make the loop finite and explicitly close the file, or even better, use a 'with' statement, the file is written as expected. At least on Windows, it runs noticeably slower with the sleep because the minimum sleep is 1/16 second.

Minaki, if you find a problem with unbuggy code, you can post and reopen. If you are a beginner who does not know about things like closing file, flushing to disk, and the with statement, you should post to a question and answer forum such as python-list and ask 'Is Python or my code buggy?'