Flush after writting JSON to stdout

[ycrack84]

In some cases, in resulting JSON is missing last few lines or output is missing entirely.
This could be fixed by flushing buffer to file after write

gallery-dl/gallery_dl/util.py

Line 113 in 90491ab

fp.write("\n")

fp.flush()

[mikf]

Writing a newline to stdout (as well as exiting the process) already causes a flush() to happen,
as can be seen with the following example code:

import sys
import time

for i in range(3):
    sys.stdout.write("foo")
    time.sleep(1)

sys.stdout.write("\n")  # causes "foofoofoo" to appear
sys.stdout.write("bar")  # doesn't get shown/flushed until process ends
time.sleep(3)

What exactly are "some cases"? What are you trying to do where it doesn't work?

[ycrack84]

Hi @mikf sorry for late response.
Executing command gallery-dl -j "https://www.imagefap.com/profile/Nika" prints nothing to console, but it depends on the size of resulting json and buffer size.

I found out that problem is only with git bash (mingw64). Windows cmd and powershell prints whole json (without explicit flush).
The only way to fix it for git bash is to flush buffer after write.

gallery-dl v1.14.1
OS: Win 10
Python: 3.8.2

[mikf]

There are apparently some problems with cygwin/mingw and Python's detection whether stdout etc is a TTY or not and its auto-flush behavior, which I've never heard about before:

• https://stackoverflow.com/questions/3250749/using-windows-python-from-cygwin
• https://superuser.com/questions/1281718/cygwin-doesnt-display-python-output

Well, I've now added an explicit flush() after calling dump_json() when displaying the results for -j/--dump-json (1b3870a). I hope that helps.