No build time for new build system in Sublime Text 3 - build

Question

I successfully added python3 as a new build system as follows:
{
"cmd": ["python3", "-i", "-u", "$file"],
"file_regex": "^[ ]File \"(...?)\", line ([0-9]*)",
"selector": "source.python"
}
I couldn't get any build time output in python3 system but I can in other build systems. Any idea would be appreciated. Thank you.

Answer 1

The reason you don't see a build time is that you're specifying -i as an argument to python3. That makes it interactive, but there is no way to actually provide it any input because Sublime doesn't let you interact with a running program; it just lets you start it and wait for it to finish. As such, you're not getting any build time because the build goes on forever and never actually stops.
As a verification, note that the last thing that's presented in the output panel is the >>> prompt of the interactive interpreter, where it's waiting for input that you can't provide. Additionally the Tools > Cancel Build remains available, and selecting it terminates the build (although in this case is doesn't tell you how long it was running). That command is disabled if there's not a build running.
One way to fix your problem would be to remove the -i from your cmd entry above. Alternatively, you could use a version of the Python.sublime-build that ships with Sublime, modified to run python3 instead of python:
{
"shell_cmd": "python3 -u \"$file\"",
"file_regex": "^[ ]*File \"(...*?)\", line ([0-9]*)",
"selector": "source.python",
"env": {"PYTHONIOENCODING": "utf-8"},
"variants":
[
{
"name": "Syntax Check",
"shell_cmd": "python3 -m py_compile \"${file}\"",
}
]
}