Provide the ability to turn off live error reporting in the new language server

[jiagengliu]

Environment data

• VS Code version: 1.25.1
• Extension version (available under the Extensions sidebar): 2018.7.1
• OS and version: Windows 10
• Python version (& distribution if applicable, e.g. Anaconda): Anaconda 5.1.0
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): conda
• Relevant/affected Python packages and their versions: Python

Actual behavior

After updating to 1.25.1, there are frequent messages (per second) of [Python (parser)] errors as I type a line. Is there a way to tell the Python parser to only parse upon save? I can't find the settings for parser in Settings.

Expected behavior

Only parse on save.

Steps to reproduce:

1. Open up test.py
2. Type a =

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

[Python (parser)] unexpected token '<newline>' (1, 5)"

[brettcannon]

@jiagengliu no setting, but we will think about adding this as a feature enhancement.

[brettcannon]

And another option is to put a timer on the trigger so that it only happens if you haven't typed in e.g. 5 seconds.

[MikhailArkhipov]

Generally this is normal behavior, happens in VS and other products as well as I type. We can throttle diagnostic output a bit and maybe add a setting for the delay.

The parser and code analysis is live and runs as you type. There is no option to get run just sometimes.

[DonJayamanne]

We can throttle diagnostic output a bit and maybe

I'd say that's what we should do, would also save CPU cycles.

I also feel 5secs is too long for reporting of syntax errors. Feels like forever, especially for novice developers using vscode to learn python.
Can I suggest 1-1.5s?
I feel 1s is also good even though the user has complained about the noise. It depends on how quickly users type as well. Would check other editors to come up with an optimal number.

[jiagengliu]

Is there an option to turn it off completely?

[MikhailArkhipov]

@jiagengliu - no.
@DonJayamanne - yes, it is going to be 1000 default. PR is up in PTVS. microsoft/PTVS#4612

Will add settings to VS Code then

[MikhailArkhipov]

Probably won't have much CPU since throttling is just delaying of the notification from LS to VSC. so if pending errors get cleared, they will never get reported. Some traffic save I guess.

[zooba]

Typically in VS we don't start processing text until you've stopped typing for 0.5-1s or you press Enter (and errors show up shortly afterwards). Not sure if we can do the same thing in Code...

[MikhailArkhipov]

Setting added via microsoft/PTVS#4612

[jiagengliu]

Thank you so much! @MikhailArkhipov