iTerm2 3.1.beta6 feels jumpy vs 3.0.15 (with comparison video)

• iTerm2 version:

3.1.beta6 and 3.0.15

• OS version:

macOS 10.12.6

• What happened:

3.1.beta6 (other betas too) have felt jumpy. I made recordings comparing the versions of just leaving "enter" pressed at my prompt, slowed down to 4%.

In 3.1.beta6, notice that we go to next line and wait, before the prompt is drawn. And sometimes, only half of the next prompt is drawn before the other half comes in (example @ 13s). In 3.0.15, it's completely smooth. So smooth, that I had to add additional text in the video to act as a reference point, otherwise, you couldn't tell it was moving.

I've emphasized "feels" because I've seen threads of improved latency performance, and maybe the jumpiness is in fact the result of faster drawing.

I know there's not much to go on this issue, but just wanted to bring it up since the videos confirm that there is at least a difference between 3.1.beta6 and 3.0.15.

iTerm2-3_1_beta_6

iTerm2-3_0_15

Faster latency without very fast drawing can cause this kind of effect. Could you provide a debug log? I need to see the specific timings, since this doesn't happen on my system. Maybe I can add a strategic delay somewhere.

Thanks! Here are logs for both versions while I re-did the same thing as in the videos.

debuglog-3_0_15.txt

debuglog-3_1_beta6.txt

Please try this build:

http://iterm2.com/adhocbuilds/iTerm2-3_1_20170801_221757-adhoc.zip

It tweaks when the frame rate changes to avoid entering adaptive framerate mode too early.

changed milestone to %Next Beta

Note to self: this is in the cadenceControllerAndDeferredCadenceChanges branch

Thanks! It's better, but the half prompt still happens sometimes. This is a video with of your new build. After most return presses, it doesn't happen, but for some it does.

iTerm2-3_1_20170801_221757-adhoc

Btw, I'm able to repro this on my personal and work computer (my unixname is asuarez if you want to ping me directly).

@zertosh Please send a debug log using the adhoc build that reproduces the issue.

@gnachmandebuglog.txt

There was a silly bug. Please try this build and let me know if it's better:

http://iterm2.com/adhocbuilds/iTerm2-3_1_20170820_220120-adhoc.zip

Note to self: this is in the deferredUpdateWithBugfix branch.

Feels much better, but if I leave "enter" pressed, it happens every other seconds, whereas with v3.0.15, it never happens. Now for iTerm2-3_1_20170820_220120-adhoc.zip: debuglog.txt

What I see in the log is that every once in a while the screen is drawn when the cursor is on the line below the $ prompt. This seems to be a random occurrence and basically just unfortunate timing.

closed

The smarter cadence algorithm is now in master in commit 9077b924.

Thanks for looking into it! I <3 iTerm!