Delays when typing

This may only happen when typing quickly, but regardless, there's a delay when typing. See more info in #3518 (closed)

I previously reported that this is only happening in tmux, but that is not the case. It happens in plain iTerm tabs as well. I have noticed however that it only seems to happen in vim. Although I'm in vim the majority of the time so that may be why.

I have my key rate set up very high and I'm a very fast typist if that matters.

I certain cases it seems like it's taking a while to register the keystrokes and in other cases it's like the keystrokes "buffer" and then replay more slowly.

I believe based on my testing that the nightly on April 27th was the last good version without this bug, but it's intermittent so I can't guarantee that. I do know for a fact that it happens in the April 29th nightly. I'll continue to use the April 27th nightly and see if I can notice it there.

@gnachman is there anything else I can do to help you track this down?

BTW, the debug log on #3518 (closed) exhibited the problem at the very beginning of the capture.

If you turn off prefs>advanced>Terminal: Avoid repainting the screen when the cursor is hidden and restart, does that fix it?

@gnachman I've tried this for a few days with Terminal: Avoid repainting the screen when the cursor is hidden turned off and the strange behavior has not occurred at all.

Does that help track it down?

Looking at tha debug log, I see about .75 seconds of latency between when you type a key and when it gets echoed back. Either you're ssh'ed over a slow network or the performance problems in issue #3518 (closed) are interfering. Either way, it's hard to find what is probably 200ms of added latency due to this issue. Can you please make two new debug logs, one with and one without that setting turned on, ensuring that the bug reproduces when it's on.

Remember to restart after changing the setting.

Milestone changed to Ship 3.0

Reassigned to @gnachman

Assignee removed

@gnachman Ok so I think we have a slight bit of a problem. It turns out that, with Terminal: Avoid repainting the screen when the cursor is hidden set to Yes, the bug happens all the time. Getting an error report for it is np.

Unfortunately, when Terminal: Avoid repainting the screen when the cursor is hidden is set to No, the bug does not present itself (at least not that I can tell), however when Debug Logging is on, the typing is delayed just as much (if not worse) than when Terminal: Avoid repainting the screen when the cursor is hidden is set to Yes.

I have no idea what to do here, but I've attached a debug log for the most recent case when Terminal: Avoid repainting the screen when the cursor is hidden was set to Yes.

For this log, the delays were almost constant. Almost every keystroke resulted in a delay.

debuglog.tar.gz

@jfelchner can you make a screen cap video with Quicktime demonstrating the problem when Avoid repainting the screen is YES? It'll help me understand better what you're seeing.

@gnachman my apologies for taking so long on this. I had the workaround which let me get stuff done and duty called, but I wanted to make sure I didn't forget about this since you've been so awesome at responding and helping me out with other bugs.

Here's the link to the video. It's about a minute and it's tough to see exactly where the delays are happening. I put an overlay with my keystrokes so that you can see the difference between when I actually type and when it shows up on the screen.

https://www.dropbox.com/s/68o84fwvoce1rw4/iterm-delay-when-typing-bug.mp4?dl=1

Since it's tough to see, I'll call out a few of the major points where it happened:

• 0:28-0:30: you'll see a "jump"
• 0:44-0:47: if you go frame by frame, you can see that when I type "white" I can type the whole word before it shows up on the screen.
• 0:54-0:56: again frame by frame, you can see that typing "white" this time goes in fits and starts like it's buffering or something
• 0:59-1:01: This is the biggest lag that occurred during making this for you and is a common occurrence when using the terminal in normal usage

I hope this helps! Please ping me if you need anything else!

Thanks for the video, @jfelchner. Would you mind trying this build and let me know if it fixes the issue?

http://iterm2.com/adhocbuilds/iTerm2-2_9_20150701_204051-adhoc.zip

@gnachman I'm going to run this for a few more days, but my preliminary tests makes it seem like this has fixed the issue. :)

I'll comment back in a few days with a definitive answer.

@gnachman unfortunately this did not solve the issue :(

Do you need another debug log?

A debug log combined with a video would be really helpful. Please let me know exactly where the delay was visible to you so I can track it down in the debug log.

@gnachman here ya go. Since I think we both understand what the problem is, I just did a really short video to make it easier, but if you need more data, by all means, I'll be happy to provide it.

The lag happened most prominently, when I was typing "development". It's neither the best, nor worst lag I've experienced, but hopefully it'll be enough to give you a clue.

https://www.dropbox.com/s/1yif7vv5yccpsw0/iterm-delay-when-typing-bug-2.mov?dl=1 debuglog.tar.gz

What editor were you using? I see that procfile has something to do with Heroku. Is it possible that the data you were seeing on the screen came from the network?

I don't see that the missing letters were ever received by iTerm2, but I can't figure out how a local editor would drop them.

@gnachman I'm using vim. No it doesn't have anything to do with Heroku. It's all local. Just running through tmux.

It's also started happening now even with that flag set. Switching it back seems to make it worse but it's doing it regardless now.

I think the flag was a red herring. There might be something wonky going on with tmux. In fact, I'd bet anything it only happens in tmux.

Status changed to closed

@gnachman has this been resolved?

Can you confirm this only happens with tmux?

Also, please try the latest nightly build. There was a related issue which might have affected you.

Status changed to reopened

@gnachman I've been using nightly constantly and didn't notice that the option about repainting the screen had been removed.

This hasn't been happening to me so does that mean it's fixed?

Also yes, this only happened in tmux.

I think there are still bugs with that flag, but I made some changes to how redraws are timed when typing which might have improved this for you.

Status changed to closed