Improve xterm.js performance

[Tyriar]

There are a few improvements needed in xterm.js to improve terminal performance

• Use circular list to manage buffer PR: Use a circular list to manage buffer xtermjs/xterm.js#422
  • Also fixes scrollback issue scrollback doesn't work as expected xtermjs/xterm.js#361
• Proposal: revamp the refresh method for better rendering performance Proposal: revamp the refresh method for better rendering performance xtermjs/xterm.js#150 (no longer needed with other changes)
• Performance of refresh is still subpar Performance of refresh is still subpar xtermjs/xterm.js#134 (no longer an issue)
• Viewport.refresh seems to be triggered on every line of input Viewport.refresh seems to be triggered on every line of input xtermjs/xterm.js#290 (PR: Improve refresh queue xtermjs/xterm.js#438)
• Refresh limit system makes performance bad on Windows Refresh limit system makes performance bad on Windows xtermjs/xterm.js#280 (PR: Improve refresh queue xtermjs/xterm.js#438)
• Commands that fill a non-full buffer lock up the terminal for a couple of seconds Commands that fill a non-full buffer lock up the terminal for a couple of seconds xtermjs/xterm.js#444 (PR: Rate limit Viewport.refresh xtermjs/xterm.js#445)
• Reconsider XON/XOFF PR to keep slave in sync with terminal Reconsider XON/XOFF PR to keep slave in sync with terminal xtermjs/xterm.js#425 (PR: Sync with pty process using XOFF and XON xtermjs/xterm.js#447)
• Too much time is spent in getBoundingClientRect (no issue) (PR: Style wide characters at charWidth*2 in DOM xtermjs/xterm.js#440)
• Investigate reuse of DOM nodes to reduce browser garbage collection Investigate reuse of DOM nodes to reduce browser garbage collection xtermjs/xterm.js#449 (PR: Keep row spans in an object pool to reduce garbage collection by reusing DOM nodes xtermjs/xterm.js#450) Deferred until results are proven or the model is needed for something else
• 💪 Optimize parser Pull parser into its own class and improve performance xtermjs/xterm.js#459 (PR: Parser refactor and optimization xtermjs/xterm.js#462)

[nirmaljpatel]

I am using VSCode as IDE for Appcelerator App development. I compile and run the project using a Grunt build task which in turn uses grunt-shell to invoke a CLI command: appc run.
The output is directed to console. If I turn on high level of logs output, the terminal process stops with following error msg:

Warning: stderr maxBuffer exceeded Use --force to continue.
Aborted due to warnings.
Execution Time (2017-01-27 16:00:19 UTC-6)
loading tasks       902ms  ▇ 2%
shell:appc-run-sim  43.2s  ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 98%

The expectation would be the console should keep running showing the messages directed at it.
I tried specifying maxBuffer to the shell command (via grunt). This did increase the amount of logs before this error appeared. When set to 20MB, the entire Code IDE froze.

[Tyriar]

@nirmaljpatel what version are you on?

[nirmaljpatel]

Code Version 1.8.1 (1.8.1)
MacOS Sierra (10.12.2)

[Tyriar]

@nirmaljpatel next version January/1.9.0 fixes the performance issues. You can try it out now with https://code.visualstudio.com/insiders

[nirmaljpatel]

On this newer version, I still faced the same issue.

Warning: stderr maxBuffer exceeded Use --force to continue.
Aborted due to warnings.
Execution Time (2017-01-27 16:08:30 UTC-6)
loading tasks       565ms  ▇ 2%
shell:appc-run-sim  29.9s  ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 98%
Total 30.5s

However, after specifying the maxBuffer for grunt-shell, the output is running fine so far.

execOptions: {
	maxBuffer: 1000 * 1000 * 10
}

[Tyriar]

Sounds like an issue with grunt-shell?