Browser gets frozen when a command outputs too much data

[crevete]

When we type a command that outputs too much (or unlimited) data, for example find /proc or yes, the browser (Firefox, even Chrome) will be very slow or gets frozen. This performance issue is due to the algorithm you use when rendering output on screen : you first write the entire data into a buffer and then you display it. This means : the data is read twice.

I know this is not quite simple, but I wonder is it possible to do better to get higher performance so that the browser will not get frozen at least.

[crevete]

Any input on this performance issue @chjj , thanks ?

[chjj]

I've personally never run into this. I just tested it in my terminal (as a blessed widget, which could conceivably have even worse performance issues especially if the terminal is not full screen). I ran yes, find /, and cmatrix and noticed no performance issues. I'll have to test it in the browser.

I've tried to optimize the browser renderer a number of times in the past. I always ended up scrapping it due to its complexity and headaches. I've never heard of it actually freezing though (the freezing might be a different issue, it should never freeze completely just because it takes a while to render something).

[aurium]

@chjj i also believe the bug is not related to data stream size. Wherever, if i get it right, term.js remove all child html elements from the terminal element and writes new ones for every update. That is surely not the best approach. :-) Did you think about to have one <span> for each screen position and update only the innerText with the right char and the style attribute with the local term style?

[crevete]

@aurium Personally I think it would be better.
@chjj Actually what I mean "frozen" is just like you said : it takes long time to render something, and that may give impression that the browser is frozen. And when it outputs, for example find /proc, and I hit Ctrl+Cto stop it, it may fail (It continues to output results). That's we have experienced after tens of tests.

[sagar-chandarana]

try 'yes blah'. it will freeze, at least it did for my whole team and customers. In my implementation, i managed to hack it with a buffer, and a rate of data bursts, so that browser has only a few things to render at a time. when the buffers got filled, i had to remove the characters yet to be sent, and that sometimes distorts things for graphic heavy apps

[crevete]

@sagarchandarana123 thanks to confirm this issue. Could you share your workaround source code ?

[sagar-chandarana]

@crevete https://github.com/bitfusionio/term.js-implementation