browser list used for invokeVisualizer needs be rethought

[hyangah]

pprof invokes web browsers when the output of the command (e.g. web or weblist) needs to be visualized in a web browser.

golang/go#25853 exhibited a couple of issues around the browser invocation logic.

1. the list of browsers populated in browsers needs to be rethought.

If there is BROWSER env var set, I think it should be picked as the first choice. Currently, not. FYI, go's cmd/internal/browser package has an implementation for the similar purpose.

Also, note that commands like chrome or google-chrome are not used on Mac. If they exist, they are likely not the browser command we expect.

2. invokeVisualize returns once the command binary is located and can launch a process.

The command's stderr is directed to the pprof's stderr so users could be able to see the error message but only if the command outputs the error message to stderr. I don't know what's the best way to deal with it. Will it be useful if the tool prints out the exact command? Or, wait for a second, and if the process seems to exit with error code already, try again?

[marwan-at-work]

Thanks for opening this issue!

I think it might be helpful if the web and weblist commands communicated a little more to the user about what they did. So that if there's some weird behavior, the user can probably figure it out quickly.

I was unfamiliar with pprof and how the web command worked internally. And so typing web and seeing it break, was intimidating and confusing until 4-5 hours later.

So maybe when you type web the following will be logged:

attempting to find chrome binary
chrome binary not found.
attempting to open Firefox through firefox binary

etc etc

When chrome actually opened for me, but it didn't work, I thought there was some fundamental problem, and not that I just had the wrong binary. I was able to tell because the which chrome command gave me a suspicious path.

Maybe more robustly, if an OS had a consistent way of opening a user's default browser, then that would probably be best.

[nolanmar511]

First part (changing the order of browsers) is fixed with #392.

[nolanmar511]

Updatinge here #392 was rolled back to fix #402 (using "xdg-open" as the default resulted in pprof- web opening the graph in the default SVG viewer; tooltips and panning do not necessarily work when opening the graph using the default SVG viewer).

[elichai]

Maybe we should get rid of the svg and replace it with an html file? (embedded JS in svg is a little weird) that way we can just use xdg-open as default