[Feature Request] Show Progress

[lixin-wei]

In my case, perf.data is huge(10GB+) and usually takes 30+ min to generate the flame graph.

It will be much more friendly if there is a progress bar.

[djc]

Unfortunately I don't have much time for maintaining flamegraph. Maybe consider submitting a PR?

[lixin-wei]

Is there any doc about the overall structure/execution path of this project? I'm willing to have a try but don't know where to start.

[djc]

No, but it's pretty simple. We get the inferno crate to collapse the data at https://github.com/flamegraph-rs/flamegraph/blob/main/src/lib.rs#L367 and generate the flamegraph at https://github.com/flamegraph-rs/flamegraph/blob/main/src/lib.rs#L427. You should figure which of those is slow. Then, I think you might want to wrap an indicatif thing around the input to either of those things (or both?).

[smoelius]

@djc Do these look like the right links? I'm speculating based on the date of your comment:

• flamegraph/src/lib.rs

  Line 367 in 1aeb2a8

  Folder::from(collapse_options)

• flamegraph/src/lib.rs

  Line 427 in 1aeb2a8

  from_reader(&mut inferno_opts, collapsed_reader, flamegraph_writer)

[smoelius]

Also, for me, the bottleneck appears to be perf script:

flamegraph/src/lib.rs

Line 128 in 1aeb2a8

let output = command.output().context("unable to call perf script")?;

Is this surprising to you? (I don't know what this command does.)

[djc]

Unless you've specifically enabled --post-process I think you'll want to ignore the if let Some(_) = opts.post_process { .. } block, so I think you'd want to look at the Folder::from(..).collapse(..) block currently around line 395 and the from_reader() call currently around line 455.

I don't know much about perf script, either -- I'm really just here to review/merge PRs that seem correct but otherwise know about as much as a typical user about the inner workings of perf.

If it doesn't work well for you, consider trying samply instead -- it seems to work better on macOS at least, and @mstange is a lot more knowledgeable about perf stuff and profiling in general.

[gth828r]

This is a problem which I had, so I can probably take a stab at adding this feature. Implementing a true progress bar with perf script is not obvious to me, but I think a spinner with a message about what is running and an elapsed time is a good start, and that is fairly simple to add.

[gth828r]

Ok, after a few different iterations, I found something that I like and it is available as a PR at #343