Piping into and out of the profiled binary

Question

Piping into and out of the profiled binary

walles opened this issue 4 years ago · comments

I want to profile this command line:

riff < /tmp/glp.txt > /dev/null

How can I do that using cargo instruments?

Riff is a filter that reads data from stdin and prints it to stdout.

If I just start riff using cargo instruments, ptop says that riff's stdin and stdout are both connected to instruments, which is not what I want.

How do I tell cargo instruments how to set up stdin and stdout for the profiled binary?

Colin Rofls · Answer 1 · Sat Nov 28 2020 01:13:15 GMT+0800 (China Standard Time)

I believe that instruments itself consumes stdin and stderr; you can verify this by running instruments directly and seeing if there's any way to get your binary's output? Assuming this is the case I don't know how to work around this. :(

Johan Walles · Answer 2 · Sat Nov 28 2020 01:36:20 GMT+0800 (China Standard Time)

I didn't get it working.

This I think should have worked, but it didn't:

xcrun xctrace record --template "Time Profiler" --target-stdin - --target-stdout - --launch -- target/debug/riff

Johan Walles · Answer 3 · Sat Nov 28 2020 01:38:37 GMT+0800 (China Standard Time)

What I did as a workaround BTW was:

start a full-system profile from the Instruments UI
run riff
after riff finished, press the stop button in the Instruments UI

Then scroll down to riff in the Instruments UI and see what happened.

Colin Rofls · Answer 4 · Sat Nov 28 2020 02:00:13 GMT+0800 (China Standard Time)

you should consider opening a radar with apple (or whatever the new version of radar is) in which case send me the number and I'll file a dupe.