Generate a NodeJS Flamechart
Here’s how you can generate a Node flame graph with linux perf(1). Note that perf(1) needs to run as root, but the perf.map file node generates might be owned by a different user. If that’s the case, you’ll need to change its ownership to root as well — otherwise perf(1) will not be able to use it to translate JS stack frames.
$ uname -a
Linux demo 3.2.0-74-virtual #109-Ubuntu SMP Tue Dec 9 17:04:48 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
$ node --version
v10.16.0
$ node --perf-basic-prof-only-functions demo.js&
$ sudo perf record -F 99 -p `pgrep -n node` -g -- sleep 30
[ perf record: Woken up 3 times to write data ]
[ perf record: Captured and wrote 0.531 MB perf.data (~23181 samples) ]
$ ls /tmp/*.map
/tmp/perf-13083.map
$ sudo chown root /tmp/perf-13083.map
$ sudo perf script > nodestacks
Because we’re using perf-basic-prof-only-funcs, there are internal elided frames that are not mapped out, and manifest themselves as [unknown] frames, thus, we strip them out of the nodestacks output.
$ sed -i '/\[unknown\]/d' nodestacks
$ git clone --depth 1 https://github.com/sandeshdamkondwar/FlameGraph
$ cd FlameGraph
$ ./stackcollapse-perf.pl < ../nodestacks | ./flamegraph.pl --colors js > ../node-flamegraph.svg
This results in a flamegraph that looks like this:
One thing to note is that the –perf-basic-prof-only-functions flag results in a perf-