100% CPU usage for a long time after execution of the last statement

Version

v12.x-v20.x - severe, v8.x - v10.x - less severe but still visible

Platform

Darwin Andreys-MacBook-Pro.local 22.2.0 Darwin Kernel Version 22.2.0: Fri Nov 11 02:03:51 PST 2022; root:xnu-8792.61.2~4/RELEASE_ARM64_T6000 arm64

Subsystem

suspect GC

What steps will reproduce the bug?

run first script in the gist: https://gist.github.com/sidorares/128160e6b3dea1da3ad45cd672651d2d#file-repro1-js

After last line console.log("done"); is executed CPU spikes to 100% and stays like that for about 5 minutes.
In case of node v8 and v10 cpu spike is much shorter, 5-7 seconds.
Bun.js executes the script almost instantly

How often does it reproduce? Is there a required condition?

Consistently reproduceable

What is the expected behavior? Why is that the expected behavior?

the script is expected to finish in sub second time

What do you see instead?

CPU spikes for 300-400 seconds which is unexpected for the workload

Additional information

The profiler only reports the code before the CPU spike, no high GC usage, the time after cpu spike is "unaccounted".

 [Shared libraries]:
   ticks  total  nonlib   name
     98    0.0%          /Users/laplace/.nvm/versions/node/v20.3.0/bin/node

 [JavaScript]:
   ticks  total  nonlib   name
      2    0.0%    0.0%  JS: *parseLengthCodedInt /Users/laplace/tmp/2090/repro3.js:2014:24

 [C++]:
   ticks  total  nonlib   name

 [Summary]:
   ticks  total  nonlib   name
      2    0.0%    0.0%  JavaScript
      0    0.0%    0.0%  C++
     66    0.0%    0.0%  GC
     98    0.0%          Shared libraries
  291682  100.0%          Unaccounted

 [C++ entry points]:
   ticks    cpp   total   name

 [Bottom up (heavy) profile]:
  Note: percentage shows a share of a particular caller in the total
  amount of its parent calls.
  Callers occupying less than 1.0% are not shown.

   ticks parent  name
  291682  100.0%  UNKNOWN

まず、影響を受ける Node.js のバージョンでリンク先の gist にある最初のスクリプトを実行し、その動作を Node.js v8-v10 および Bun.js と比較します。報告された profiler の出力と再現時間を使って、console.log 後の CPU スパイクを調査します。スクリプトが持続的な CPU 使用なしに 1 秒未満で終了すれば完了です。