node only using half of the available memory

• Version: 12.19.0
• Platform: Debian Buster
• Subsystem:

What steps will reproduce the bug?

1. Start a container with limited memory (something like docker run --rm -it --memory=1G --memory-swap=1G node:12.19.0-buster-slim bash
2. Inspect heap size (node -e 'const v8 = require("v8"); console.log(v8.getHeapStatistics());')

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

100%

What is the expected behavior?

node would use all available memory

What do you see instead?

node is only using half of the memory, so we either need to give the container twice as much memory as we really want it to use (which is problematic) or also specify --max-old-space-size in addition to controlling the container which means we have to keep 2 different settings in sync and that's a big pain

Additional information

It appears that it was changed here, and only using half of memory makes sense when running on a system with multiple process, but when running in a docker container, using all of the memory allocated to the container makes more sense

首先，使用提供的 docker run 命令和 node -e v8.getHeapStatistics() 检查来复现问题。跟踪 Node.js 如何确定容器的内存限制，并将该值与预期的 1G 分配进行比较；完成的标准是运行时能够适当地设置堆大小，而不需要单独设置 --max-old-space-size。