[pjmlp]

This does not work if the GC updates the pointer concurrently.

[crawshaw]

The GC will not update a pointer once it is converted to the type uintptr. It becomes invisible to the precise collector, so the uintptr acts as an id value.

[pjmlp]

Worse, it might be collected then as the collector might think it is no longer in use.

[ianlancetaylor]

But it's in the map, so it's in use.

[pjmlp]

This remark is what triggered my comment

> It becomes invisible to the precise collector

So does the conversion to uintptr remove it from the root lists the GC searches?

[crawshaw]

It's a map[uintptr]unsafe.Pointer. The key is invisible to the collector, but the value is an unsafe.Pointer, which is will be managed for you by the precise collector.

[pjmlp]

Ah, stupid me! Thanks for clarifying it.