Question about uv_get_available_memory API

[theanarkh]

The value of uv_get_available_memory is equal to limit_in_bytes - usage_in_bytes, but the value of usage_in_bytes includes RSS and Page Cache. So i think the available memory should equal to limit_in_bytes - RSS instead of limit_in_bytes - usage_in_bytes ?

[bnoordhuis]

I don't really understand what you're asking. If you're saying libuv is doing something wrong, please motivate why.

[vtjnash]

I think it is a reference to #3897, but I am increasingly uncertain that is better than the (also fairly useless) status quo.

[theanarkh]

Thanks !

[theanarkh]

I want to know how much memory the process can use before OOM.

[bnoordhuis]

On general-purpose multitasking operating systems that's fundamentally unknowable. uv_get_available_memory() is an educated guess, useful for diagnostics but not for policy. Reasons why:

• the system's available resources may have changed by the time the function returns
• your process may not be able or is not allowed to allocate that much memory
• your process can allocate way more due to overcommit or (possibly compressed) swap

If you're trying to write software that's robust in low memory situations, then your best best is to disable overcommit and always handle allocation failures, but even that may not always stave off the OOM killer.

[theanarkh]

Thanks for the clarification.

[theanarkh]

@bnoordhuis If there are two processes in the container.
limit_in_bytes indicates memory of process1 + memory of process2 cannot exceed the limit_in_bytes limit ?
usage_in_bytes Indicates that memory of process1 + memory of process2 is equal to usage_in_bytes ?

[bnoordhuis]

Yes, I believe that's correct.

[theanarkh]

Thanks !