RFR: JDK-8301749: Tracking malloc pooled memory size [v3]

[Johan Sjölen]

On Wed, 8 Feb 2023 13:25:15 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> > > return -1.
> > > You aim to mimic the malloc_info() API at os:: level, so you should return -1 in case malloc_info failed, including failure do to resolving issues.
> > 
> > 
> > Wouldn't that lead to a caller not knowing whether `malloc_info` itself failed or if our wrapper failed?
> 
> Why would that matter?
> 
This matters when a caller sees -1, reads errno, and then takes an action depending on errno. If it was our wrapper that failed, then this will be a "stale" errno and a faulty action will be taken. This matters in `MallocInfoDcmd::execute` because we send different error messages depending on whether the wrapper failed or `malloc_info(3)` failed.

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PR: https://git.openjdk.org/jdk/pull/12455