Issue #19443 has been updated by byroot (Jean Boussier). Relaying here what Javier Honduvilla Coto said on one of the PRs:
wondering if it would be possible/make sense to override libc's getpid with a custom implementation that does the caching in there. That way not only Process.getpid would use the faster method but also any other part of the runtime such as what @dalehamel mentioned above or any other getpid calls from native libraries?
I don't know if it's a good idea or not, as far as I know it would be a first for ruby to override a symbol defined by libc, it doesn't do so with `malloc` and `free` for instance. ---------------------------------------- Feature #19443: Cache `Process.pid` https://bugs.ruby-lang.org/issues/19443#change-102203 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal ---------------------------------------- It's not uncommon for database client and similar network libraries to protect themselves from Process.fork by regularly checking Process.pid Until recently most libc would cache `getpid()` so this was a cheap check to make. However as of glibc version 2.25 the PID cache is removed and calls to `getpid()` always invoke the actual system call which significantly degrades the performance of existing applications. The reason glibc removed the cache is that some libraries were bypassing `fork(2)` by issuing system calls themselves, causing stale cache issues. That isn't a concern for Ruby as bypassing MRI's primitive for forking would render the VM unusable, so we can safely cache the PID. An example of the issue: https://github.com/rails/rails/issues/47418 Patch: https://github.com/ruby/ruby/pull/7326 -- https://bugs.ruby-lang.org/