Re: Unnecessary connection overhead due copy-on-write (mainly openssl)

On 05.06.25 21:58, Andres Freund wrote:
> The reason for this difference is that by default openssl registers an atexit
> handler that frees a lot of memory that was initialized in postmaster. That in
> turn triggers page-faults due to the relevant pages now differing in child
> processes. Which a) isn't cheap b) causes contention with postmaster, since
> those datastructures are shared.
>
>
> It's possible to tell openssl to not register an atexit handler, see [2]:
>
>> OPENSSL_INIT_NO_ATEXIT
>> By default OpenSSL will attempt to clean itself up when the process exits via
>> an "atexit" handler. Using this option suppresses that behaviour. This means
>> that the application will have to clean up OpenSSL explicitly using
>> OPENSSL_cleanup().

It seems weird to me that openssl spends so much effort tidying up its
memory allocations just before exiting. We could just skip that.
Looking through the code of OPENSSL_cleanup(), there might be one or two
cases of log or trace files that get flushed during cleanup, so it's not
an absolute no-brainer to skip all the cleanup.