I've experienced a lot of issues that were the result of the nature of PHP living within the bounds of a stateless HTTP request, especially considering the asynchronous environment expected of modern web applications.
Namely, regeneration of session handles can cause session self-destructs if parallel requests are occurring. Additionally, unless a request locks the session for its duration, session updates on parallel requests are at risk of conflicting and being overwritten by the other. If they do lock the session, it forces serialization of the requests.
What did you find to be the most effective response to this problem?
Do you just live with it and implement workarounds? Did you ultimately migrate to a different platform that didn't have this flaw? Or is there a PHP solution to this problem I'm not aware of?