On 8/7/20 4:39 PM, David Lloyd wrote: > However, I'm wondering if this isn't a side effect of what appears > to be an incorrect double-checked lock at lines 374-378 of > ClassValue.java [1]. In order for the write to the non-volatile > `cache` field of ClassValueMap, it is my understanding that there > must be some acquire/release edge from where the variable is > published to guarantee that all of the writes are visible to the > read site, and I'm not really sure that the exit-the-constructor > edge is going to match up with with the synchronized block which > protects a different non-volatile field. And even if my feeling > that this is dodgy is valid, I'm not sure whether this NPE is a > possible outcome of that problem!
It certainly doesn't look right to me. AFAICS this is classic broken double-checked locking. It'd need some sort of fence after constructing the ClassValueMap instance and before publishing it. -- Andrew Haley (he/him) Java Platform Lead Engineer Red Hat UK Ltd. <https://www.redhat.com> https://keybase.io/andrewhaley EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671
