Dylan DPC 354f19cf24
Rollup merge of #81850 - the8472:env-rwlock, r=m-ou-se
use RWlock when accessing os::env

Multiple threads modifying the current process environment is fairly uncommon. Optimize for the more common read case.

r? ````@m-ou-se````
2021-02-12 22:53:33 +01:00
..
2020-12-07 15:22:34 +01:00
2020-11-22 17:11:41 -05:00
2021-01-07 16:16:36 +09:00