mod_rewrite.c has a TODO wrt always creating the rewrite lock global mutex which is only needed when rewritemaps (prg: only?) are used (IIUC). It would be nice to spare the added global mutex if it's simple.
Created attachment 35913 [details] Proposed patch for trunk
Created attachment 35915 [details] Proposed patch for trunk
This is fixed in trunk in r1831773.
Backported in 2.4.x in r1848681 This is part of 2.4.38