Manual:$wgClockSkewFudge

Cache: $wgClockSkewFudge
Fudge time to add to cache timestamps to adjust for clock skew.
Introduced in version:1.4.6 (r9403)
Removed in version:1.33.0 (Gerrit change 496694; git #074ce9ab)
Allowed values:(number of seconds (integer))
Default value:5

Details edit

Clock skew or the one-second resolution of time() can occasionally cause cache problems when the user requests two pages within a short period of time. This variable adds a given number of seconds to vulnerable timestamps, thereby giving a grace period.