Example from cp1068 (sudo journalctl -u $service --since '1 hour ago'):
Nov 25 15:13:42 cp1068 varnishreqstats[24641]: Error in execute(): Log reacquired Nov 25 15:13:45 cp1068 varnishreqstats[24641]: Error in execute(): Log overrun Nov 25 15:13:45 cp1068 varnishreqstats[24641]: Error in execute(): Log reacquired Nov 25 15:13:47 cp1068 varnishreqstats[24641]: Error in execute(): Log overrun Nov 25 15:13:47 cp1068 varnishreqstats[24641]: Error in execute(): Log reacquired Nov 25 15:16:59 cp1068 varnishxcache[19844]: Error in execute(): Log reacquired Nov 25 15:17:02 cp1068 varnishxcache[19844]: Error in execute(): Log overrun Nov 25 15:17:02 cp1068 varnishxcache[19844]: Error in execute(): Log reacquired Nov 25 15:17:06 cp1068 varnishxcache[19844]: Error in execute(): Log overrun Nov 25 15:16:44 cp1068 varnishxcps[19840]: Error in execute(): Log reacquired Nov 25 15:16:47 cp1068 varnishxcps[19840]: Error in execute(): Log overrun Nov 25 15:16:48 cp1068 varnishxcps[19840]: Error in execute(): Log reacquired Nov 25 15:16:51 cp1068 varnishxcps[19840]: Error in execute(): Log overrun Nov 25 15:16:51 cp1068 varnishxcps[19840]: Error in execute(): Log reacquired Nov 25 15:16:55 cp1068 varnishxcps[19840]: Error in execute(): Log overrun
From https://info.varnish-software.com/blog/varnish-shared-memory-log-errors-and-solutions:
Cursor initialization failure: This error happens when varnishd is writing to the Shared Memory Log faster then the program that is trying to read from it. Since the VSL is a circular buffer Varnish can overrun it and if it happens, the program reading the VSL will end up with inconsistent data. To be honest I’ve never seen anyone affected by this issue, but the solution would be to have a persistent VSL so the slow program accessing it will have enough time to read it with consistency.
Varnish code major suspects:
https://github.com/varnishcache/varnish-cache/blob/4.1/lib/libvarnishapi/vsl_cursor.c#L130
https://github.com/varnishcache/varnish-cache/blob/4.1/lib/libvarnishapi/vsl_cursor.c#L201