On all text@esams hosts, varnish-frontend-fetcherr is currently using 100% of one CPU core. There's this in the journal:
May 11 20:12:35 cp3058 varnish-frontend-fetcherr[26530]: Assert error in vslc_vtx_next(), vsl_dispatch.c line 285: May 11 20:12:35 cp3058 varnish-frontend-fetcherr[26530]: Condition(c->offset <= c->vtx->len) not true.
That looks like output from varnishlog, which is executed by BaseVarnishLogConsumer. We likely need to add some sort of error handling to main().