We are experiencing bad gaps in performance, where the ES machine
stops responding for half a minute, consuming all CPUs completely.
We narrowed the problem down to field caches. There seems to be no
problem with free RAM, but despite that, the field cache sometimes
gets invalidated (bigdesk suddenly reports 0B field cache). This leads
to field cache loading -- several GB -- which takes a lot of time and
is the cause of the GC freeze.
Question: under what conditions is the field cache invalidated?
Is there any way to invalidate only a part of it (one segment?)
instead of this mega-freeze + sudden loading from zero to several GB?
Is there a way to pre-load the field cache as soon as possible, and
not wait for user queries? Would setting "soft" cache type help?