On 9/27/2018 8:00 AM, Shawn Heisey wrote:
On 9/27/2018 7:24 AM, Kimber, Mike wrote:
I'm trying to determine if there is any health check available to
determine the above and then if the issue happens then an automated
mechanism in SolrCloud to restart the instance. Or is this something
we have to code ourselves?
As shipped by the project, Solr will never restart itself
automatically. If it dies, it's dead until you start it again, unless
you implement something to restart it automatically.This is
intentional -- Solr almost never dies unless there's some kind of
problem -- not enough memory, corrupt software, etc.If Solr *does*
die, you need to figure out why and fix it, not rely on an automatic
restart.
Replying to myself. Probably a sign of insanity!
The other side of that coin is a completely unresponsive server. Here's
the thing about that situation: If it's really unresponsive, it
probably wouldn't be possible to send Solr a message to tell it to
restart itself. When a server in SolrCloud becomes unresponsive,
SolrCloud will attempt to have it do an index recovery, but this does
NOT involve a restart. Solr cannot restart itself automatically. It
might be possible to write that functionality into Solr, but I think
that using such functionality for automatic restarts on problem
detection is a very bad idea. The root of the problem must be found and
fixed, a restart probably isn't going to get rid of it.
If a SolrCloud server remains unresponsive, then any recovery operation
that is initiated is going to fail. Typically, problems that lead to an
unresponsive server are not the kind of problems that will go away
without action by the administrator -- adding memory, reducing the index
size, etc. If the admin restarts the server to clear that kind of
problem, it's very likely that the problem will happen again.
Thanks,
Shawn
