Hi, When sending updates to Solr, you often need to run multi threaded to utilize the CPU on the solr side. But how can the client (whether it is pure HTTP POST or SolrJ know whether Solr is happy with the indexing speed or not?
I'm thinking of a feedback mechanism where Solr can check its load level, indexing queue filling rate or other metrics as desired, and respond to the caller with a HTTP 503, or a custom Solr HTTP code "533 Slow down". Clients will then know that they should pause for a while and retry. Clients can then implement an exponential backoff strategy to adjust their indexing rate. A bonus with such a system would be that Solr could "tell" indexing to slow down during periods with heavy query traffic, background merge activity, recovery, replication, if warming is too slow (max warming searchers) etc etc. I know Elastic has something similar. Is there already something in our APIs that I don't know about? Jan
