Hi
Do you see a log line that relates to which type of "Scheduler" you are using such as:
[notice] Scheduler type KIST has been enabled.
It's Freebsd: [notice] Scheduler type KISTLite has been enabled.
It is seriously a huge amount of circuit and very little data. For isntance 13344 bytes that is 0.013 MB for 594572 circuits is just weird.
Is there a chance you are being DoS in some capacity? That is bunch of circuits being opened constantly but with no traffic? You would see that with many inbound connections and if they come from non relays also.
This happens every some weeks to different relays. Inbound connections are on a normal level. I believe some client(?) tries a DoS type of circuit exhaustion, at least it seems. The number of circuits goes up to over a million. If it goes with much memory consumption the remove/killing comes along.
Another possibility is that Tor is failing to cleanup inactive circuits but with more information, we can eliminate options more easily.
What can I do ? The relay is still on with 3.4 GB. But circuits are pretty relaxed since five hours.