In a few hours a patch will be going out which limits the number of concurrent searches a single user will be able to make to 5. This applies to logged in and anonymous users. The failure message is `You have too many concurrent searches running. If you are sharing an IP address with other users you can log in to get your own limits.` for anonymous users, or just `You have too many concurrent searches running.` for logged in users. These are the `cirrussearch-too-busy-for-you-anonymous-error` and `cirrussearch-too-busy-for-you-logged-in-error` i18n messages.
I will be monitoring the logs when this goes out, and intermittently throughout the week as well. If necessary we will whitelist certain ip ranges that seem to be shared among large numbers of users.
Erik B.