Because ZFS may consume large amounts of RAM to cache various types of filesystem objects, it continuously monitors system RAM available to decide whether to shrink its caches. Some caches are shrunk using a dedicated thread, to which work is dispatched asynchronously.
In some cases, the cache shrinking logic may dispatch excessive amounts of work to the "ARC pruning" thread, causing it to continue attempting to shrink caches even after resource shortages are resolved.
