The default maximum session limit (1500) can be changed by setting the following system property
liveview.max.sessions
We routinely bump this up when doing automated scale testing. It's clear if the server hits this limit because it reports every time another connection attempt is made when at the max with:
MAX_SESSIONS_EXCEEDED(28, "Max session ''{0}'' exceeded"),
A session comes from an individual connection, which is normally a single user. A session can have publishers and a configured maximum number of queries open on it. The default maximum number of queries usually isn’t a factor, as it defaults to 100. This can be changed by setting:
liveview.max.queries.per.session