Documentation needs to specify that the import mode perforce user should have an "Unlimited" login timeout or large imports may fail.
Typical error is:
Caught exception on exit
com.perforce.p4java.exception.AccessException: Your session has expired, please login again.
at com.perforce.p4java.impl.mapbased.server.Server.handleErrorStr(Server.java:4907)
at com.perforce.p4java.impl.mapbased.server.Server.updateClient(Server.java:2519)
at com.perforce.p4java.impl.mapbased.client.Client.update(Client.java:465)