The issue is as follows:
Because Transaction consumers are global for a graph. A SessionOpProcessor request will change the Transaction read write behavior to MANUAL across all concurrent/future requests.
This will make other requests fail (ones expecting AUTO).
This has been discussed here : http://mail-archives.apache.org/mod_mbox/incubator-tinkerpop-dev/201510.mbox/browser
The solution would be to make Transaction consumers ThreadLocal to keep the state local to the requests.
This is a breaking change.