We are deploying multiple VM's(around 30) in vCenter using API calls. At certain scenarios, the vm's being deployed are getting stuck and further on no operations can be carried out on the vCenter. We have to restart the vCenter in this case and post that, things are returning back to normal, however the explained problem is intermittent at times. Please let us know what is causing this problem and what can be done to prevent this
Are you getting any pertinent errors in the logs? It sounds like your vCenter is being overwhelmed but, beyond that, it could be any number of things causing your intermittent issues.