I am trying to understand the cause of the problem we have been plaguing our environment. It has to do with writing attributes to configuration element. A bit of background first. We utilize config element as a sort of reference table for workflows that take VM name as an input parameter. In a grand deployment scheme we search for target VM once, populate config element with the attribute reference for VM entry as an object, and then any subsequent workflows will use that config reference where we need an object instead of an incoming VM name string.
This works fairly well for us but once in awhile attributes are missing from the config. We can see in the even log for the config element that it was saved during write attempt but not all expected entries are present. We have tried to use locking mechanism during write calls to rule out race condition, as well we padding adding couple of seconds of sleep after setting the attribute, no dice.
I am still fairly certain that this occurs when two or more write attempts are executed in parallel. I put together a simple mock up of how to reproduce this issue and was hoping to get some feedback for improvement or perhaps a suggestion for another way of doing fast object lookups (vCD or VC).
- Package contains 5 workflows and a config element.
- Config element "write test" has two attributes, populate them with VC:VirtualMachine objects (two or three unique entries per set should be enough).
- Execute workflow "config write test" with boolean set to yes; expect for config "write test" to be populated with however many objects were referenced in each set (all should be there).
- Execute workflow "config write test" with boolean set to no; expect all VM name attributes to be removed from the config "write test".
Running this test in my tiny lab environment exhibits this problem fairly frequently (vro7.0.1 appliance with local postgres). Either on add or delete, only one set is written, yet event log says that element is being saved on each entry.