When running export on large database runs into a dead lock situation

[makpcheng]

Version: Janusgraph 0.2.0

Steps:
Export graphml on a large database, one larger than 2GB in size. Somewhere in between it will deadlock when writing out vertex objects and their properties. There appears to be a deadlock when querying for properties.

Workaround:
Add lots of debug statements to slow the export down enough to prevent the deadlock from happening.

[porunov]

It could be related to BerkleyDB issues but I didn't research it much. In case you used BerkleyDB as a storage backend, the next configuration may help in some situations:

storage.berkeleyje.lock-mode: LockMode.READ_UNCOMMITTED

That said, I also have seen many cases with lock acquittance timeout issues when a storage backend can't perform operations in a necessary time frame. I don't think this is directly connected to this problem, but the below configuration can help with timeouts:

storage.lock.wait-time: 5000