FedX report error 503 Unavailable

[mhoangvslev]

Context

• FedX sends request to Virtuoso
• One of the threads failed and FedX cannot stop, causing engines to timeout.

[mhoangvslev]

Virtuoso sets up checkpoints every VIRT_Parameters_CheckpointInterval minutes. During the checkpointing, connections to clients are closed, hence the error 503. https://github.com/openlink/virtuoso-opensource/issues/1029

In our context, we use Virtuoso as a read-only database, therefore the checkpointing is not necessary