Empty cache file can cause pipeline to fail without log notices

[kliegr]

This behaviour can be reproduced

• load attached task.json.
• create empty file "rulesPCA" in the workspace
• run the pipeline

What will happen:
Indexing will not start. The log messages shown are:

2020-09-11 14:55:25:461 +0200 [rdfrules-http-akka.actor.default-dispatcher-6] INFO com.github.propi.rdfrules.http.InMemoryCache - Some value with key '025495e4-8e84-4f30-bfec-325a18dd3499x' was pushed into the memory cache. Number of items in the cache is: 1
2020-09-11 14:56:16:359 +0200 [Thread-1] INFO task-7216ee1d-9a9b-4286-bad1-0425e3c6b6fc - Predicates trimming.
2020-09-11 14:56:16:363 +0200 [rdfrules-http-akka.actor.default-dispatcher-9] INFO akka.actor.LocalActorRef - Message [com.github.propi.rdfrules.http.service.Task$TaskRequest$AddMsg] to Actor[akka://rdfrules-http/user/task-service/task-7216ee1d-9a9b-4286-bad1-0425e3c6b6fc#-1209497236] was not delivered. [1] dead letters encountered. If this is not an expected behavior then Actor[akka://rdfrules-http/user/task-service/task-7216ee1d-9a9b-4286-bad1-0425e3c6b6fc#-1209497236] may have terminated unexpectedly. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.

A workaround is either to delete the empty cache file "rulesPCA" or to set the last Cache node in the pipeline to "revalidate" the cache.

task.json.zip