History Service - caching

Current Stuation

• The History Service uses a caching mechanism to reduce database transactions.
• The History Service creates its own cache objects based on the following JS7 objects:
  • Workflows
    • each workflow used is added to the cache and remains in the cache.
  • Orders
    • an order and possible child orders (Fork/Join Instruction) are added to the cache and are removed when an order is terminated (OrderCancelled, OrderFinished, OrderBroken).
      • orders that are not completed and are e.g. in a failed, suspended state, remain in the cache:
      • child orders (Fork instruction) are not removed from the cache, which can cause an OutOfMemory exception.
  • Order Steps/Jobs

Desired Behavior

• The History Service should have a robust caching mechanism.
• In addition to the correct add/remove operations from the History Cache, the History Service should start a routine every hour to clean up cached Workflows/Orders/Order Steps that are still present but no longer in use (garbage collection).

Test Instructions

• Create and start a workflow (use Fork/Join Instruction)
• Check the logs/service-history.log file and look for [cached workflows=<n>,orders=<n>,steps=<n>] at the end of each history line
  • Expected result:
    • Finished/Cancelled/Broken Orders with all child orders and steps should be removed from the History Cache immediately.
    • Failed/Suspended Orders and Workflows should be removed after 1 hour