Workflow eviction implemented via parallel execution handler, accompanied by a dedicated telemetry event handler to monitor eviction related events.

This sample is a variation of the "Workflow Eviction" sample. Workflow eviction is managed here by a dedicated parallel execution handler, eviction_handler/2, which processes consecutive Temporal events and invokes the evict_workflow/0 SDK command to evict workflow. If a Temporal history event includes a history_size_bytes field in a WorkflowTaskStartedEvent, the eviction logic is applied according to the specified eviction strategy. Eviction requests in this sample are known in advance of the gRPC RespondWorkflowTaskCompletedRequest call, enabling SDK to avoid polling stale workflow tasks from the sticky queue.

Example run:

Elixir

iex(1)> EvictionParallelHandler.run(70_000, :custom)
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
:ok
iex(2)> EvictionParallelHandler.run(100_000, :custom)
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 51 -> evicted
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
:ok
iex(3)> EvictionParallelHandler.run(500_000, :custom)
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 9 -> evicted
[temporal_sdk,workflow,executor,stop]: 15 -> evicted
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 51 -> evicted
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
:ok
iex(4)> EvictionParallelHandler.run(1_000, :always)
[temporal_sdk,workflow,executor,stop]: 3 -> evicted
[temporal_sdk,workflow,executor,stop]: 9 -> evicted
[temporal_sdk,workflow,executor,stop]: 15 -> evicted
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 51 -> evicted
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
:ok
iex(5)> EvictionParallelHandler.run(1_000, :never)
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 63 -> completed
:ok

Sample source: lib/eviction_parallel_handler

Erlang

1> eviction_parallel_handler:run(70_000, custom).
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
ok
2> eviction_parallel_handler:run(100_000, custom).
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 51 -> evicted
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
ok
3> eviction_parallel_handler:run(500_000, custom).
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 9 -> evicted
[temporal_sdk,workflow,executor,stop]: 15 -> evicted
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 51 -> evicted
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
ok
4> eviction_parallel_handler:run(1_000, always).
[temporal_sdk,workflow,executor,stop]: 3 -> evicted
[temporal_sdk,workflow,executor,stop]: 9 -> evicted
[temporal_sdk,workflow,executor,stop]: 15 -> evicted
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 51 -> evicted
[temporal_sdk,workflow,executor,stop]: 57 -> evicted
[temporal_sdk,workflow,executor,stop]: 63 -> completed
ok
5> eviction_parallel_handler:run(1_000, never).
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 21 -> evicted
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,poller,execute,stop]: sticky_hit
[temporal_sdk,workflow,executor,stop]: 63 -> completed
ok

Sample source: src/eviction_parallel_handler