using getExecutor() when threadManager_ is null
using getExecutor() when threadManager_ is null

Summary:
^

(Note: this ignores all push blocking failures!)

Reviewed By: roddym

Differential Revision: D34906283

fbshipit-source-id: f3d72a59942f3f95574902a858f6d5c9b2fafa94

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift