uvm_task_phase

Base class for all task phases.  It forks a call to <uvm_phase::exec_task()> for each component in the hierarchy.

The completion of the task does not imply, nor is it required for, the end of phase.  Once the phase completes, any remaining forked <uvm_phase::exec_task()> threads are forcibly and immediately killed.

By default, the way for a task phase to extend over time is if there is at least one component that raises an objection.

class my_comp extends uvm_component;
   task main_phase(uvm_phase phase);
      phase.raise_objection(this, "Applying stimulus")
      ...
      phase.drop_objection(this, "Applied enough stimulus")
   endtask
endclass

There is however one scenario wherein time advances within a task-based phase without any objections to the phase being raised.  If two (or more) phases share a common successor, such as the <uvm_run_phase> and the <uvm_post_shutdown_phase> sharing the <uvm_extract_phase> as a successor, then phase advancement is delayed until all predecessors of the common successor are ready to proceed.  Because of this, it is possible for time to advance between uvm_component::phase_started and uvm_component::phase_ended of a task phase without any participants in the phase raising an objection.