DEV: fix hanging spec (#29974)

lib/scheduler/defer.rb

@@ -76,6 +76,7 @@ module Scheduler
     def stop!(finish_work: false)
       if finish_work
         @finish = true
+        @queue.push({ finish: true }, force: true)
         @thread&.join
       end
       @thread.kill if @thread&.alive?
@@ -108,7 +109,9 @@ module Scheduler
 
     # using non_block to match Ruby #deq
     def do_work(non_block = false)
-      db, job, desc = @queue.shift(block: !non_block).values_at(:db, :job, :desc)
+      db, job, desc, finish = @queue.shift(block: !non_block).values_at(:db, :job, :desc, :finish)
+
+      return if finish
 
       start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
       db ||= RailsMultisite::ConnectionManagement::DEFAULT

spec/lib/scheduler/defer_spec.rb

@@ -22,6 +22,12 @@ RSpec.describe Scheduler::Defer do
     Discourse.reset_catch_job_exceptions!
   end
 
+  it "can finish work properly without crashing" do
+    @defer.later {}
+    sleep 0.005
+    @defer.stop!(finish_work: true)
+  end
+
   it "supports basic instrumentation" do
     @defer.later("first") {}
     @defer.later("first") {}