Stop report workers when parent times out

No need to keep running when nobody is collecting the result (yet).

app/services/job_processor.rb

@@ -3,9 +3,16 @@
 # Forks into a separate process to contain memory usage and timeout errors.
 class JobProcessor
   def self.perform_forked(job, *args)
-    fork do
+    # Reports should abort when puma threads are killed to avoid wasting
+    # resources. Nobody would be collecting the result. We still need to
+    # implement a way to email or download reports later.
+    timeout = ENV.fetch("RACK_TIMEOUT_WAIT_TIMEOUT", "30").to_i
+
+    child = fork do
       Process.setproctitle("Job worker #{job.job_id}")
-      job.perform(*args)
+      Timeout.timeout(timeout) do
+        job.perform(*args)
+      end
 
       # Exit is not a good idea within a Rails process but Rubocop doesn't know
       # that we are in a forked process.
@@ -13,5 +20,9 @@ class JobProcessor
     end
 
     Process.waitall
+  ensure
+    # If this Puma thread is interrupted then we need to detach the child
+    # process to avoid it becoming a zombie.
+    Process.detach(child)
   end
 end