3570: Use exit code 75 to mean "temporary locking failure". Add comments.

[arvados.git] / services / api / script / crunch-dispatch.rb

diff --git a/services/api/script/crunch-dispatch.rb b/services/api/script/crunch-dispatch.rb
index 5a990f0cb41ad30bd8832399a0d40c1839f2460e..154fcf31455ac821b76287029114441e2c3849aa 100755 (executable)
--- a/services/api/script/crunch-dispatch.rb
+++ b/services/api/script/crunch-dispatch.rb
@@ -375,11 +375,11 @@ class Dispatcher
       $stderr.puts j_done[:stderr_buf] + "\n"
     end
 
-    # Wait the thread
-    j_done[:wait_thr].value
+    # Wait the thread (returns a Process::Status)
+    exit_status = j_done[:wait_thr].value
 
     jobrecord = Job.find_by_uuid(job_done.uuid)
-    if jobrecord.started_at
+    if exit_status.to_i != 75 and jobrecord.started_at
       # Clean up state fields in case crunch-job exited without
       # putting the job in a suitable "finished" state.
       jobrecord.running = false
@@ -392,7 +392,18 @@ class Dispatcher
       # Don't fail the job if crunch-job didn't even get as far as
       # starting it. If the job failed to run due to an infrastructure
       # issue with crunch-job or slurm, we want the job to stay in the
-      # queue.
+      # queue. If crunch-job exited after losing a race to another
+      # crunch-job process, it exits 75 and we should leave the job
+      # record alone so the winner of the race do its thing.
+      #
+      # There is still an unhandled race condition: If our crunch-job
+      # process is about to lose a race with another crunch-job
+      # process, but crashes before getting to its "exit 75" (for
+      # example, "cannot fork" or "cannot reach API server") then we
+      # will assume incorrectly that it's our process's fault
+      # jobrecord.started_at is non-nil, and mark the job as failed
+      # even though the winner of the race is probably still doing
+      # fine.
     end
 
     # Invalidate the per-job auth token