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Avoid deadlock when creating ready execution #229

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Avoid deadlock when creating ready execution #229

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2 changes: 1 addition & 1 deletion app/models/solid_queue/ready_execution.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ def lock_candidates(job_ids, process_id)
return [] if job_ids.none?

SolidQueue::ClaimedExecution.claiming(job_ids, process_id) do |claimed|
where(job_id: claimed.pluck(:job_id)).delete_all
where(id: where(job_id: claimed.pluck(:job_id)).pluck(:id)).delete_all
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The only problem with this one is that it introduces another query in the hot path... it's probably ok, but I think we could save it because we've already done a query to ready_executions before, where we select only the job_id. We could select id, job_id, and then filter in memory for the ones that were actually claimed. Let me see how it'd look.

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This is what I had in mind:

diff --git a/app/models/solid_queue/claimed_execution.rb b/app/models/solid_queue/claimed_execution.rb
index f2ed58d..c67c62a 100644
--- a/app/models/solid_queue/claimed_execution.rb
+++ b/app/models/solid_queue/claimed_execution.rb
@@ -15,7 +15,7 @@ class SolidQueue::ClaimedExecution < SolidQueue::Execution

       insert_all!(job_data)
       where(job_id: job_ids, process_id: process_id).load.tap do |claimed|
-        block.call(claimed)
+        block.call(claimed.map(&:job_id))
       end
     end

diff --git a/app/models/solid_queue/ready_execution.rb b/app/models/solid_queue/ready_execution.rb
index 8eeaddc..2c68cf9 100644
--- a/app/models/solid_queue/ready_execution.rb
+++ b/app/models/solid_queue/ready_execution.rb
@@ -24,20 +24,21 @@ module SolidQueue
           return [] if limit <= 0

           transaction do
-            job_ids = select_candidates(queue_relation, limit)
-            lock_candidates(job_ids, process_id)
+            candidates = select_candidates(queue_relation, limit)
+            lock_candidates(candidates, process_id)
           end
         end

         def select_candidates(queue_relation, limit)
-          queue_relation.ordered.limit(limit).non_blocking_lock.pluck(:job_id)
+          queue_relation.ordered.limit(limit).non_blocking_lock.select(:id, :job_id)
         end

-        def lock_candidates(job_ids, process_id)
-          return [] if job_ids.none?
+        def lock_candidates(executions, process_id)
+          return [] if executions.none?

-          SolidQueue::ClaimedExecution.claiming(job_ids, process_id) do |claimed|
-            where(job_id: claimed.pluck(:job_id)).delete_all
+          SolidQueue::ClaimedExecution.claiming(executions.map(&:job_id), process_id) do |claimed_job_ids|
+            ids_to_delete = executions.index_by(&:job_id).values_at(*claimed_job_ids).map(&:id)
+            where(id: ids_to_delete).delete_all
           end
         end

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Hi, @rosa . Thank you for your response.

The solution is good for me. It's more efficient.

Will the fix be included in the next release version?

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Yes! Let me add that one and get a new version out.

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Thanks!

end
end

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