SIGSTP should be SIGTSTP

lib/gitlab/sidekiq_middleware/memory_killer.rb

@@ -31,7 +31,7 @@ module Gitlab
 
           # Wait `GRACE_TIME` to give the memory intensive job time to finish.
           # Then, tell Sidekiq to stop fetching new jobs.
-          wait_and_signal(GRACE_TIME, 'SIGSTP', 'stop fetching new jobs')
+          wait_and_signal(GRACE_TIME, 'SIGTSTP', 'stop fetching new jobs')
 
           # Wait `SHUTDOWN_WAIT` to give already fetched jobs time to finish.
           # Then, tell Sidekiq to gracefully shut down by giving jobs a few more

spec/lib/gitlab/sidekiq_middleware/memory_killer_spec.rb

@@ -37,7 +37,7 @@ describe Gitlab::SidekiqMiddleware::MemoryKiller do
 
     it 'sends the STP, TERM and KILL signals at expected times' do
       expect(subject).to receive(:sleep).with(15 * 60).ordered
-      expect(Process).to receive(:kill).with('SIGSTP', pid).ordered
+      expect(Process).to receive(:kill).with('SIGTSTP', pid).ordered
 
       expect(subject).to receive(:sleep).with(30).ordered
       expect(Process).to receive(:kill).with('SIGTERM', pid).ordered