Also, what does this message mean?  I saw it earlier on in the logs:

[DEBUG] [08/05/2016 05:04:50.450] 
[ClusterSystem-akka.actor.default-dispatcher-17] 
[akka://ClusterSystem/system/endpointManager/reliableEndpointWriter-akka.tcp%3A%2F%2FClusterSystem%4010.0.3.176%3A2552-6]
 
unhandled message from 
Actor[akka://ClusterSystem/system/endpointManager/reliableEndpointWriter-akka.tcp%3A%2F%2FClusterSystem%4010.0.3.176%3A2552-6#1200432312]:
 
Ungate

On Friday, August 5, 2016 at 12:58:55 PM UTC-7, Eric Swenson wrote:
>
> Our akka-cluster-sharding service went down last night. In the middle of 
> processing akka-http requests (and sending these requests to a sharding 
> region for processing) on a 10-node cluster, one of the requests got an 
> "ask timeout" exception:
>
> [ERROR] [08/05/2016 05:04:51.077] 
> [ClusterSystem-akka.actor.default-dispatcher-16] 
> [akka.actor.ActorSystemImpl(ClusterSystem)] Error during processing of 
> request HttpRequest(HttpMetho\
>
> d(GET),
> http://eim.staging.example.com/eim/check/a0afbad4-69a8-4487-a6fb-f3e884a8d0aa?cache=false&timeout=15,List(Host:
>  
> eim.staging.example.com, X-Real-Ip: 10.0.3.9, X-Forwarded-Fo\
>
> r: 10.0.3.9, Connection: upgrade, Accept: */*, Accept-Encoding: gzip, 
> deflate, compress, Authorization: Bearer 
> aaa-1ZdrFpgR5AyOGa69Q2s3fwv_y5zz9UCL5F85Hc, User-Agent: python-requests\
>
> /2.2.1 CPython/2.7.6 Linux/3.13.0-74-generic, Timeout-Access: 
> <function1>),HttpEntity.Strict(application/json,),HttpProtocol(HTTP/1.1))  
>                                                
>
> akka.pattern.AskTimeoutException: 
> Recipient[Actor[akka://ClusterSystem/system/sharding/ExperimentInstance#-1675878517]]
>  
> had already been terminated. Sender[null] sent the message of t\
>
> ype "com.genecloud.eim.ExperimentInstance$Commands$CheckExperiment".       
>                                                                             
>                                  
>
> As the error message says, the reason for the ask timeout was because the 
> actor (sharding region?) had been terminated.  
>
> Looking back in the logs, I see that everything was going well for quite 
> some time, until the following:
>
>
> [DEBUG] [08/05/2016 05:04:50.480] 
> [ClusterSystem-akka.actor.default-dispatcher-2] [akka.tcp://
> ClusterSystem@10.0.3.103:2552/system/IO-TCP/selectors/$a/955] Resolving 
> login.dev.example.com before connecting
>
> [DEBUG] [08/05/2016 05:04:50.480] 
> [ClusterSystem-akka.actor.default-dispatcher-2] [akka.tcp://
> ClusterSystem@10.0.3.103:2552/system/IO-TCP/selectors/$a/955] Attempting 
> connection to [login.dev.example.com/52.14.30.100:443]
>
> [DEBUG] [08/05/2016 05:04:50.481] 
> [ClusterSystem-akka.actor.default-dispatcher-6] [akka.tcp://
> ClusterSystem@10.0.3.103:2552/system/IO-TCP/selectors/$a/955] Connection 
> established to [login.dev.example.com:443]
>
> [DEBUG] [08/05/2016 05:04:50.481] 
> [ClusterSystem-akka.actor.default-dispatcher-5] 
> [akka://ClusterSystem/system/IO-TCP] no longer watched by 
> Actor[akka://ClusterSystem/user/StreamSupervisor-7/$$H#-1778344261]
>
> [DEBUG] [08/05/2016 05:04:50.481] 
> [ClusterSystem-akka.actor.default-dispatcher-5] 
> [akka://ClusterSystem/system/IO-TCP/selectors/$a/955] now watched by 
> Actor[akka://ClusterSystem/user/StreamSupervisor-7/$$H#-1778344261]
>
> [DEBUG] [08/05/2016 05:04:50.483] 
> [ClusterSystem-akka.actor.default-dispatcher-17] 
> [akka://ClusterSystem/user/StreamSupervisor-7] now supervising 
> Actor[akka://ClusterSystem/user/Strea
> mSupervisor-7/flow-993-1-unknown-operation#819117275]
>
> [DEBUG] [08/05/2016 05:04:50.484] 
> [ClusterSystem-akka.actor.default-dispatcher-2] 
> [akka://ClusterSystem/user/StreamSupervisor-7/flow-993-1-unknown-operation] 
> started (akka.stream.impl.io.TLSActor@66dd942c)
>
> [INFO] [08/05/2016 05:04:50.526] 
> [ClusterSystem-akka.actor.default-dispatcher-17] 
> [akka.cluster.Cluster(akka://ClusterSystem)] Cluster Node [akka.tcp://
> ClusterSystem@10.0.3.103:2552] - Shutting down myself
>
> [INFO] [08/05/2016 05:04:50.527] 
> [ClusterSystem-akka.actor.default-dispatcher-17] 
> [akka.cluster.Cluster(akka://ClusterSystem)] Cluster Node [akka.tcp://
> ClusterSystem@10.0.3.103:2552] - Shutting down...
>
> [DEBUG] [08/05/2016 05:04:50.528] 
> [ClusterSystem-akka.actor.default-dispatcher-3] 
> [akka://ClusterSystem/system/cluster/core] stopping
>
> [DEBUG] [08/05/2016 05:04:50.528] 
> [ClusterSystem-akka.actor.default-dispatcher-16] 
> [akka://ClusterSystem/system/cluster/heartbeatReceiver] stopped
>
> [DEBUG] [08/05/2016 05:04:50.539] 
> [ClusterSystem-akka.actor.default-dispatcher-16] 
> [akka://ClusterSystem/system/cluster/metrics] stopped
>
> [DEBUG] [08/05/2016 05:04:50.540] 
> [ClusterSystem-akka.actor.default-dispatcher-18] 
> [akka://ClusterSystem/system/cluster] stopping
>
> [INFO] [08/05/2016 05:04:50.573] 
> [ClusterSystem-akka.actor.default-dispatcher-18] [akka.tcp://
> ClusterSystem@10.0.3.103:2552/system/sharding/ExperimentInstanceCoordinator] 
> Self removed\
>
> , stopping ClusterSingletonManager
>
> [DEBUG] [08/05/2016 05:04:50.573] 
> [ClusterSystem-akka.actor.default-dispatcher-18] 
> [akka://ClusterSystem/system/sharding/ExperimentInstanceCoordinator] 
> stopping
>
>
> As you can see, from the "Resolving..." and "Attempting connection" log 
> messages, an actor was happily sending off an HTTP request to another 
> microservice using TLS, but just after this point, the cluster node said it 
> was "Shutting down myself".  This killed the ClusterSingletonManager.  From 
> that point on, all incoming requests to the shard region were rejected 
> (because it was down).
>
>
> Now the node was NOT down, and there are tons of messages after this point 
> in the log -- and any request that came in from akka-http and was forwarded 
> to the sharding region timed out (for the same reason).  This basically 
> meant that the service rejected all subsequent requests to this node with 
> http status code 500.  
>
>
> There is no code in our software that shuts down any cluster member.  
>
>
> We were firing a lot of requests to the service at the time this happened, 
> but the average cpu utilization on the 10-node cluster that ran this 
> microservice was never over 30%.
>
>
> Why would the node decide to shut itself down? 
>
>
> Any help would be appreciated. I'm concerned about the robustness of Akka 
> in production since we hope to scale to a much greater degree than 10 
> nodes....
>
>
> -- Eric
>
>
>
>

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