What version is your AWS Java SDK Dependency (e.g. DynamoDB), JDK version, and Datomic Version? The problem is in the stacktrace: > {:type java.lang.ClassNotFoundException > :message "com.amazonaws.retry.RetryMode" > :at [java.net.URLClassLoader findClass "URLClassLoader.java" 382]}]

Thanks! I'll grab that information, its harder then it should be to sure. I assume the problem is described in the stacktrace, but i don't understand how. How i read the part you highlighted is "i wasn't able to find a function, maybe the url class loader" Then an unrelated message that isn't at all a message but just the words retry, implying that something was... retried. What do you read?

jdk: openjdk8 datomic version:

[com.datomic/datomic-pro "0.9.5966" :exclusions [com.google.guava/guava commons-codec org.apache.httpcomponents/httpcore org.apache.httpcomponents/httpclient]]

[com.amazonaws/aws-java-sdk-core "1.11.664" :exclusions [com.fasterxml.jackson.core/jackson-annotations com.fasterxml.jackson.core/jackson-databind]]
                 [org.sharetribe/aws-sig4 "0.1.3"]

i'll be asleep soon. thanks for even looking at this 🙂 . Err if you don't have much time just get me your gut call on what the issue is, im thinking networking right now.

also, your first thoughts on how to troubleshoot this kind of thing might be just, if not more helpful for me.

My read is: • Your apps call to d/create-database is the first time the AWS client is initialized (because it has to connect to DynamoDB) • When that happens, Datomic requires / imports the AWS and DynamoDB specific classes it needs. You can see that after [datomic.require$require_and_run invokeStatic "require.clj" 21] in the stacktrace. • Inside the datomic.aws namespace (per the stacktrace section w/ [datomic.aws__init <clinit> nil -1] ) , we attempt to load the class com.amazonaws.retry.RetryMode (not use it, just load the class) • Per the below message, we can't find the class.

{:type java.lang.ClassNotFoundException
  :message "com.amazonaws.retry.RetryMode"
  :at [java.net.URLClassLoader findClass "URLClassLoader.java" 382]}

thanks for the perspective, i guess i had blocked the idea that it actually couldnt find the class because i'm not sure how we could have ended up there. But ill retrace my steps.

Before you create the database, try listing databases and see if you get the same result

How many results does that query return? Is that a Cardinality many attribute? Is that attribute indexed? Unique? What version of datomic are you running? You keep saying “required” but I’m not clear what that means to you. I understand cost saving, but why is getting the peer running with 2g an objective?

I assume this is a merely representative query and not the full query. But if it is the full query, consider using d/datoms and processing lazily if you need bounded memory use

Using only 2gb for a peer with ad hoc query loads is really aggressive

Peers are more like “read replicas” in a traditional sql db and should be sized accordingly, unless you have written queries very carefully with memory use and small intermediate result sets in mind

Well, I want it down to 2GB in staging. Not immediately crashing with 2GB is a goal.

We've already paid for reserve instances in AWS, and seeing slowness with 16GB of RAM. If we ever needed go beyond 16GB, we'd be in a lot of trouble. 2GB without crashing sounds like a reasonable goal to optimize for prod

"seeing slowness", there are more approaches than just adding RAM to improve Datomic Performance.

You can check the logs and metrics