Graphexp breaks connection to AWS Neptune

Hi!

I set up an AWS Neptune DB with a big graph inside. I also configured a ssh port forwarding using an EC2. At http://localhost:8182/status I receive this response, as expected:

{"status":"healthy","startTime":"Tue Apr 14 16:34:44 UTC 2020","dbEngineVersion":"1.0.2.2.R2","role":"writer","gremlin":{"version":"tinkerpop-3.4.3"},"sparql":{"version":"sparql-1.1"},"labMode":{"ObjectIndex":"disabled","ReadWriteConflictDetection":"enabled"}}

Then, I made a curl request:

curl 'http://localhost:8182/gremlin' -H 'Connection: keep-alive' -H 'Pragma: no-cache' -H 'Cache-Control: no-cache' -H 'Accept: */*' -H 'Sec-Fetch-Dest: empty' -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36' -H 'DNT: 1' -H 'Content-Type: application/x-www-form-urlencoded; charset=UTF-8' -H 'Origin: http://0.0.0.0:9000' -H 'Sec-Fetch-Site: cross-site' -H 'Sec-Fetch-Mode: cors' -H 'Referer: http://0.0.0.0:9000/graphexp.html' -H 'Accept-Language: en-US,en;q=0.9,it;q=0.8' --data '{"gremlin":"g.V().limit(1).valueMap()"}' --compressed

which answered me with the query results.

So, where is the problem? I opened graphexp.html and clicked on “Get graph info”. Now:

• graphexp tells me “(loading)”
• curl requests are pending
• gremlin queries from the EC2 are pending

The only way I could unlock this situation is stop-start the DB.

Is there a way to suppress graphexp requests after a timeout? It seems requests keep DB busy even if graphexp.html returns a timeout message; this way I have no options to interact with the machine.

Thanks.

[valeriazuccoli]

I realized that .limit(10000) does not return any MemoryError, while .sample(10000) does. I don’t know why, but I think this is a Neptune-related issue and not graphexp-related.

I believe limit solves the problem, but displaying a message seems necessary in this case. Maybe something like “You’re reading info about the top X nodes and vertices of your graph. Some others labels/properties may be available” may be useful.

Thank you very much!

Note: I don’t know if there is a cache system, but my “Get graph info” now takes only 10 seconds. Good point!

[bricaud]

Thanks @valeriazuccoli for your feedback!