Memory leak

[LennartRoeder]

Hi,
I had some serious memory issues. I could increase Memory to a certain point, but with the 90M entries I try to write, my performance drops, once I reach the memory limit with intensive GC activity. I solved it by simply switching to https://github.com/fusesource/leveldbjni.
Here is an example with a container limited to 900MB RAM. The same happens with 4, 8 or 12 GB RAM.

[pcmind]

Could you provide an example of code where it is possible to replicate your scenario? What kind of object is using all your memory? Witch object is retaining them?

Be aware that memory used by CPP code won't appear as heap usage nor will it be constraint by JVM max heap size.

[LennartRoeder]

@pcmind I am aware that the cpp memory does not effect the JVM, but my kubernetes metrics show no leakage there and the app does not crash or slow down due to lack of memory.

My keys look like this: WS_SHP_ARTICLE_kubis-10000002-1
The payload is an org.json.JSONArray with org.json.JSONObjects inside.

My small example has 20 million keys and 30gb data (The test in the screenshots was done with 2M entries and 1GB RAM).
I use a HashMap and insert the object to each key and when I know my JSONArray is complete, I persist it once, so I don't have to deal with IO on lookups. I tested batch and no batch operations and also tried to modify the Options of the levelDB connection.
The only thing I did not try is to convert the JSONArray to binary before inserting.

As for example code: I am way behind on schedule and will be leaving my team soon, so I need to get things done and can't spend any time on supplying it. Plus, by switching the lib, I solved my issue.
I however wanted to leave you and anybody who faces the same issue my solution, so this can be addressed.

[dreams-money]

This issue seems to be present in the Ergo blockchain's use of leveldb. Can be reproduced if anyone's interested: ergoplatform/ergo#1390