8.x memory issue

I’m running Solr on 32-bit Ubuntu 18.04 LTS using OpenJDK 10.0.2. Up until now I have had no problem with Solr (started running it since 4.x), however after upgrading from 7.x to 8.x I am getting serious memory issues.

I have a small repository of 30,000 documents currently using Solr 7.1 for the search function. I attempted an upgrade to 8.1.1 and tried to perform a full reindex however, it manages about 300 documents and then dies from lack of memory (or so it says). I tried 8.1.0 with the same result. I then tried 8.0.0 which did successfully manage a full reindex but then after performing a couple of search queries died from lack of memory. I then tried 7.7.2 which worked fine. I have now gone back to my original 7.1 as I can’t risk 8.x in my production system.

I increased Xmx to 1024m (previously 512m) but that made no difference, it may be some other resource than memory, but if it is, it isn’t saying so, and it’s such a small repository it doesn’t seem to make sense to be running out of memory, and 7.x runs fine