High CPU usage
Great! Thanks for your patience through the investigation and glad to hear it!
what is the takeaway from this issue?
On unix OS with a read heavy query load and lots of bacnet data sources use db.shardStreamType=MAPPED_BYTE_BUFFER and increase the "Batch write behind spawn threshold" to 500 and "Max batch write behind tasks" to 50?
Hi Craig, I would consider the following the things to take away:
On *nix operating systems MAPPED_BYTE_BUFFER is the fastest stream, but does not currently work on Windows. INPUT_STREAM is likely still the fastest option for Windows.
Having write behind instances between 2 and 8 is most efficient for most users, with 2-3 (active, not maximum) probably being best, but 1 being totally sufficient in a system not under heavy load. But, you can experiment with this through the spawn threshold setting very easily.
Meta points will expand their caches to requests for fixed numbers of values but not for time ranges, so if you're being weighted down by Meta points you can convert something like
p.pointValuesSince( now - oneMinute );into
p.last(30); //knowing it's a 2 second polland see performance improvments.
Well this problem has come back, all the changes we did before are still in place so I'm guessing those changes just helped the root cause be less of an issue or another issue has come up maybe just all the restarts during the last debugging helped. All cores are pinned this time.
There is a new version of the database our that does some more efficient batch processing. I would consider updating to get that version. We have an instance running on this latest version and it's been intaking 300,000 values/s for months. This takes the shape of new Mango NoSQL system settings.
We could also try to troubleshoot it through the same steps again (getting thread dumps) but I would speculate it's a combination of meta points putting a heavy query load and something else.
A restart fixed the issue, it looks like the issue takes some time to come back or maybe some task we do causes the issue to come back but here is a CPU non kernal over 4 weeks. The drops are all manual restarts. We will try to upgrade again today, the last try failed so we rolled back.
Can you post a graph of your memory usage over the same time period?
Basically 0 swap over the timeframe.
Virtual Memory Used
You could experiment with using the concurrent garbage collector instead of the parallel garbage collector. There is the script Mango/bin/ext-available/concurrent-garbage-collector.sh to be placed in Mango/bin/ext-enabled/ if you're on Linux or Mac. GC tuning can take some effort, and it helps to log the output as well to know the effects changes have.
Another suggestion may be to encourage you to play with it and give us more information to work with.
We did get the upgrade to work today so we will let that sit as is for a while before I start changing things again. We do get a few of these now:
High priority task: com.infiniteautomation.nosql.MangoNoSqlBatchWriteBehindManager$PointDataCleaner was rejected because it is already running.