Catching a few MangoGT units hanging, to find Out Of Memory errors in the logs:

Dec 06 01:00:43 mangoGT5176 start-mango.sh[529]: Exception in thread "high-pool-2-thread-5894" com.infiniteautomation.tsdb.IasTsdbException: java.io.IOException: Map failed
Dec 06 01:00:43 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.tsdb.impl.IasTsdbImpl.count(IasTsdbImpl.java:1124)
Dec 06 01:00:43 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.nosql.InternalGenericDao.rangeCount(InternalGenericDao.java:393)
Dec 06 01:00:43 mangoGT5176 start-mango.sh[529]:         at 
[snipped]
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.serotonin.m2m2.persistent.pub.SyncHandler$PointSync.checkRangeImpl(SyncHandler.java:514)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.serotonin.m2m2.persistent.pub.SyncHandler$PointSync.checkRange(SyncHandler.java:345)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.serotonin.m2m2.persistent.pub.SyncHandler$PointSync.checkPoint(SyncHandler.java:326)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.serotonin.m2m2.persistent.pub.SyncHandler$PointSync.run(SyncHandler.java:276)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.serotonin.timer.sync.Synchronizer$TaskWrapper.run(Synchronizer.java:150)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.serotonin.timer.Task.runTask(Task.java:179)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.serotonin.timer.TaskWrapper.run(TaskWrapper.java:23)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at java.base/java.lang.Thread.run(Thread.java:830)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]: Caused by: java.io.IOException: Map failed
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at java.base/sun.nio.ch.FileChannelImpl.map(FileChannelImpl.java:1017)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.tsdb.impl.ChecksumMappedByteBufferInputStream.<init>(ChecksumMappedByteBufferInputStream.java:41)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.tsdb.impl.ReversibleShard.openDataIn(ReversibleShard.java:250)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.tsdb.impl.Shard.query(Shard.java:473)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.tsdb.impl.CompressibleShard.query(CompressibleShard.java:391)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.tsdb.impl.Series.query(Series.java:532)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at com.infiniteautomation.tsdb.impl.IasTsdbImpl.count(IasTsdbImpl.java:1095)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         ... 48 more
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]: Caused by: java.lang.OutOfMemoryError: Map failed
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at java.base/sun.nio.ch.FileChannelImpl.map0(Native Method)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         at java.base/sun.nio.ch.FileChannelImpl.map(FileChannelImpl.java:1014)
Dec 06 01:02:22 mangoGT5176 start-mango.sh[529]:         ... 54 more

Suggestions? Adjust thread pools? Swap?