Cassandra CommitLog Directory Forgetting To Remove Files

Version: DSE 6.7.5, CQL spec 3.4.5.
I have 8GB commitlog_total_space_in_mb.
Folder is currently at 13GB.
Looking at the date stamps in the folder it appears that it forgets about commitlogs or it may be failing to delete the commitlogs when it flushes memtables.
Happens on multiple nodes.

-rw-r--r--. 1 cassandra cassandra 33554338 Sep 20 02:00 CommitLog-600-1568892978830.log
-rw-r--r--. 1 cassandra cassandra 33554227 Sep 20 02:02 CommitLog-600-1568892978853.log
-rw-r--r--. 1 cassandra cassandra 33554217 Sep 20 02:02 CommitLog-600-1568892978862.log
-rw-r--r--. 1 cassandra cassandra 33554337 Sep 20 02:03 CommitLog-600-1568892978863.log
-rw-r--r--. 1 cassandra cassandra 33554169 Sep 20 02:04 CommitLog-600-1568892978864.log
-rw-r--r--. 1 cassandra cassandra 33554412 Sep 20 08:19 CommitLog-600-1568892954896.log
-rw-r--r--. 1 cassandra cassandra 33554326 Sep 20 08:19 CommitLog-600-1568892954901.log
-rw-r--r--. 1 cassandra cassandra 33554133 Sep 20 08:20 CommitLog-600-1568892954904.log
-rw-r--r--. 1 cassandra cassandra 33554281 Sep 20 08:20 CommitLog-600-1568892954905.log
-rw-r--r--. 1 cassandra cassandra 33553885 Sep 20 08:20 CommitLog-600-1568892954906.log

When i perform a nodetool flush/drain it will not remove any of the old files.

When I start the node back up it goes through them and crashes around the final commitlog. https://pastebin.com/Kw9Kee5C

CassandraDaemon.java:129 - Exception in thread Thread[PerDiskMemtableFlushWriter_0:11,5,main] java.lang.AssertionError: null

It wont start back up unless I move some of the last commitlogs out or all of them out.

What can I do to fix this problem

Solution

I have resolved this for my issue for the time being by changing compaction to

compaction = {'class': 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy'}

For some reason having cell type of map with the following compaction was causing me the errors.

{'class': 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy', 'compaction_window_size': '30', 'compaction_window_unit': 'DAYS', 'max_threshold': '32', 'min_threshold': '4', 'split_during_flush': 'true'}