Looks like you've hit a bug (not the first time I've seen this in relation to C* configs). compaction_large_partition_warning_threshold_mb resolves to an int, and in the codebase is represented in bytes. 4096 * 1024 * 1024 and you've got some serious overflow. Granted, you should have this warning set considerably lower than 4096MB anyway. Try set it to 1024MB. Looks like this affects multiple versions so I'll create a JIRA/patch soon.
Relevant code: public static int getCompactionLargePartitionWarningThreshold() { return conf.compaction_large_partition_warning_threshold_mb * 1024 * 1024; }