Hi, I have been working on some experiments for Cassandra and found some log messages as follows in debug.log. I am not sure what it exactly is, so I would appreciate if someone gives me some explanations about it.
In my verification, a Cassandra node runs as a stand-alone server on Amazon EC2 instance(t2.medium). And I insert 1 Billion records (about 100GB data size) to a table from a client application (which runs on another instance separated from Cassandra node). After insertion, Cassandra continues it's I/O activities for (probably) compaction and keep logging the messages as follows: --- ... DEBUG [NonPeriodicTasks:1] 2016-03-16 09:59:25,170 FileCacheService.java:102 - Evicting cold readers for /var/lib/cassandra/data/system/local-7ad54392bcdd35a684174e047860b377/la-6-big-Data.db DEBUG [NonPeriodicTasks:1] 2016-03-16 09:59:31,780 FileCacheService.java:177 - Invalidating cache for /var/lib/cassandra/data/test/user-3d988520e9e011e59d830f00df8833fa/tmplink-la-8348-big-Data.db DEBUG [NonPeriodicTasks:1] 2016-03-16 09:59:36,899 FileCacheService.java:177 - Invalidating cache for /var/lib/cassandra/data/test/user-3d988520e9e011e59d830f00df8833fa/tmplink-la-8348-big-Data.db DEBUG [NonPeriodicTasks:1] 2016-03-16 09:59:42,187 FileCacheService.java:177 - Invalidating cache for /var/lib/cassandra/data/test/user-3d988520e9e011e59d830f00df8833fa/tmplink-la-8348-big-Data.db DEBUG [NonPeriodicTasks:1] 2016-03-16 09:59:47,308 FileCacheService.java:177 - Invalidating cache for /var/lib/cassandra/data/test/user-3d988520e9e011e59d830f00df8833fa/tmplink-la-8348-big-Data.db ... --- I guess these messages are related to the compaction process and FileCacheService was invalidating cache which associated with a SSTable file. But I'm not sure what it does actually mean. When the cache is invalidated? And What happens is after cache invalidation? Regards, Satoshi
