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Robert Stupp updated CASSANDRA-12731: ------------------------------------- Fix Version/s: 3.x > Remove IndexInfo cache from FileIndexInfoRetriever. > --------------------------------------------------- > > Key: CASSANDRA-12731 > URL: https://issues.apache.org/jira/browse/CASSANDRA-12731 > Project: Cassandra > Issue Type: Improvement > Components: Local Write-Read Paths > Reporter: Yasuharu Goto > Assignee: Yasuharu Goto > Fix For: 3.x > > Attachments: screenshot-1.png, screenshot-2.png > > > Hi guys. > In the patch of CASSANDRA-11206 , I found that FileIndexInfoRetriever > allocates a (potentially very large) IndexInfo array (up to the number of > IndexInfo in the RowIndexEntry has) as a cache in every single read path. > After some experiments using LargePartitionTest on my MacBook, I got results > that show that removing FileIndexInfoRetriever improves the performance for > large partitions like below (latencies reduced by 41% and by 45%). > {noformat} > // LargePartitionsTest.test_13_4G with cache by array > INFO [main] 2016-09-29 23:11:25,763 ?:? - SELECTs 1 for part=4194304k > total=16384M took 94197 ms > INFO [main] 2016-09-29 23:12:50,914 ?:? - SELECTs 2 for part=4194304k > total=16384M took 85151 ms > // LargePartitionsTest.test_13_4G without cache > INFO [main] 2016-09-30 00:13:26,050 ?:? - SELECTs 1 for part=4194304k > total=16384M took 55112 ms > INFO [main] 2016-09-30 00:14:12,132 ?:? - SELECTs 2 for part=4194304k > total=16384M took 46082 ms > {noformat} > Code is > [here|https://github.com/matope/cassandra/commit/86fb910a0e38f7520e1be40fb42f74a692f2ebce] > (based on trunk) > Heap memory usage during running LargePartitionsTest (except for 8G test) > with array cache(original) > !screenshot-1.png! > Heap memory usage during running LargePartitionsTest (except for 8G test) > without cache > !screenshot-2.png! > Of course, I have attempted to use some collection containers instead of a > plain array. But I could not recognize great improvement enough to justify > using these cache mechanism by them. (Unless I did some mistake or overlook > about this test) > || LargePartitionsTest.test_12_2G || SELECTs 1 (ms) || SELECTs 2 (ms) || Scan > (ms) || > |Original (array) | 62736 | 48562 | 41540 | > |ConcurrentHashMap | 47597 | 30854 | 18271 | > |ConcurrentHashMap 2nd trial |44036|26895|17443| > |LinkedHashCache (capacity=16, limit=10, fifo) 1st|42668|32165|17323| > |LinkedHashCache (capacity=16, limit=10, fifo) 2nd|48863|28066|18053| > |LinkedHashCache (capacity=16, limit=16, fifo) | 46979 | 29810 | 18620 | > |LinkedHashCache (capacity=16, limit=10, lru) | 46456 | 29749 | 20311 | > |No Cache | 47579 | 32480 | 18337 | > |No Cache 2nd trial | 46534 | 27670 | 18700 | > Code that I used for this comparison is > [here|https://github.com/matope/cassandra/commit/e12fcac77f0f46bdf4104ef21c6454bfb2bb92d0]. > LinkedHashCache is a simple fifo/lru cache that is extended by LinkedHashMap. > Scan is a execution time to iterate through the large partition. > So, in this issue, I'd like to propose to remove IndexInfo cache from > FileIndexInfoRetriever to improve the performance on large partitions. -- This message was sent by Atlassian JIRA (v6.3.4#6332)