[ https://issues.apache.org/jira/browse/CASSANDRA-14281?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jeff Jirsa updated CASSANDRA-14281: ----------------------------------- Labels: perfomance (was: ) > Improve LatencyMetrics performance by reducing write path processing > -------------------------------------------------------------------- > > Key: CASSANDRA-14281 > URL: https://issues.apache.org/jira/browse/CASSANDRA-14281 > Project: Cassandra > Issue Type: Improvement > Components: Core > Reporter: Michael Burman > Assignee: Michael Burman > Priority: Major > Labels: perfomance > Fix For: 4.0 > > Attachments: bench.png, bench2.png, benchmark.html, benchmark2.png > > > Currently for each write/read/rangequery/CAS touching the CFS we write a > latency metric which takes a lot of processing time (up to 66% of the total > processing time if the update was empty). > The way latencies are recorded is to use both a dropwizard "Timer" as well as > "Counter". Latter is used for totalLatency and the previous is decaying > metric for rates and certain percentile metrics. We then replicate all of > these CFS writes to the KeyspaceMetrics and globalWriteLatencies. > Instead of doing this on the write phase we should merge the metrics when > they're read. This is much less common occurrence and thus we save a lot of > CPU time in total. This also speeds up the write path. > Currently, the DecayingEstimatedHistogramReservoir acquires a lock for each > update operation, which causes a contention if there are more than one thread > updating the histogram. This impacts scalability when using larger machines. > We should make it lock-free as much as possible and also avoid a single > CAS-update from blocking all the concurrent threads from making an update. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org