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Posted to commits@cassandra.apache.org by "Brad Schoening (Jira)" <ji...@apache.org> on 2024/09/09 17:43:00 UTC
[jira] [Assigned] (CASSANDRA-18454) Enhance nodetool gcstats
[ https://issues.apache.org/jira/browse/CASSANDRA-18454?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Brad Schoening reassigned CASSANDRA-18454:
------------------------------------------
Assignee: (was: Dhanush Ananthkar)
> Enhance nodetool gcstats
> -------------------------
>
> Key: CASSANDRA-18454
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18454
> Project: Cassandra
> Issue Type: Improvement
> Components: Tool/nodetool
> Reporter: Brad Schoening
> Priority: Normal
>
> Nodetool gcstats provides only a brief one line output of historical GC activity with Max, Total, Stdev, etc
> {noformat}
> % nodetool gcstats
> Interval (ms) Max GC Elapsed (ms)Total GC Elapsed (ms)Stdev GC Elapsed (ms) GC Reclaimed (MB) Collections Direct Memory Bytes
> 11979 0 0 NaN 0 0 -1
> {noformat}
> 1. Performance of garbage collection is such an key part of Cassandra performance that it would be helpful to have more complete metrics with *gcstats* here. The MBean java.lang.GarbageCollector has recent statistic which could be added in events/second for:
> * GcThreadCount
> * Duration
> The current size of eden / survivor / old space and humongous allocations should be shown as well.
> The metrics show with jhsdb jmap would be very helpful as well, if they're available.
> [https://docs.oracle.com/en/java/javase/11/troubleshoot/diagnostic-tools.html#GUID-A69901EC-F87D-4B63-A8B7-DE8684AD4FF9]
> 2. Since physical memory is also a critical part of GC performance, it would be useful to report the following MBeans
> |[cassandra_os_free_memory_bytes|https://github.com/instaclustr/cassandra-exporter/wiki/Exported-Metrics#_cassandra_os_free_memory_bytes]|Amount of free physical memory available (as seen by the Cassandra JVM process).|
> |[cassandra_os_free_swap_bytes|https://github.com/instaclustr/cassandra-exporter/wiki/Exported-Metrics#_cassandra_os_free_swap_bytes]|Amount of free swap space available (as seen by the Cassandra JVM process).|
> |[cassandra_os_memory_bytes_total|https://github.com/instaclustr/cassandra-exporter/wiki/Exported-Metrics#_cassandra_os_memory_bytes_total]|Total physical memory available (as seen by the Cassandra JVM process).|
> |[cassandra_os_swap_bytes_total|https://github.com/instaclustr/cassandra-exporter/wiki/Exported-Metrics#_cassandra_os_swap_bytes_total]|Total swap space available (as seen by the Cassandra JVM process).|
> or use [/proc/meminfo|https://stackoverflow.com/questions/59581597/get-available-ram-in-java] SystemInfo.java already reads /proc/<pid>/limits on Linux systems.
> 3. Status of memlock
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