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https://issues.apache.org/jira/browse/CASSANDRA-18454?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17865197#comment-17865197
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Dhanush Ananthkar commented on CASSANDRA-18454:
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{color:#000000}GC Threads: 1{color}
{color:#000000}Duration: 15 ms{color}
{color:#000000}MemLock: false{color}
{color:#000000} {color}
{color:#000000}OS Free Memory Bytes: 1000.2 MB{color}
{color:#000000}OS Total Memory Bytes: 16384.0 MB{color}
{color:#000000}OS In Use: 15383.8 MB / 16384.0 MB (93.9%){color}
{color:#000000} {color}
{color:#000000}Swap in Use: 4085.5 MB / 5120.0 MB (79.8%){color}
{color:#000000} {color}
{color:#000000} {color}{color:#000000}Interval (ms) Max GC Elapsed (ms)
Total GC Elapsed (ms) Stdev GC Elapsed (ms) {color}{color:#000000}
{color}{color:#000000}GC Reclaimed (MB) {color}{color:#000000}
{color}{color:#000000}Collections{color}{color:#000000}
{color}{color:#000000}Direct Memory Bytes{color}
{color:#000000}
{color}{color:#000000}18129{color}{color:#000000}
{color}{color:#000000}16{color}{color:#000000}
{color}{color:#000000}16 {color}{color:#000000}
{color}{color:#000000}0 {color}{color:#000000}
{color}{color:#000000}361 {color}{color:#000000}
{color}{color:#000000}1 {color}{color:#000000}
{color}{color:#000000}-1{color}
{color:#000000} {color}
{color:#000000}Heap memory used: 24 MB (18.8%){color}
{color:#000000} {color}{color:#000000}G1 Eden Space memory used: 15 MB
(34.9%){color}
{color:#000000} {color}{color:#000000}G1 Old Gen memory used: 8 MB
(10.1%){color}
{color:#000000} {color}{color:#000000}G1 Survivor Space memory used: 0 MB
(54.8%){color}
> 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
> Assignee: Dhanush Ananthkar
> 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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