Yifan Cai created CASSANDRA-16760:
-------------------------------------
Summary: JMXTimer exposes attributes in inconsistent time units
Key: CASSANDRA-16760
URL: https://issues.apache.org/jira/browse/CASSANDRA-16760
Project: Cassandra
Issue Type: Improvement
Components: Legacy/Observability
Reporter: Yifan Cai
Assignee: Yifan Cai
JMXTimer objects are constructed with a duration time unit, which is fixed to
MICROSECONDS in the codebase. According to that, we should expect the time
values returned from the JXMTimer are in micros.
However, the time unit is inconsistent among the JMXTimer attributes.
Most of the attributes such as percentiles and mean values returned are in
micros, except Values and RecentValues.
Those 2 attributes expose the raw histogram values of the underlying Timer
(CodaHale) and the values are fixed to be based on nanos.
The inconsistency leads to confusion and mis-interpretation of the values, if
the end user is not familiar with the implementation details. One may consider
the Values and RecentValues are also in micros.
Besides the confusion, given the intention is to record the time values in the
micros resolution, we do not need to allocate 165 buckets in the
DecayingEstimatedHistogramReservoir. 165 buckets is necessary for nanos, but
not for micros. We can only allocate 90 buckets and it should reduce ~50%
memory footprint used by the Timers.
I'd like to propose an approach to scale the values being recorded in the
reservoirs used by Timers and reduce the allocation.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
