> > Maybe the readRequests counter increments for each row read during a > scanNext call ?
Correct!! https://github.com/apache/hbase/blob/rel/1.2.12/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java#L2672 https://github.com/apache/hbase/blob/rel/1.2.12/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java#L1134 Maybe the readRequest counter increments with async replication jobs, > region replication, cross datacenter replication etc. readRequest should not be impacted due to replication. Regards, Ankit Singhal On Thu, Jul 4, 2019 at 6:59 PM Hakan Baba <[email protected]> wrote: > In hbase region and regionserver metrics I cannot understand the > relationships between metrics related to read requests, get and scanNext > operations. > > The hbase.regionserver.readRequestCount is documented here > <https://hbase.apache.org/book.html#rs_metrics> as: > > hbase.regionserver.readRequestCount > > The number of read requests received > > In addition to that, there are also get_num_ops and scanNext_num_ops > metrics. > I cannot find an official documentation for them. They are mentioned in > this ticket <https://issues.apache.org/jira/browse/HBASE-15376>. > > In the metrics I see, the readRequests are orders of magnitude larger than > the sum of all get and scanNext requests in one regionserver. For > example:[image: > ReadGetScanMetrics] <https://i.stack.imgur.com/3fyGk.png> > > Please note that the y-axis is in log scale. > > The plots are using these Wavefront queries > > ReadRequestRate > > sum(rate(ts(hbase.regionserver.server.readRequestCount, > source="*<sourceSelector>*" ))) > > GetNumRate > > sum(rate(ts(hbase.regionserver.regions.get_num_ops, > source="*<sourceSelector>*"))) > > ScanNumRate > > sum(rate(ts(hbase.regionserver.regions.scanNext_num_ops, > source="*<sourceSelector>*" ))) > > What may be the reason of that huge delta ? What does readRequest counter > include in addition to get and scanNext operations ? > > Some unproven theories of mine. > > 1. Maybe the readRequests counter increments for each row read during a > scanNext call ? > 2. Maybe the readRequest counter increments with async replication jobs, > region replication, cross datacenter replication etc. > > Note this is running HBase 1.2.0-cdh5.11.0 > > > You can see this question also in server fault, if you like to see a > different formatting. > > https://serverfault.com/q/973638/428655 > > Thanks > > Hakan >
