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Walter Underwood commented on SOLR-15056: ----------------------------------------- Using load average needs a different threshold, so I'd make it a different circuit breaker instead of switching it out. Copy the existing load average circuit breaker, use a more clear name, and figure out how to document that a limit of 1000 is really a limit of 10.0. Maybe even explain that load average is quite different on different OSes. Linux includes processes in iowait, other Unixes don't. I'd rather use a threshold of 0.95 to mean 0.95 instead of using 95 to mean 0.95, but that is a breaking change. > CPU circuit breaker needs to use CPU utilization, not Unix load average > ----------------------------------------------------------------------- > > Key: SOLR-15056 > URL: https://issues.apache.org/jira/browse/SOLR-15056 > Project: Solr > Issue Type: Bug > Security Level: Public(Default Security Level. Issues are Public) > Components: metrics > Affects Versions: 8.7 > Reporter: Walter Underwood > Priority: Major > Labels: Metrics > Attachments: SOLR-15056.patch > > > The config range, 50% to 95%, assumes that the circuit breaker is triggered > by a CPU utilization metric that goes from 0% to 100%. But the code uses the > metric OperatingSystemMXBean.getSystemLoadAverage(). That is an average of > the count of processes waiting to run. It is effectively unbounded. I've seen > it as high as 50 to 100. It is not bound by 1.0 (100%). > A good limit for load average would need to be aware of the number of CPUs > available to the JVM. A load average of 8 is no problem for a 32 CPU host. It > is a critical situation for a 2 CPU host. > Also, load average is a Unix OS metric. I don't know if it is even available > on Windows. > Instead, use a CPU utilization metric that goes from 0.0 to 1.0. A good > choice is OperatingSystemMXBean.getSystemCPULoad(). This name also uses > "load", but it is a usage metric. > From the Javadoc: > > Returns the "recent cpu usage" for the whole system. This value is a double > >in the [0.0,1.0] interval. A value of 0.0 means that all CPUs were idle > >during the recent period of time observed, while a value of 1.0 means that > >all CPUs were actively running 100% of the time during the recent period > >being observed. All values betweens 0.0 and 1.0 are possible depending of > >the activities going on in the system. If the system recent cpu usage is not > >available, the method returns a negative value. > https://docs.oracle.com/javase/7/docs/jre/api/management/extension/com/sun/management/OperatingSystemMXBean.html#getSystemCpuLoad() > Also update the documentation to explain which JMX metrics are used for the > memory and CPU circuit breakers. > -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org