cpoerschke commented on code in PR #96:
URL: https://github.com/apache/solr/pull/96#discussion_r1311918794
##########
solr/core/src/java/org/apache/solr/util/circuitbreaker/CPUCircuitBreaker.java:
##########
@@ -17,54 +17,49 @@
package org.apache.solr.util.circuitbreaker;
+import com.codahale.metrics.Gauge;
+import com.codahale.metrics.Metric;
import java.lang.invoke.MethodHandles;
-import java.lang.management.ManagementFactory;
-import java.lang.management.OperatingSystemMXBean;
+import org.apache.solr.core.SolrCore;
+import org.apache.solr.metrics.SolrMetricManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Tracks current CPU usage and triggers if the specified threshold is
breached.
*
- * <p>This circuit breaker gets the average CPU load over the last minute and
uses that data to take
- * a decision. We depend on OperatingSystemMXBean which does not allow a
configurable interval of
- * collection of data. //TODO: Use Codahale Meter to calculate the value
locally.
- *
- * <p>The configuration to define which mode to use and the trigger threshold
are defined in
- * solrconfig.xml
+ * <p>This circuit breaker gets the recent average CPU usage and uses that
data to take a decision.
+ * We depend on OperatingSystemMXBean which does not allow a configurable
interval of collection of
+ * data.
*/
public class CPUCircuitBreaker extends CircuitBreaker {
private static final Logger log =
LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
- private static final OperatingSystemMXBean operatingSystemMXBean =
- ManagementFactory.getOperatingSystemMXBean();
+ private static boolean warningLogged = false;
Review Comment:
So an alternative to `boolean` would be `AtomicBoolean` then, say. Since the
variable is only read (and set) in an error scenario there then maybe wouldn't
be any concern re: atomic being more expensive.
But actually, I wonder, if failure to acquire the inputs is systemic,
wouldn't one want to know as early as possible e.g. in the constructor and to
at least log a warning there, maybe an error or to throw an exception even?
* That's not specific to this class I guess.
* In the case of a search circuit breaker one could imagine ping-like
behaviour resulting in the warning being logged ahead of 'real' traffic
reaching the core.
* In the case of an update circuit breaker would it conceptually only be the
first real update request that results in a warning and that could be confusing
or undesirable, whereas a warning on startup is more harmless?
If the constructor made a `isTripped(true)` call then no `warningLogged`
member variable would be needed and that would also help with the _the value of
these parameters will be set correctly before invoking getDebugInfo()_
assumption at line 42/43.
```
public boolean isTripped() {
return isTripped(false);
}
private boolean isTripped(boolean logWarning) {
...
}
```
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