"Could not release " message happens sometimes in JavaMelody

Question

After we migrate to JavaMelody 1.88 from 1.68.1 we get this message. Usually after we start our app server? Can anybody help us?

java.io.IOException: Could not release [<any_path>/springe4b951a1e22fd7add5aed6f9f81d9023cca34a88.rrd], the file was never requested
    at net.bull.javamelody.internal.model.JRobin.createIOException(JRobin.java:569) ~[javamelody-core-1.88.0.jar:1.88.0]
    at net.bull.javamelody.internal.model.JRobin.createInstance(JRobin.java:166) ~[javamelody-core-1.88.0.jar:1.88.0]
    at net.bull.javamelody.internal.model.Collector.getRequestJRobin(Collector.java:907) ~[javamelody-core-1.88.0.jar:1.88.0]
    [...]
Caused by: org.jrobin.core.RrdException: Could not release [<any_path>/springe4b951a1e22fd7add5aed6f9f81d9023cca34a88.rrd], the file was never requested
    at org.jrobin.core.RrdDbPool.release(RrdDbPool.java:189) ~[jrobin-1.5.9.jar:1.5.9]
    at net.bull.javamelody.internal.model.JRobin.init(JRobin.java:227) ~[javamelody-core-1.88.0.jar:1.88.0]
    at net.bull.javamelody.internal.model.JRobin.<init>(JRobin.java:131) ~[javamelody-core-1.88.0.jar:1.88.0]
    at net.bull.javamelody.internal.model.JRobin.createInstance(JRobin.java:164) ~[javamelody-core-1.88.0.jar:1.88.0]   

Answer 1

It happens in a branch of the code when there exist empty rrd files in the javamelody storage directory, certainly because there is or there was no space left on device.

I suggest to check space left on device. And optionnaly delete empty rrd files, but if they are not deleted, javamelody is supposed to recreate correctly and automatically those empty rrd files when new data is collected for those rrd files, if there is free space on device of course.