Jelle Smits created ARTEMIS-4698:
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Summary: MetricsManagers' remove method may cause a
NullPointerException
Key: ARTEMIS-4698
URL: https://issues.apache.org/jira/browse/ARTEMIS-4698
Project: ActiveMQ Artemis
Issue Type: Bug
Affects Versions: 2.33.0, 2.32.0, 2.31.2, 2.31.1, 2.31.0, 2.30.0, 2.29.0,
2.28.0, 2.27.1, 2.27.0
Reporter: Jelle Smits
I recently switched from Artemis-server 2.19.1 to 2.31.1. From this point, I
have been experiencing a lot the following errors:
'AMQ224065: Failed to remove auto-created queue xyz'. The stack trace shows
that this consistenly happens in the 'remove' call of the MetricsManager. More
specifically, the 'logger.debug' statement which uses the 'removed' variable:
_java.lang.NullPointerException: Cannot invoke
"io.micrometer.core.instrument.Meter.getId()" because "removed" is null at
org.apache.activemq.artemis.core.server.metrics.MetricsManager.remove(MetricsManager.java:167)_
This did not happen in the previous version, as prior to
[ARTEMIS-4020|https://issues.apache.org/jira/browse/ARTEMIS-4020], the log
statement was conditional based on whether debug logging was enabled.
While the issue at hand may be caused by my application (un)registering
additional metrics on some queues, I feel the MeterRegistry should include a
null-check for the value of removed, as by the JavaDoc of Micrometers'
MeterRegistry, the meterRegistry.remove will return 'The removed meter, or null
if the provided meter is not currently registered.' Also, as a 'null' from the
MeterRegistry means that the metric no longer exists, as this is a remove call
that should not be a blocking issue.
I currently work around the issue using a class overload with an inline
nullcheck:
{{logger.debug("Unregistered meter: {}", removed != null ? removed.getId() :
"null");}}
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