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https://reviews.apache.org/r/55591/
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Review request for geode, Bruce Schuchardt, Darrel Schneider, Jinmei Liao,
Jared Stewart, and Kevin Duling.
Bugs: GEODE-2297
https://issues.apache.org/jira/browse/GEODE-2297
Repository: geode
Description
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GEODE-2297: passively discover DistributedSystem instance in AlertAppender to
use in append
AlertAppender was actively hitting a synchronization and fetching
InternalDistributedSystem singleton in every append(!) call. This can produce a
deadlock if an alert is generated during startup.
This change removes the active fetch from the append code path and uses
InternalDistributedSystem.ConnectListener and
InternalDistributedSystem.DisconnectListener to receive notifications of
connect and disconnect. These notifications set an AtomicReference that is now
checked within append. (Registering a ConnectListener is static and remains
registered for the life of the JVM. For every onConnect, the AlertAppender
registers a non-static DisconnectListener for each InternalDistributedSystem
instance.)
I also fixed some minor IDE warnings, changed a logger statement from info to
debug and added a TODO to the class' logger instance. I want to follow up later
to *probably* change from using Logger to StatusLogger. Note: we run with
StatusLogger level of FATAL by default. Appender impl's really should use
StatusLogger instead of Logger (to avoid risk of infinite looping). As it's
currently written (with Logger), you'd have to set the AlertLevel to DEBUG to
hit this problem. I believe someone would only do this by error or for
experimentation.
Diffs
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geode-core/src/main/java/org/apache/geode/internal/logging/log4j/AlertAppender.java
a6c54aba352ba4dd3ece94c94f770292db6e9284
Diff: https://reviews.apache.org/r/55591/diff/
Testing
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precheckin in progress
Thanks,
Kirk Lund
