For performance reasons, JGroups caches log levels as follows:

boolean trace=log.isTraceEnabled();

// later:
if(trace) {
log.trace(...);
}

While caching created a measurable performance increase, it also disabled the ability to change the log levels at runtime (example: JBoss' log4j.xml, which is re-read every 60 secs).

Investigate how to have both good performance and dynamic runtime configuration of log levels. E.g. signal to enable logging ?