Github user anew commented on a diff in the pull request: https://github.com/apache/twill/pull/14#discussion_r86274401 --- Diff: twill-api/src/main/java/org/apache/twill/api/TwillController.java --- @@ -89,4 +90,44 @@ * @return A {@link Future} that will be completed when the restart operation has been done. */ Future<String> restartInstances(String runnable, int instanceId, int... moreInstanceIds); + + /** + * Set the root log level for Twill applications in all containers. + * + * @param logLevel The log level for the root logger to change. + * @return A {@link Future} that will be completed when the set log level operation has been done. It will carry + * the log level as a result. + */ + Future<LogEntry.Level> setRootLogLevel(LogEntry.Level logLevel); + + /** + * Set the root log level for a particular runnable. + * + * @param runnableName The name of the runnable to set the log level. + * @param logLevel The log level for the root logger to change. + * @return A {@link Future} that will be completed when the set log level operation has been done. It will carry + * the log level as a result. + */ + Future<LogEntry.Level> setRootLogLevel(String runnableName, LogEntry.Level logLevel); --- End diff -- question about race conditions. Suppose I have an app that has N runnables, and I set them all to DEBUG because there was a problem. Now I have identified which runnable is the culprit, so I want to reset all others to WARN and the suspicious one to TRACE. It looks like, for this, I need to make two calls: ``` setRootLogLevel(WARN); setRootLogLevel("suspiciousRunnable", TRACE); ``` The suspicious runnable will be affected by both calls. Is it guaranteed that after all, it will be on TRACE? That is, the order of calls is preserved? Or what would be the correct way to do this?
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