+1. Sounds really nice to have feature. Let's open a ticket and open a PR. :)
Ed Em qua, 9 de mai de 2018 11:15, Norbert Kalmar <nkal...@cloudera.com> escreveu: > Hi, > > I just got a tip that we could improve on the logging in ZooKeeper. After a > ZK crash, or client timeout sometimes it's hard to determine from the logs > what happened. Knowing if ZK was responsive at the time would help a lot. > For example, ZK might spend a lot of time waiting on GC (there is still > some misconception that ZK is a storage). > > To help detect this, HADOOP already has a great tool called JVM Pause > Monitor. (As the name suggest, it can be also used for monitoring, but it > also helps post-mortem in a lot of cases). Basically it has a daemon that > sleeps for one second, and if the sleep time exceeds the 1s by more than > the threshold (1s: INFO, 10s: WARN by default - this can be configurable in > our case, see below), it will alert/make a log entry. It can also monitor > the time GC took. > > Now, this class is in the HADOOP-common. I wouldn't want to depend on > Hadoop-common because of this one feature/class (it is actually a single > class). Since this is a straightforward implementation, and in the past > five years the few commits it had is nothing really serious, I think we > could just copy this class in ZooKeeper, and introduce it as a configurable > feature, by default it can be off. > > The class: > > https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/JvmPauseMonitor.java > > What do You think? > > Regards, > Norbert >
