+1 cool!
On Wed, May 9, 2018 at 7:59 AM, Norbert Kalmar <[email protected]> wrote: > Okay, thanks Ed, I created the Jira, will look into it soon :) > https://issues.apache.org/jira/browse/ZOOKEEPER-3037 > > Regards, > Norbert > > On Wed, May 9, 2018 at 4:44 PM Edward Ribeiro <[email protected]> > wrote: > > > +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 <[email protected]> > > 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 > > > > > >
