On Thu, Dec 28, 2017 at 3:36 PM, Olaf Kock <tom...@olafkock.de> wrote: > > On 27.12.2017 23:16, Eric Robinson wrote: >>> >>> I mean A is java8 and tomcat8.. so make a C that is tomcat6 and java8 >> >> I don't think so. This is a requirement of the software company whose >> application solution we use. They are requiring us to move to tomcat 8 with >> jdk 1.8. If we try to mix tomcat8 with jdk 1.6, supposedly we would have >> problems. I guess all this is being driven by the need to switch to TLS 1.2. >> I'm not sure if that would be a function of tomcat or java. > > As you were looking for the reason of the increased footprint, this would > help you tremendously to get to the root cause, even if you don't intend to > use it in production. Assume that a similar behavior already appears when > you run tomcat6 with Java8 - in this case there might be little reason to > continue to dig in tomcat, and assume that it's the Java implementation that > caused your increased footprint. > > Tomcat 8 with Java 6 won't work (apart from the outdated implementation) as > it requires at least Java7 (which is also outdated). > > And then there's yet another aspect: The memory footprint increased way > below the price decrease for memory, so just adding this much memory could > be filed away as a reasonable assumption within 7.5 years (JDK 1.6.21 was > released July 2010, I'm assuming that this is the age of the hardware as > well (because why would you have installed this version on newer hardware, > when newer releases existed) > > I'm assuming that you have enough aspects to inspect - if you're really > interested in finding the root cause, you'll need to come up with more > specific measurements, e.g. profiler data, compare thread dumps and set up > Tomcat 6 with Java 8 to have a third reference point. > > Olaf >
How about turning on Native Memory Tracking for both Tomcat8+JDK1.8 and Tomcat6+JDK1.6 combination and compare the results? It will give you details about internal memory consumption of the JVM. If you see increase there, you will also able to find out which component's memory footprint has increased. You can turn NMT on by adding following JVM arguments: -XX:+UnlockDiagnosticVMOptions -XX:NativeMemoryTracking=summary After turning on NMT and running Tomcat, when you see there is rise in memory usage, use JCMD to dump native memory consumption details for analysis. You can find more details about NMT here: https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr007.html IMO, if you see there is not much difference between native memory consumption of JDK1.6 and JDK1.8, then you need to focus on Tomcat. Thanks! Suvendu --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
