On Tue, Feb 11, 2020, 18:40 James H. H. Lampert <jam...@touchtonecorp.com> wrote:
> Ladies and Gentlemen: > > We have a customer installation in which the JVM job for our Tomcat > server is frequently using massive amounts of CPU. > > It's Tomcat 7.0.67, running on an AS/400, in a 64-bit Java 7 JVM, with > -Xms3096m and -Xmx5120m JVM arguments. > > GC information on the JVM job shows: > > Garbage collected heap: > > Initial heap size . . . . . . . . . : 3096.000M > > Maximum heap size . . . . . . . . . : 5120.000M > > Current heap size . . . . . . . . . : 4458.562M > > Heap in use . . . . . . . . . . . . : 1907.673M > > Other memory: > > Internal (break) memory size . . . . : 504.982M > > JIT memory size . . . . . . . . . . : 74.000M > > Shared classes memory size . . . . . : 0.000M > > General GC information: > > Current GC cycle . . . . . . . . . . : 2184 > > GC policy type . . . . . . . . . . . : GENCON > > Current GC cycle time . . . . . . . : 552 > > Accumulated GC time . . . . . . . . : 5108241 > > It seems to be doing a lot of garbage-collecting. > > Would switching to Java 8 help? Would switching to 7.0.93 help? Well, End of Public Updates for Java 7 was Apr 2015 (Extended support to 2022). EOPU for Java 8 was Jan 2019 (Ext support to 2025). Is this a new client install? Or has the app been running with no issue until some time recently? Does the issue surface with one user; or 20 users; or 100 users? How many instances of Tomcat? (on the same machine?) Have y'all run a profiler (JVisualVM or Mission Control or YourKit, etc) to narrow down where in the app it's spiking and to gather more granular GC stats? It's always my experience these type of issues are not Tomcat, it's the app, or something's misconfigured.
