Hello, First of all: Christopher Schultz: You answered an email from me 6 weeks ago. You helped me a lot with your suggestions. I have done a lot of research and have learnt a lot since then, so I have been able to rule out a lot of potential roots for my issue. Because of that I am able to post a new more specific email. Thanks a lot!!!
Now, this is my stack: - Ubuntu 22.04.3 on x86/64 with 2GM of physical RAM that has been enough for years. - Java 11.0.20.1+1-post-Ubuntu-0ubuntu122.04 / openjdk 11.0.20.1 2023-08-24 - Tomcat 9.0.58 (JAVA_OPTS="-Djava.awt.headless=true -Xmx1000m -Xms1000m ......") - My app, which I developed myself, and has been running without any problems for years Well, a couple of months ago my website/Tomcat/Java started eating more and more memory about after about 4-7 days. The previous days it uses just a few hundred MB and is very steady, but then after a few days the memory usage suddenly grows up to 1.5GB (and then stops growing at that point, which is interesting). Between these anomalies the RAM usage is fine and very steady (as it has been for years) and it uses just about 40-50% of the "Max memory" (according to what the Tomcat Manager server status shows). The 3 components of G1GC heap memory are steady and low, before and after the usage grows to 1.5GB, so it is definitely not that the heap starts requiring more and more memory. I have been using several tools to monitor that (New Relic, VisualVM and JDK Mission Control) so I'm sure that the memory usage by the heap is not the problem. The Non-heaps memory usage is not the problem either. Everything there is normal, the usage is humble and even more steady. And there are no leaks, I'm sure of that. I have inspected the JVM using several tools. There are no peaks in the number of threads either. The peak is the same when the memory usage is low and when it requires 1.5GB. It stays the same all the time. I have also reviewed all the scheduled tasks in my app and lowered the amount of objects they create, which was nice and entertaining. But that is not the problem, I have analyzed the object creation by all the threads (and there are many) and the threads created by my scheduled tasks are very humble in their memory usage, compared to many other threads. And I haven't made any relevant changes to my app in the 6-12 months before this problem started occurring. It is weird that I started having this problem. Could it be that I received an update in the java version or the Tomcat version that is causing this problem? If neither the heap memory or the Non-heaps memory is the source of the growth of the memory usage, what could it be? Clearly something is happening inside the JVM that raises the memory usage. And everytime it grows, it doesn't decrease. It is like if something suddenly starts "pushing" the memory usage more and more, until it stops at 1.5GB. I think that maybe the source of the problem is the garbage collector. I haven't used any of the switches that we can use to optimize that, basically because I don't know what I should do there (if I should at all). I have also activated the GC log, but I don't know how to analyze it. I have also increased and decreased the value of "-Xms" parameter and it is useless. Finally, maybe I should add that I activated 4GB of SWAP memory in my Ubuntu instance so at least my JVM would not be killed my the OS anymore (since the real memory is just 1.8GB). That worked and now the memory usage can grow up to 1.5GB without crashing, by using the much slower SWAP memory, but I still think that this is an abnormal situation. Thanks in advance for your suggestions!
