I am having trouble with Tomcat 9, openjdk 126.96.36.199 on ubuntu 18.04. I installed it using these instructions: https://linuxize.com/post/how-to-install-tomcat-9-on-ubuntu-18-04/
It worked fine for a while, but today when I try to go to any application or any of the Tomcat manager pages, my browser hangs. The service has not been restarted in the interim. I find nothing of interest in any of the Tomcat logs.
I tried "systemctl status tomcat", and I see Tasks is 35 with a limit of 37. It worries me that there appears to be almost no headroom.
So three questions:
What are Tasks? Are they Threads? Processes? Something else?
Where do the 35 and 37 come from? Is the 37 based on the size of my server (which is admittedly small right now)?
Is it reasonable that my Tomcat hang might be related to this?
Sample systemctl status output (note that the uptime you see here reflects the fact that I have since tried restarting the service, with no improvement):
# systemctl status tomcat ● tomcat.service - Tomcat 9 servlet container Loaded: loaded (/etc/systemd/system/tomcat.service; enabled; vendor preset: enabled) Active: active (running) since Thu 2021-02-04 14:18:27 PST; 40min ago Process: 194 ExecStart=/opt/tomcat/latest/bin/startup.sh (code=exited, status=0/SUCCESS) Main PID: 212 (java) Tasks: 35 (limit: 37) CGroup: /system.slice/tomcat.service └─212 /usr/lib/jvm/java-1.11.0-openjdk-amd64/bin/java -Djava.util.logging.config.file=/opt/tomcat/latest/conf/logging.pro Feb 04 14:18:16 cloud.wolfeld.com shutdown.sh: /opt/tomcat/latest/bin/catalina.sh: 574: /opt/tomcat/latest/bin/catalina.sh: C Feb 04 14:18:16 cloud.wolfeld.com systemd: tomcat.service: Main process exited, code=exited, status=143/n/a Feb 04 14:18:16 cloud.wolfeld.com systemd: tomcat.service: Control process exited, code=exited status=2 Feb 04 14:18:16 cloud.wolfeld.com systemd: tomcat.service: Failed with result 'exit-code'. Feb 04 14:18:16 cloud.wolfeld.com systemd: Stopped Tomcat 9 servlet container. Feb 04 14:18:27 cloud.wolfeld.com systemd: Starting Tomcat 9 servlet container... Feb 04 14:18:27 cloud.wolfeld.com startup.sh: Existing PID file found during start. Feb 04 14:18:27 cloud.wolfeld.com startup.sh: Removing/clearing stale PID file. Feb 04 14:18:27 cloud.wolfeld.com startup.sh: Tomcat started. Feb 04 14:18:27 cloud.wolfeld.com systemd: Started Tomcat 9 servlet container.