ContextLoader - Root WebApplicationContext initialized 3 times on ubuntu tomcat

Question

Dears, I have a jersey - spring api deployed on apache tomcat 9.0.46. (Jersey to handle restful services JAX-RS and Spring to handle all my beans{controllers, DAO, SessionFactory, JPA etc...}). Everything works fine on tomcat 9 on windows... When deploying the exact same war in ubuntu tomcat 9.0.46, the ContextLoader is getting triggered 3 times and I have all my singletons instantiated 3 times. I'm deploying the api on tomcat ports 80 and 443 (https - godady certificate). once I start tomcat the war is deployed and ports 80 and 443 get started (netstat -tulnp | grep java) and I see in log all singletons instantiated. (pool-2) Applicationcontext class my custom spring @Configuration class and it is getting triggered and DB is accessed without any issues

2021-06-09 14:41:52,128 1104 [main] INFO  o.s.web.context.ContextLoader - Root WebApplicationContext initialized in 905 ms
2021-06-09 14:41:53,124 2100 [pool-2-thread-1] INFO  skd.app.core.ApplicationContext - TASK::cleanExpiredStatuses

then the server takes few minutes (around 10 minutes 14:41 above then 14:51 below) and when port 8005 is started I see again the ContextLoader is triggered again 2 times.

09-Jun-2021 14:51:36.196 WARNING [main] org.apache.catalina.util.SessionIdGeneratorBase.createSecureRandom Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [584,064] milliseconds.
09-Jun-2021 14:51:36.592 INFO [main] org.glassfish.jersey.server.ApplicationHandler.initialize Initiating Jersey application, version Jersey: 2.6 2014-02-18 21:52:53...
09-Jun-2021 14:51:37.042 INFO [main] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [/opt/apache-tomcat-9.0.46/webapps/skd-service.war] has finished in [588,185] ms

2021-06-09 14:51:39,388 696  [main] INFO  o.s.web.context.ContextLoader - Root WebApplicationContext initialized in 581 ms
09-Jun-2021 14:51:39.632 INFO [main] org.glassfish.jersey.server.ApplicationHandler.initialize Initiating Jersey application, version Jersey: 2.6 2014-02-18 21:52:53...
09-Jun-2021 14:51:40.013 INFO [main] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [/opt/apache-tomcat-9.0.46/webapps/skd-service.war]

and again for the 3rd time:

2021-06-09 14:51:41,989 744  [main] INFO  o.s.web.context.ContextLoader - Root WebApplicationContext initialized in 605 ms
09-Jun-2021 14:51:42.232 INFO [main] org.glassfish.jersey.server.ApplicationHandler.initialize Initiating Jersey application, version Jersey: 2.6 2014-02-18 21:52:53...
09-Jun-2021 14:51:42.602 INFO [main] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [/opt/apache-tomcat-9.0.46/webapps/skd-service.war] has finished in [2,590] ms

Everything is working fine in windows, only when deploying to ubuntu tomcat, I'm getting this. Does anyone have a clue why this difference in tomcat behaviour between windows and ubuntu for the same exact WAR file?

Answer 1

I have managed to figure out the problem. The issue was related to tomcat configuration in /conf/server.xml. Multiple Hosts will trigger the context loader to be triggered for each. I was keeping the default appBase to webapps for all host thus triggering the ContextLoader of each my war for each host. Another reason the ContextLoader will triggered multiple times as well is defining the option inside unless you need to load something external to your war. I recommend reading specs: https://tomcat.apache.org/tomcat-4.1-doc/config/host.html