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Posted to dev@tomcat.apache.org by "adj5672 (via GitHub)" <gi...@apache.org> on 2026/01/06 04:11:51 UTC
[PR] Add virtual thread attribute to WsWebSocketContainer [tomcat]
adj5672 opened a new pull request, #936:
URL: https://github.com/apache/tomcat/pull/936
In my app, I use WsWebSocketContainer to create websocket client.
When session count increase the more, memory usage also increased. So OOM Killed occured frequently.
I know that It is a normal situation in thread per connection model which is current applied.
Current model have advantage that It is very intuitive and sometimes it behaves like kind of rate limiter.
But I think that thread for RW task may not working busy in some case.
Also platform thread will be created twice of session count and it allocate a lot of default stack memory.
furthermore context switching cost expensive too when using platform thread.
So I think that instead of create two platform thread per session, using virtual thread will be helpful to memory optimization.
Since I may not understand overall about websocket codes and architecture, I just create draft pull request.
The point is optimizing memory usage even if virtual thread isn't.
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Re: [PR] Add virtual thread attribute to WsWebSocketContainer [tomcat]
Posted by "VolareYang (via GitHub)" <gi...@apache.org>.
VolareYang commented on PR #936:
URL: https://github.com/apache/tomcat/pull/936#issuecomment-4776775942
Hi! I have a question: how do I enable virtual threads in Tomcat 11? After enabling virtual threads, which log in Tomcat's startup logs can I check to confirm that virtual threads are actually being used?
My environment:
Tomcat: 11.0.23
JDK: 21
server.xml configuration:
<Executor name="virtualThreadExecutor" className="org.apache.catalina.core.StandardVirtualThreadExecutor" namePrefix="tomcat-virt-"/>
<Connector executor="virtualThreadExecutor" port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" />
Startup logs show:
23-Jun-2026 14:51:39.306 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["http-nio-8080"]
23-Jun-2026 14:51:39.313 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in [799] milliseconds
When I check the thread stack with the jstack command, I don't see any threads related to tomcat-virt- so I can't be sure if virtual threads are actually enabled. Could you guide me? Thanks!
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