On Thu, Jun 26, 2025 at 6:23 AM Rose Mary P T <rose.mary...@ibm.com> wrote: > > Dear Rémy Maucherat, > > > > Thank you for your comments. I have another question: can we configure both > virtual threads and platform threads in the same Apache Tomcat server.xml > file? Specifically, is it possible to set up one connector to support an > application using virtual threads, and another connector for a different > application using platform threads?
Yes, each connector gets its own "thread pool". > I would like to confirm whether this is a viable approach to make use of both > platform and virtual threads together > > <!-- configuraton for platform thread in 8081--> > > > > <Connector port="8081" protocol="HTTP/1.1" > > connectionTimeout="20000" > > redirectPort="8444" > > maxParameterCount="1000" > > /> > > > > <!-- configuraton for virtual thread in 8080--> > > <Executor name="tomcatExecutor" > className="org.apache.catalina.core.StandardVirtualThreadExecutor"/> > > <Connector port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol" > > connectionTimeout="18000" redirectPort="8443" > > executor="tomcatExecutor" > > useVirtualThreads="true"/> > I still think using <Executor> is redundant here, useVirtualThreads="true" is more than enough. Rémy > > > > Regards, > > Rose Mary > > > > From: Rémy Maucherat <r...@apache.org> > Date: Thursday, 19 June 2025 at 8:22 PM > To: Tomcat Users List <users@tomcat.apache.org> > Subject: [EXTERNAL] Re: Monitoring Virtual Threads via JMX / MBeans in Tomcat > > Hi, > > On Tue, May 20, 2025 at 12:57 PM Rose Mary P T > <rose.mary...@ibm.com.invalid> wrote: > > > > HI Mark, > > > > > > Just a gentle reminder regarding my previous message. I’m following up to > > see if there’s any update on this as its pending for long. > > > > As per your previous suggestion ,I was able to fetch the connectioncount. > > But the KeepAliveCount was always showing as zero. Given this behavior, I’m > > curious to know whether the formula: (connectionCount – keepAliveCount) > > > > Can we consider using ProtocolHandler.connectionCount to fetch the virtual > > threads created instead. > > > > Please let me know if you need any further information from my side. > > I investigated following your emails. Here are my comments: > - As Mark said, using an Executor for virtual threads is pointless. > Executor elements are used to share a single thread pool between > multiple NIO connectors, and since there's no pool, then there's no > point in using it. > - There was a missing flag in JMX for useVirtualThreads. The flag was > added recently, and was not added to the mbean. This is now fixed and > it will allow easily identifying a connector that uses virtual > threads. > - The keepAliveCount returned the wrong value for NIO. This is fixed. > > Let us know if you find other problems. > > Rémy > > > Looking forward to your response > > > > Regards, > > Rose Mary > > > > From: Rose Mary P T <rose.mary...@ibm.com.INVALID> > > Date: Tuesday, 20 May 2025 at 4:07 PM > > To: Tomcat Users List <users@tomcat.apache.org> > > Subject: [EXTERNAL] RE: Monitoring Virtual Threads via JMX / MBeans in > > Tomcat > > HI Mark, > > > > > > Just a gentle reminder regarding my previous message. I’m following up to > > see if there’s any update on this. Please let me know if you need any > > further information from my side. > > > > Looking forward to your response. > > > > > > > > Regards, > > > > Rose Mary > > > > > > From: Rose Mary P T <rose.mary...@ibm.com.INVALID> > > Date: Friday, 11 April 2025 at 7:08 PM > > To: Tomcat Users List <users@tomcat.apache.org>, ma...@apache.org > > <ma...@apache.org> > > Subject: [EXTERNAL] RE: Monitoring Virtual Threads via JMX / MBeans in > > Tomcat > > Dear Tomcat Users/Mark, > > I was finally able to retrieve the thread name from the workerThreadName > > attribute in RequestProcessor.tomcatExecutor for a request. In order to > > observe this, the request had to be long-running, which allowed JMX to > > capture the thread’s active state before it completed. > > However, I’ve observed that the keepAliveCount remains zero in this setup > > as well. Additionally, the connectionCount appears to reflect the number of > > incoming requests at that moment, but resets to 1 once the request has > > completed processing. > > Given this behavior, I’m curious to know whether the formula: > > (connectionCount – keepAliveCount) > > is still considered a reliable way to determine the number of virtual > > threads that are created or active at any point in time when using > > useVirtualThreads="true". > > I would appreciate any insights or clarifications on this. > > Thanks, > > Rose Mary > > > > > > From: Mark Thomas <ma...@apache.org> > > Date: Wednesday, 9 April 2025 at 4:12 PM > > To: users@tomcat.apache.org <users@tomcat.apache.org> > > Subject: [EXTERNAL] Re: Monitoring Virtual Threads via JMX / MBeans in > > Tomcat > > > > > > On 03/04/2025 13:05, Rose Mary P T wrote: > > > HI Mark, > > > > > > Thanks for your response. > > > > > > I would like to seek your guidance regarding an issue I am encountering > > > with my current Tomcat setup. Specifically, your recent suggestions > > > appear to contradict my existing configuration. Could you kindly confirm > > > whether the following executor and connector setup in Tomcat 10.1.36 is > > > correct? > > > > > > <Executor name="tomcatExecutor" namePrefix ="test" > > > className="org.apache.catalina.core.StandardVirtualThreadExecutor"/> > > > > > > <Connector port="8080" > > > protocol="org.apache.coyote.http11.Http11NioProtocol" > > > > > > connectionTimeout="18000" redirectPort="8443" > > > > > > executor="tomcatExecutor" > > > > > > useVirtualThreads="true"/> > > > > That should work. Although I do wonder on why you have configured an > > executor here. There isn't really any point with virtual threads. > > > > > In my setup, I am using *Http11NioProtocol* exclusively. However, I am > > > noticing the following: > > > > > > * *keepAliveCount* remains zero. > > > * *connectionCount* is consistently reported as 1. > > > > That suggests that the Tomcat instance isn't processing any requests. > > > > > * There is no visible value for |RequestProcessor#workerThreadName|. > > > Please see the screenshot : > > > > Screenshots don't work on the mailing list. Post it somewhere we can > > look at it. > > > > Mark > > > > > * > > > > > > I would greatly appreciate your insight into this matter, especially if > > > the configuration provided requires any adjustments or if there are > > > specific conditions I need to be aware of for the virtual threads to > > > function as expected. > > > > > > To clarify your previous question on the deployed application in > > > tomcat : This is a simple spring boot application which prints current > > > date in a loop of 100 > > > > > > Thank you for your time and assistance. I look forward to your response. > > > > > > Regards, > > > > > > Rose Mary > > > > > > *From: *Mark Thomas <ma...@apache.org> > > > *Date: *Thursday, 3 April 2025 at 2:49 PM > > > *To: *users@tomcat.apache.org <users@tomcat.apache.org> > > > *Subject: *[EXTERNAL] Re: Monitoring Virtual Threads via JMX / MBeans in > > > Tomcat > > > > > > On 28/03/2025 09:08, Rose Mary P T wrote: > > >> Hi Mark, > > >> Thank you for the confirmation. > > >> As per your suggestion, I have modified the deployed application so that > > >> it no longer spawns any threads but instead executes a few calls. > > > > > > Please clarify what you mean by "executes a few calls". > > > > > >> Additionally, I kept the previous executor and connection configurations > > >> for Tomcat. However, I still do not see any noticeable changes in the > > >> keepAliveCount attribute. The connectionCount currently shows a value of > > >> 1. > > >> At this point, I'm unsure of the next troubleshooting steps or what > > >> specific aspects to investigate further. Any guidance on what to focus > > >> on next would be greatly appreciated. > > >> Additionally, could you suggest if there is any MBean attribute that can > > >> help identify whether the threads being used are virtual threads or > > >> platform threads? > > > > > > For Tomcat requests, the current thread name includes "virt" if it is a > > > virtual thread. Look at RequestProcessor#workerThreadName for one place > > > to see the thread names used for requests > > > > > > With NIO2, keepAliveCount will always be -1 as it isn't tracked. > > > Switching to NIO would make keepAliveCount available. > > > > > > connectionCount will always be 1 more than the current connections. i.e. > > > a value of 1 means there are no current requests. > > > > > > Mark > > > > > > > > >> Thank you for your continued support. > > >> > > >> Best Regards, > > >> Rose Mary > > >> > > >> > > >> From: Mark Thomas <ma...@apache.org> > > >> Date: Thursday, 27 March 2025 at 9:25 PM > > >> To: users@tomcat.apache.org <users@tomcat.apache.org> > > >> Subject: [EXTERNAL] Re: Monitoring Virtual Threads via JMX / MBeans in > > >> Tomcat > > >> On 26/03/2025 10:38, Rose Mary P T wrote: > > >>> Dear Tomcat Users, > > >>> I hope this message finds you well. > > >>> As per your previous email, we attempted to fetch the virtual thread > > >>> count from the keepAliveCount attribute in the Catalina.ThreadPool > > >>> MBean. > > >>> For context, here is the setup we used: > > >>> > > >>> * We created a sample Spring Boot application that continuously > > >>> creates virtual threads in a loop. > > >> > > >> If the application is creating the threads then this won't work. The > > >> (connectionCount - keepAliveCount) approach only works for virtual > > >> threads created by Tomcat for processing requests. > > >> > > >> If the application is creating the virtual threads then I'd suggest > > >> adding tracking for the current number of virtual threads to the > > >> application. > > >> > > >> Mark > > >> > > >>> * The application was deployed in the TOMCAT_LOCATION/webapps > > >>> directory and started on localhost. > > >>> In Apache Tomcat 10.1.36, we added the following configuration to the > > >>> server.xml file to enable virtual threads: > > >>> <Executor name="tomcatExecutor" > > >>> className="org.apache.catalina.core.StandardVirtualThreadExecutor"/> > > >>> <Connector port="8080" > > >>> protocol="org.apache.coyote.http11.Http11NioProtocol" > > >>> connectionTimeout="18000" redirectPort="8443" > > >>> executor="tomcatExecutor" > > >>> useVirtualThreads="true"/> > > >>> > > >>> Its observed in the logs that virtual threads were being created as > > >>> expected. However, we noticed that the keepAliveCount attribute in the > > >>> Catalina.ThreadPool MBean is showing a value of 0, even though virtual > > >>> threads are being spawned. > > >>> It seems that the keepAliveCount attribute does not provide a valid > > >>> value for counting the virtual threads. We were wondering if this is > > >>> expected behavior, or if there is a different way to monitor the > > >>> virtual threads created in Tomcat. > > >>> We would also like to know if there's a way to differentiate between > > >>> platform threads and virtual threads using any MBean attribute in the > > >>> Catalina service or elsewhere in Tomcat's MBean architecture. > > >>> We would greatly appreciate any guidance or insights you can provide > > >>> regarding this issue. > > >>> Best Regards, > > >>> Rose Mary > > >>> > > >>> > > >>> > > >>> From: Joash Jose <joash.j...@ibm.com> > > >>> Date: Wednesday, 26 March 2025 at 12:48 PM > > >>> To: Rose Mary P T <rose.mary...@ibm.com> > > >>> Subject: <no subject> > > >>> > > >>> > > >>> > > >>> Begin forwarded message: > > >>> > > >>> From: Mark Thomas <ma...@apache.org> > > >>> Subject: [EXTERNAL] Re: Monitoring Virtual Threads via JMX / MBeans in > > >>> Tomcat > > >>> Date: 6 March 2025 at 2:08:43 PM IST > > >>> To: <users@tomcat.apache.org> > > >>> Reply-To: "Tomcat Users List" <users@tomcat.apache.org> > > >>> > > >>> On 06/03/2025 06:29, Joash Jose wrote: > > >>> > > >>> Dear Apache Tomcat Support Team, > > >>> I hope this message finds you well. > > >>> I am writing to inquire whether Apache Tomcat (tomacat version is > > >>> 10.1.33 running on Java 21) exposes virtual thread metrics through JMX > > >>> / MBeans. Specifically: > > >>> Virtual Thread Visibility: > > >>> Does Tomcat provide MBeans (e.g., under Catalina:type=Executor) to > > >>> monitor virtual thread usage, such as active virtual thread counts, > > >>> creation rate, or parking states? > > >>> > > >>> No with a few caveats - see below). > > >>> > > >>> > > >>> If not, are there plans to add such metrics in future releases? > > >>> > > >>> No. > > >>> > > >>> > > >>> Or any alternate ways with which we can monitor this from tomcat side.? > > >>> > > >>> (connectionCount - keepAliveCount) should be a reasonable estimate of > > >>> the virtual threads currently being used. > > >>> > > >>> If the requests are synchronous (and there is little point using > > >>> virtual threads with async requests) then the creation rate is > > >>> derivable from the requestCount in the GlobalRequestProcessor. > > >>> > > >>> There is no information on parking states. > > >>> > > >>> > > >>> Configuration Clarification: > > >>> We have configured Tomcat 10.1.33 with, > > >>> <Executor name="tomcatThreadPool" > > >>> className="org.apache.catalina.core.StandardVirtualThreadExecutor"/> > > >>> <Connector port="8080" > > >>> protocol="org.apache.coyote.http11.Http11Nio2Protocol" > > >>> connectionTimeout="18000" socket.soTimeout="18000" redirectPort="8443" > > >>> enableLookups="false" URIEncoding="UTF-8" compression="on" > > >>> useVirtualThreads="true" server="ARandomServer"/> > > >>> > > >>> The <Executor .../> element isn't being used. Why configure it? > > >>> > > >>> > > >>> While this works, the existing ThreadPool MBeans show > > >>> currentThreadsBusy=-1 and maxThreads=200 (incorrect in case of virtual > > >>> threads). Is this expected behavior? > > >>> > > >>> Yes. > > >>> > > >>> > > >>> JVM vs. Tomcat Metrics: > > >>> We observe that the JVM’s java.lang.management.ThreadMXBean includes > > >>> virtual threads, but this aggregates data across all applications on > > >>> the JVM. Does Tomcat offer a way to isolate virtual thread metrics > > >>> specific to Tomcat? > > >>> > > >>> No, because the JVM doesn't provide a mechanism to have multiple > > >>> pools/groups/anything of virtual threads. > > >>> > > >>> Mark > > >>> > > >>> > > >>> --------------------------------------------------------------------- > > >>> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > > >>> For additional commands, e-mail: users-h...@tomcat.apache.org > > >>> Begin forwarded message: > > >>> > > >>> From: Joash Jose <joash.j...@ibm.com> > > >>> Subject: Monitoring Virtual Threads via JMX / MBeans in Tomcat > > >>> Date: 6 March 2025 at 11:59:29 AM IST > > >>> To: <d...@tomcat.apache.org>, <users@tomcat.apache.org> > > >>> > > >>> Dear Apache Tomcat Support Team, > > >>> > > >>> I hope this message finds you well. > > >>> > > >>> I am writing to inquire whether Apache Tomcat (tomacat version is > > >>> 10.1.33 running on Java 21) exposes virtual thread metrics through JMX > > >>> / MBeans. Specifically: > > >>> > > >>> Virtual Thread Visibility: > > >>> > > >>> Does Tomcat provide MBeans (e.g., under Catalina:type=Executor) to > > >>> monitor virtual thread usage, such as active virtual thread counts, > > >>> creation rate, or parking states? > > >>> If not, are there plans to add such metrics in future releases? > > >>> Or any alternate ways with which we can monitor this from tomcat side.? > > >>> > > >>> Configuration Clarification: > > >>> We have configured Tomcat 10.1.33 with, > > >>> <Executor name="tomcatThreadPool" > > >>> className="org.apache.catalina.core.StandardVirtualThreadExecutor"/> > > >>> <Connector port="8080" > > >>> protocol="org.apache.coyote.http11.Http11Nio2Protocol" > > >>> connectionTimeout="18000" socket.soTimeout="18000" redirectPort="8443" > > >>> enableLookups="false" URIEncoding="UTF-8" compression="on" > > >>> useVirtualThreads="true" server="ARandomServer"/> > > >>> While this works, the existing ThreadPool MBeans show > > >>> currentThreadsBusy=-1 and maxThreads=200 (incorrect in case of virtual > > >>> threads). Is this expected behavior? > > >>> > > >>> JVM vs. Tomcat Metrics: > > >>> We observe that the JVM’s java.lang.management.ThreadMXBean includes > > >>> virtual threads, but this aggregates data across all applications on > > >>> the JVM. Does Tomcat offer a way to isolate virtual thread metrics > > >>> specific to Tomcat? > > >>> > > >>> Regards, > > >>> Joash > > >>> Begin forwarded message: > > >>> > > >>> From: Joash Jose <joash.j...@ibm.com.INVALID> > > >>> Subject: [EXTERNAL] Monitoring Virtual Threads via JMX / MBeans in > > >>> Tomcat > > >>> Date: 6 March 2025 at 11:59:40 AM IST > > >>> To: "d...@tomcat.apache.org" <d...@tomcat.apache.org>, > > >>> "users@tomcat.apache.org" <users@tomcat.apache.org> > > >>> Reply-To: "Tomcat Users List" <users@tomcat.apache.org> > > >>> > > >>> Dear Apache Tomcat Support Team, > > >>> > > >>> I hope this message finds you well. > > >>> > > >>> I am writing to inquire whether Apache Tomcat (tomacat version is > > >>> 10.1.33 running on Java 21) exposes virtual thread metrics through JMX > > >>> / MBeans. Specifically: > > >>> > > >>> Virtual Thread Visibility: > > >>> > > >>> Does Tomcat provide MBeans (e.g., under Catalina:type=Executor) to > > >>> monitor virtual thread usage, such as active virtual thread counts, > > >>> creation rate, or parking states? > > >>> If not, are there plans to add such metrics in future releases? > > >>> Or any alternate ways with which we can monitor this from tomcat side.? > > >>> > > >>> Configuration Clarification: > > >>> We have configured Tomcat 10.1.33 with, > > >>> <Executor name="tomcatThreadPool" > > >>> className="org.apache.catalina.core.StandardVirtualThreadExecutor"/> > > >>> <Connector port="8080" > > >>> protocol="org.apache.coyote.http11.Http11Nio2Protocol" > > >>> connectionTimeout="18000" socket.soTimeout="18000" redirectPort="8443" > > >>> enableLookups="false" URIEncoding="UTF-8" compression="on" > > >>> useVirtualThreads="true" server="ARandomServer"/> > > >>> While this works, the existing ThreadPool MBeans show > > >>> currentThreadsBusy=-1 and maxThreads=200 (incorrect in case of virtual > > >>> threads). Is this expected behavior? > > >>> > > >>> JVM vs. Tomcat Metrics: > > >>> We observe that the JVM’s java.lang.management.ThreadMXBean includes > > >>> virtual threads, but this aggregates data across all applications on > > >>> the JVM. Does Tomcat offer a way to isolate virtual thread metrics > > >>> specific to Tomcat? > > >>> > > >>> Regards, > > >>> Joash > > >>> --------------------------------------------------------------------- > > >>> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > > >>> For additional commands, e-mail: users-h...@tomcat.apache.org > > >>> > > >> > > >> > > >> --------------------------------------------------------------------- > > >> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > > >> For additional commands, e-mail: users-h...@tomcat.apache.org > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > > > For additional commands, e-mail: users-h...@tomcat.apache.org > > > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > > For additional commands, e-mail: users-h...@tomcat.apache.org > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
