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
