1. 1. 1. Description of problem:

It seems that H2MinWorkers and H2MaxWorkerIdleSeconds do not work.
And it looks to me that the following commit changed the behavior:

trunk: https://github.com/apache/httpd/commit/e78889fcb6599e2c353f4bcfeb44aa9c598794a7
2.4.x: https://github.com/apache/httpd/commit/2f8392ad9d821109e941773712bcf8e54ba0a3ce

CHANGES log says "There are H2MaxWorkers threads created at start and the number is kept constant for now".
So, the number of threads is always fixed (created at start-up and never reclaimed). It looks the behavior is changed intentionally for better performance.

~~~
*) mod_http2: h2 workers with improved scalability for better scheduling
performance. There are H2MaxWorkers threads created at start and the
number is kept constant for now. [Stefan Eissing]
~~~

1. 1. 1. Version-Release number of selected component (if applicable):

httpd-2.4.37-11.module+el8.0.0+2969+90015743.x86_64

1. 1. 1. How reproducible:

anytime

1. 1. 1. Steps to Reproduce:
         1: yum install httpd-2.4.37-11.module+el8.0.0+2969+90015743.x86_64

2: vim /etc/httpd/conf/httpd.conf (Please see attachement for details)

#cat httpd.conf
Protocols h2 h2c http/1.1

StartServers 1
MinSpareThreads 1
MaxSpareThreads 1
ThreadLimit 1
ThreadsPerChild 1
MaxRequestWorkers 1
MaxConnectionsPerChild 0

H2MaxWorkerIdleSeconds 10

H2MaxWorkers 10
H2MinWorkers 2
....snip....

3:systemctl start httpd

1. 1. 1. Actual results:
         Even if 10 seconds(=H2MaxWorkerIdleSeconds) or more passes, it does not become H2MinWorkers value.

1. ps auxww -L | grep -e mysqld -e httpd -e NLWP | grep -v grep
   USER PID LWP %CPU NLWP %MEM VSZ RSS TTY STAT START TIME COMMAND
   root 5936 5936 0.8 1 0.3 96192 6656 ? Ss 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5938 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5939 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5940 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5941 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5942 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5943 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5945 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND
   apache 5938 5946 0.0 8 0.2 305560 4912 ? Sl 10:35 0:00 /usr/sbin/httpd -DFOREGROUND

1. pstack 5938
   Thread 8 (Thread 0x7fd285381700 (LWP 5946)):
   #0 0x00007fd28dd73d97 in epoll_wait () from target:/lib64/libc.so.6
   #1 0x00007fd28e48672a in impl_pollset_poll () from target:/lib64/libapr-1.so.0
   #2 0x00007fd28c199592 in listener_thread () from target:/etc/httpd/modules/mod_mpm_event.so
   #3 0x00007fd28e2472de in start_thread () from target:/lib64/libpthread.so.0
   #4 0x00007fd28dd73a63 in clone () from target:/lib64/libc.so.6
   Thread 7 (Thread 0x7fd285b82700 (LWP 5945)):
   #0 0x00007fd28e24d48c in pthread_cond_wait@@GLIBC_2.3.2 () from target:/lib64/libpthread.so.0
   #1 0x00005576b1e544bd in ap_queue_pop_something ()
   #2 0x00007fd28c19900a in worker_thread () from target:/etc/httpd/modules/mod_mpm_event.so
   #3 0x00007fd28e2472de in start_thread () from target:/lib64/libpthread.so.0
   #4 0x00007fd28dd73a63 in clone () from target:/lib64/libc.so.6
   Thread 6 (Thread 0x7fd286b84700 (LWP 5943)):
   #0 0x00007fd28e24d48c in pthread_cond_wait@@GLIBC_2.3.2 () from target:/lib64/libpthread.so.0
   #1 0x00007fd28b96fb52 in slot_run () from target:/etc/httpd/modules/mod_http2.so
   #2 0x00007fd28e2472de in start_thread () from target:/lib64/libpthread.so.0
   #3 0x00007fd28dd73a63 in clone () from target:/lib64/libc.so.6
   Thread 5 (Thread 0x7fd287385700 (LWP 5942)):
   #0 0x00007fd28e24d48c in pthread_cond_wait@@GLIBC_2.3.2 () from target:/lib64/libpthread.so.0
   #1 0x00007fd28b96fb52 in slot_run () from target:/etc/httpd/modules/mod_http2.so
   #2 0x00007fd28e2472de in start_thread () from target:/lib64/libpthread.so.0
   #3 0x00007fd28dd73a63 in clone () from target:/lib64/libc.so.6
   Thread 4 (Thread 0x7fd287b86700 (LWP 5941)):
   #0 0x00007fd28e24d48c in pthread_cond_wait@@GLIBC_2.3.2 () from target:/lib64/libpthread.so.0
   #1 0x00007fd28b96fb52 in slot_run () from target:/etc/httpd/modules/mod_http2.so
   #2 0x00007fd28e2472de in start_thread () from target:/lib64/libpthread.so.0
   #3 0x00007fd28dd73a63 in clone () from target:/lib64/libc.so.6
   Thread 3 (Thread 0x7fd288387700 (LWP 5940)):
   #0 0x00007fd28e24d48c in pthread_cond_wait@@GLIBC_2.3.2 () from target:/lib64/libpthread.so.0
   #1 0x00007fd28b96fb52 in slot_run () from target:/etc/httpd/modules/mod_http2.so
   #2 0x00007fd28e2472de in start_thread () from target:/lib64/libpthread.so.0
   #3 0x00007fd28dd73a63 in clone () from target:/lib64/libc.so.6
   Thread 2 (Thread 0x7fd288b88700 (LWP 5939)):
   #0 0x00007fd28e24d48c in pthread_cond_wait@@GLIBC_2.3.2 () from target:/lib64/libpthread.so.0
   #1 0x00007fd28b96fb52 in slot_run () from target:/etc/httpd/modules/mod_http2.so
   #2 0x00007fd28e2472de in start_thread () from target:/lib64/libpthread.so.0
   #3 0x00007fd28dd73a63 in clone () from target:/lib64/libc.so.6
   Thread 1 (Thread 0x7fd28f66d900 (LWP 5938)):
   #0 0x00007fd28e250b44 in read () from target:/lib64/libpthread.so.0
   #1 0x00005576b1e5364b in ap_mpm_podx_check ()
   #2 0x00007fd28c1968f7 in child_main () from target:/etc/httpd/modules/mod_mpm_event.so
   #3 0x00007fd28c196c2a in make_child () from target:/etc/httpd/modules/mod_mpm_event.so
   #4 0x00007fd28c196cbb in startup_children () from target:/etc/httpd/modules/mod_mpm_event.so
   #5 0x00007fd28c1979af in event_run () from target:/etc/httpd/modules/mod_mpm_event.so
   #6 0x00005576b1e27c8e in ap_run_mpm ()
   #7 0x00005576b1e20383 in main ()

1. 1. 1. Expected results:
         If this change is permanent (= design change = document bug), please correct the content of the document.

or

If this change is temporal (= H2MaxWorkerIdleSeconds and H2MinWorkers will be reimplemented in the future release), please change to be functional