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Bug 1716272

Summary: H2MinWorkers and H2MaxWorkerIdleSeconds do not work
Product: Red Hat Enterprise Linux 8 Reporter: kazuhiro kawana <kkawana>
Component: mod_http2Assignee: Luboš Uhliarik <luhliari>
Status: CLOSED MIGRATED QA Contact: rhel-cs-infra-services-qe <rhel-cs-infra-services-qe>
Severity: medium Docs Contact:
Priority: medium    
Version: 8.0CC: jorton, kwalker, luhliari, mmiura
Target Milestone: rcKeywords: MigratedToJIRA
Target Release: 8.9Flags: kwalker: mirror+
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2023-09-21 20:25:11 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
conf file none

Description kazuhiro kawana 2019-06-03 05:48:03 UTC 
### 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]
~~~

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

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


### How reproducible:

anytime


### 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


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

# 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

# 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 ()


### 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
Comment 1 kazuhiro kawana 2019-06-03 05:49:58 UTC 
Created attachment 1576485 [details]
conf file
Comment 4 RHEL Program Management 2023-09-21 20:12:14 UTC 
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.
Comment 5 RHEL Program Management 2023-09-21 20:25:11 UTC 
This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there.

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Comment 6 Red Hat Bugzilla 2024-01-20 04:25:03 UTC 
The needinfo request[s] on this closed bug have been removed as they have been unresolved for 120 days