What other mod_wsgi configuration is there besides the WSGIDaemonProcess
directive? That alone only creates a mod_wsgi daemon process group, but does
not tell mod_wsgi to use it. Thus cannot tell whether you are using embedded
mode or daemon mode. The logs are also odd in that would expect to see other
messages in there around when processes are created if using daemon mode, plus
an indication of whether a message is being generated from an Apache child
process or mod_wsgi daemon process.
So can you supply the other parts of the mod_wsgi configuration so can see if
properly using daemon mode or not. Also look for logs from mod_wsgi in any per
virtual host specific error log file and not just main Apache error log if you
separate them. Finally, if you are only intending to use mod_wsgi daemon mode,
ensure you add the directive:
WSGIRestrictEmbedded On
outside of all VirtualHost definitions so that any attempt to intitialise/use
Python in main Apache child processes is disabled.
Graham
> On 17 Oct 2022, at 8:07 am, stuart mcgraw <smcg4...@gmail.com> wrote:
>
> I am author of a Flask application running under Linux/Apache mod_wsgi that
> is experiencing intermittent, random segmentation faults.
>
> What is unusual is that the mod_wsgi process segfaults are occurring not at
> startup when mod_wsgi is loaded, or at when an incoming request accesses the
> app, but when the wsgi processes are just sitting there, quiescent.
>
> From a user's point of view, everything looks fine, the mod_wsgi processes
> and the app respond with the right results with no sign of trouble at the
> client's browser. But looking at the Apache logs shows the wsgi processes
> periodically segfaulting and getting restarted with no correlated incoming
> requests. They die sometimes after running for a few minutes, sometimes
> after a few hours. There are no incoming requests to the the wsgi app logged
> near the time of these crashes.
>
> For example:
> [Mon May 30 22:35:43.040387 2022] [wsgi:info] [pid 2575903:tid
> 139929303559104] mod_wsgi (pid=2575903): Initializing Python.
> [Mon May 30 22:35:43.099053 2022] [wsgi:info] [pid 2575903:tid
> 139929303559104] mod_wsgi (pid=2575903): Attach interpreter ''.
> [Tue May 31 01:29:06.434000 2022] [core:notice] [pid 2876203:tid
> 139929303559104] AH00052: child pid 2511562 exit signal Segmentation fault
> (11)
> [Tue May 31 01:29:07.466268 2022] [wsgi:info] [pid 2605661:tid
> 139929303559104] mod_wsgi (pid=2605661): Initializing Python.
> [Tue May 31 01:29:07.517413 2022] [wsgi:info] [pid 2605661:tid
> 139929303559104] mod_wsgi (pid=2605661): Attach interpreter ''.
> [Tue May 31 04:14:59.405491 2022] [core:notice] [pid 2876203:tid
> 139929303559104] AH00052: child pid 2575903 exit signal Segmentation fault
> (11)
>
> My wsgi app is still being tested so other than infrequent requests generated
> by me and a few other people there is very little traffic to it. However the
> web server itself is handling some continuous moderate volume of traffic to
> other apps including to C, Python and PHP CGI apps.
>
> What I know about the environment (if any other info would be useful I'll try
> and dig it up):
>
> $ cat /etc/*release
> PRETTY_NAME="Debian GNU/Linux 11 (bullseye)
>
> Apache, mod_wsgi, python were all built from source by the site's
> administrator.
>
> There are (at least) two Python's on the system:
> /usr/bin/python3 -- 3.9.2
> /usr/local/bin/python3 -- 3.10.1
>
> Apachche/mod_wsgi is was supposedly built against python-3.10. From
> the http server header:
> Apache/2.4.54 (Unix) OpenSSL/1.1.1n mod_wsgi/4.9.4 Python/3.10 PHP/7.4.23
>
> The Apache .conf file uses:
> WSGIDaemonProcess myapp processes=2 threads=10 \
> display-name=apache2-myapp locale=en_US.UTF-8 lang=en_US.UTF-8
>
> $ /usr/local/apache2/bin/httpd -V
> Server version: Apache/2.4.54 (Unix)
> Server built: Oct 13 2022 00:07:38
> Server's Module Magic Number: 20120211:124
> Server loaded: APR 1.6.5, APR-UTIL 1.6.1, PCRE 10.36 2020-12-04
> Compiled using: APR 1.6.5, APR-UTIL 1.6.1, PCRE 10.36 2020-12-04
> Architecture: 64-bit
> Server MPM: event
> threaded: yes (fixed thread count)
> forked: yes (variable process count)
> Server compiled with....
> -D APR_HAS_SENDFILE
> -D APR_HAS_MMAP
> -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
> -D APR_USE_SYSVSEM_SERIALIZE
> -D APR_USE_PTHREAD_SERIALIZE
> -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
> -D APR_HAS_OTHER_CHILD
> -D AP_HAVE_RELIABLE_PIPED_LOGS
> -D DYNAMIC_MODULE_LIMIT=256
> -D HTTPD_ROOT="/usr/local/apache2"
> -D SUEXEC_BIN="/usr/local/apache2/bin/suexec"
> -D DEFAULT_PIDLOG="logs/httpd.pid"
> -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
> -D DEFAULT_ERRORLOG="logs/error_log"
> -D AP_TYPES_CONFIG_FILE="conf/mime.types"
> -D SERVER_CONFIG_FILE="conf/httpd.conf"
>
> $ bin/httpd -M
> Loaded Modules:
> core_module (static)
> so_module (static)
> http_module (static)
> mpm_event_module (static)
> authz_core_module (shared)
> authz_host_module (shared)
> unixd_module (shared)
> dir_module (shared)
> access_compat_module (shared)
> env_module (shared)
> alias_module (shared)
> log_config_module (shared)
> ssl_module (shared)
> mime_module (shared)
> socache_shmcb_module (shared)
> setenvif_module (shared)
> cgid_module (shared)
> userdir_module (shared)
> headers_module (shared)
> rewrite_module (shared)
> autoindex_module (shared)
> negotiation_module (shared)
> dav_module (shared)
> deflate_module (shared)
> info_module (shared)
> status_module (shared)
> wsgi_module (shared)
> evasive24_module (shared)
> php7_module (shared)
>
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