I am experimenting with running WSGI apps, and my server is Apache. There seems to be a lot of debate how to run Flask apps properly:<\/p>\n Since I already have Apache, using To the best of my understanding, the following rules apply.<\/p>\n You define your application(s) using You define one or more pools of WSGI “daemons” using You tell Apache which application runs in which daemon pool via You then tell Apache which Python sub-interpreter you want to use for your processing. When you are running inside a dedicated process, In general, Summary WSGIApplicationGroup is a name of the Python sub-interpreter. You don’t need sub-interpreters if you run mod_wsgi in daemon mode (i.e. with dedicated processes). Always set WSGIApplicationGroup to %{GLOBAL}. If […]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"Layout":"","footnotes":""},"categories":[4,15],"tags":[],"class_list":["entry","author-ikriv","post-5235","post","type-post","status-publish","format-standard","category-hack","category-webdev"],"_links":{"self":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5235","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5235"}],"version-history":[{"count":3,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5235\/revisions"}],"predecessor-version":[{"id":5238,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5235\/revisions\/5238"}],"wp:attachment":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5235"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5235"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5235"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}WSGIApplicationGroup<\/code> is a name of the Python sub-interpreter. You don’t need sub-interpreters if you run mod_wsgi in daemon mode (i.e. with dedicated processes). Always set WSGIApplicationGroup<\/code> to %{GLOBAL}<\/code>. If you have multiple applications, use <Location> tag in your site configuration, as follows:<\/p>\n\r\nWSGIDaemonProcess app_one processes=2 threads=15 display-name=%{GROUP}\r\nWSGIScriptAlias \/api\/wsgi\/one \/var\/www\/mysite\/api\/one\/wsgi.py\r\n\r\n<Location \/api\/wsgi\/one>\r\n WSGIProcessGroup app_one\r\n WSGIApplicationGroup %{GLOBAL}\r\n<\/Location>\r\n\r\nWSGIDaemonProcess app_two processes=2 threads=15 display-name=%{GROUP}\r\nWSGIScriptAlias \/api\/wsgi\/two \/var\/www\/mysite\/api\/two\/wsgi.py\r\n\r\n<Location \/api\/wsgi\/two>\r\n WSGIProcessGroup app_two\r\n WSGIApplicationGroup %{GLOBAL}\r\n<\/Location>\r\n<\/pre>\nMore details<\/h1>\n
\n
mod_wsgi<\/code> seems like a natural choice, but there are some caveats, especially if you run multiple applications.<\/p>\nWSGIScriptAlias<\/code> directive in the site config file. This is relatively straightforward.<\/p>\nWSGIDaemonProcess<\/code> directive.<\/p>\nWSGIProcessGroup<\/code> directive. You must use the
\n<Location> tag to differentiate between different applications, as shown in the example above.<\/p>\n
\nthere is no point using a sub-interpreter, so the specification is WSGIApplicationGroup %{GLOBAL}<\/code>. In particular, numpy doesn’t
\nlike sub-interpreters and prints a warning like this:<\/p>\n\r\nUserWarning: NumPy was imported from a Python sub-interpreter but NumPy does not properly support sub-interpreters.\r\nThis will likely work for most users but might cause hard to track down issues or subtle bugs.\r\nA common user of the rare sub-interpreter feature is wsgi which also allows single-interpreter mode.\r\nImprovements in the case of bugs are welcome, but is not on the NumPy roadmap, \r\nand full support may require significant effort to achieve.\r\n<\/pre>\n
mod_wsgi<\/code> works well, but its defaults are targeted towards the old use case, when the requests
\nwere handled in the main Apache process, and each application used its own Python sub-interpreter. You must explicitly
\nspecify the process pool and the “global” sub-interpreter for each application. This makes the configuration somewhat
\nverbose, but once you know what you’re doing it is not a big deal.<\/p>\n","protected":false},"excerpt":{"rendered":"