Am 12.11.2017 um 15:42 schrieb Guillaume Quintard <[email protected]>: > > On Sat, Nov 11, 2017 at 9:48 PM, <[email protected]> wrote: > >> I was observing a behavior of a PHP script on one backend server that got >> executed/requested >> twice (but not by the client/browser). >> >> The plain script just processes data and only outputs a response until its >> done. The observed >> behavior is; when first_byte_timeout passes but the script is still >> processing data, the varnish >> node answers with an 503 and the script gets listed twice in the webserver >> process list. So, either >> it gets requested on this event again or the TCP connection close triggers >> an new execution. In any >> case its a bug and because of missing resources to dive into a more deeper >> analyses, I just disabled >> the enabled keep-alive option of the backend webserver (apache/httpd). The >> results: it helped to avoid >> a further execution of the script. >> >> The question is: What is the best practice to configure the backend >> webservers? Do you keep the >> keep-alive option enabled or not? >>
Hi Guillaume, > > Why not just up the timeout value? Sure, the mentioned script(task) is for my taste conceptually bad designed and I could convinced the developer to run some kind of a task queue. The primary focus of my question targeted the keep-alive part but while here: does it have negative implications having e.g. a 2h first_byte_timeout configuration? Is this common? > Usually, you want to keep the keep-alive as it's much more efficient. Also sure, but my big picture while asking was - heavy traffic. While the costs of the TCP handshake persists, the scenario is at the backend of the architecture where high bandwidth links exits. So, i can imagine that in heavy traffic scenarios, the keep-alive feature would lead to more memory consumption, more file descriptors and be more prone to denial of service attacks. Any experiences out there? -- Thanks, Leon _______________________________________________ varnish-misc mailing list [email protected] https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
