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My favorite signal surprise was running nginx and/or httpd in the foreground and wondering why on earth it quit whenver i resized the window. Turns out, they u

• eadmund 2y ago
  > Turns out, they use SIGWINCH (which is sent on WINdow CHange) for graceful shutdown. That’s … that’s even worse than people who send errors with an HTTP 200 response code.
  • chrsig 2y ago
    y'know...what really is an error, anyway?
    • thebruce87m 2y ago
      For what is an error, if not a success at failing?
      • chrsig 2y ago
        Exactly. Gotta be happy you got a response at all!
    • AStonesThrow 2y ago
      In my day, successful commands output nothing at all, so it would seem that a blank page is the only truly error-free result.
  • aunderscored 2y ago
    Disagree. Annoyingly there is a reasonable case for 200 but with an error, if http is your transport but not your application, then 200 says "yes, the message was transfered and understood correctly, here is your response" which may be an error response from the application
    • Izkata 2y ago
      For example: Apache (httpd) replaces the 4xx and 5xx response body with its own content instead of whatever you'd returned from an external handler like wsgi. You have to use a 2xx (except for 204) to get a relevant error message back out.
      • AdieuToLogic 2y ago
        > For example: Apache (httpd) replaces the 4xx and 5xx response body with its own content instead of whatever you'd returned from an external handler like wsgi. This is the default behavior. Apache httpd can be configured to produce different responses by way of ErrorDocument[0]. From the documentation: Customized error responses can be defined for any HTTP status code designated as an error condition - that is, any 4xx or 5xx status. HTH 0 - https://httpd.apache.org/docs/trunk/custom-error.html https://httpd.apache.org/docs/trunk/custom-error.html
        • jjnoakes 2y ago
          Even with custom error documents configured in the web server, you still lose the application-specific (and probably request- and error-specific) message generated by the application itself.
          • Izkata 2y ago
            Yeah, this is how we ran across it - whoever originally wrote a particular feature was trying to do the right thing by using an HTTP error code, but with a message that would be presented to the user about why that operation failed. A generic response wouldn't work, there were multiple possible reasons all fixable by the user, and tying a whole error code to one specific feature would've probably been a bad idea anyway.
    • Groxx 2y ago
      Which is why "you resized the terminal window, clearly you meant to shut down this web server" is even crazier, yes
  • thezilch 2y ago
    That's ... not what most people are doing. People send _application_ errors on HTTP 200 response codes, because HTTP response codes are for HTTP and not applications. Most "REST" libraries and webdev get this wrong, building ever more fragile web services.
    • ChocolateGod 2y ago
      Applications using status codes is useful because it can tell browsers and load balancers to not cache the page in a uniform way.
    • LoganDark 2y ago
      Task failed successfully
    • sunshowers 2y ago
      I don't think the distinction is as clear-cut as you're making it out to be. For example, HTTP 409 Conflict generally means an application-level conflict (e.g. an optimistic concurrency mechanism detected a conflict). HTTP 422 Unprocessable Entity is also usually an application-level error (e.g. hash validation failure, or identifier not recognized by the server).
• thayne 2y ago
  Why? That's what SIGTERM is for.
  • chrsig 2y ago
    No clue what the decision making process was. There's a bug report for httpd dating back to 2011[0]. The nginx mailling list also has a grumpy person contemporary with that[1]. My guess is someone thought "httpd is a server running somewhere without a monitor attached, why on earth would it get a SIGWINCH!? surely it's available to use for something completely different", not considering users running it in the foreground during development. Nginx probably followed suit for convention, but that's pure speculation on my part. Also that was before docker really took off (I'm not sure if it was around in 2011 yet; still in it's infancy maybe). Running it in the foreground didn't happen as much yet. People were still using wamp or installing it via apt and restarting via sudo. [0] https://bz.apache.org/bugzilla/show_bug.cgi?id=50669 https://bz.apache.org/bugzilla/show_bug.cgi?id=50669 [1] https://mailman.nginx.org/pipermail/nginx/2011-August/028640.html https://mailman.nginx.org/pipermail/nginx/2011-August/028640...
    • hulitu 2y ago
      > why on earth would it get a SIGWINCH!? Reminds me of those "/* not reached */" stories.
  • ibash 2y ago
    I tried to find out why. Unfortunately the change that introduces it predates the official release by a few months. And predates the mailing list by about a year: https://trac.nginx.org/nginx/changeset/5238e93961a189c13eefff01f8eccfe863159c72/nginx https://trac.nginx.org/nginx/changeset/5238e93961a189c13eeff...
    • chrsig 2y ago
      ok, I found a commit in 2005, coming about because linuxthreads was interfering with the SIGUSR1 signal. It looks like they wound up making it platform specific, so BSDs and unix like operating systems might still use SIGUSR1. https://github.com/apache/httpd/commit/395896ae8d19bbea10f82b1d40e16f4721d316b7 https://github.com/apache/httpd/commit/395896ae8d19bbea10f82...
• ykonstant 2y ago
  I don't know whether to laugh or cry.
  • chrsig 2y ago
    definitely laugh! life's too short, you'll never get out alive :)
• deleted 2y ago
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