How does nginx know about FastCGI's stderr?
mdounin at mdounin.ru
Mon Mar 15 16:15:25 MSK 2010
On Mon, Mar 15, 2010 at 08:56:11PM +0800, 任晓磊 wrote:
> On Mon, Mar 15, 2010 at 5:49 PM, Maxim Dounin <mdounin at mdounin.ru> wrote:
> > http://www.fastcgi.com/devkit/doc/fcgi-spec.html
> Thank you, Maxim. The document above tells me the detail. I thought
> the protocol is a couple of stdio pipes before read this.
> So, could you tell me why I see 502 when something in FastCGI's
> stderr? Does texts from FastCGI's stderr lead to 502 ? But the specs
> says they're just application-level errors.
Writing to stderr shouldn't lead to 502 from nginx. This may
happen in two cases:
1) Application actually dies (or aborts request) after writing to
2) Bug in nginx. There is one known bug with fastcgi_cache and
large stderr from fastcgi apps which may lead to 502 returned
unexpectedly. It's mostly fixed in 0.8.34, though fix may lead to
segfaults in nginx worker when fastcgi_cache isn't used, patch is
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