Strange behavior with custom module and http proxy

Piotr Sikora piotr.sikora at
Tue Dec 22 16:42:54 MSK 2009

Hi Brian,

> I have created a (very) small module that demonstrates the problem.
> It can be downloaded here:

Few notes:
1) This problem isn't related to caching at all, simple "proxy_pass" 
also produces this behavior.
2) I believe that execv() is source of this problem, not fork().

Anyway, it seems that calling execv() with open sockets copies all file 
descriptors to new process and nginx is expecting some action to happen 
on them. Since there is no action, nginx waits until your process exits 
(and OS closes all its file descriptors for you).

I've attached simple patch, which fixes this problem.

There are few things to consider:
1) This works well with kevent (*BSD), I'm not sure what will be the 
effect of closing sockets registered with epoll (Linux), because when I 
was developing ngx_slowfs_cache, nginx crashed when listening sockets 
were closed after fork() under Linux.
2) This works as expected for single request. Under high load you might 
need to close sockets for *all* requests... But I'm not really sure 
about this and it's up to you to test this.

Best regards,
Piotr Sikora < piotr.sikora at >

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