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From Bostjan Skufca <bost...@a2o.si>
Subject Re: [users@httpd] Incomplete file downloads if Apache HTTPD is killed
Date Wed, 20 Apr 2011 18:19:48 GMT
>
> if a server is killed (SIGKILL) during a "large" static file transfer, then
>> the client is not notified by his browser that file has not been completely
>> downloaded. On Win it just says it is not a valid Win32 application or
>> corrupted or sth.
>> Now I know this is not a general problem and a graceful restart is the way
>> to go around this, but if I do an upgrade then proper restart is required,
>> or at least I think I remember I had problems with graceful restart in such
>> situations.
>>
>
> Sending a SIGKILL is an unfriendly way to end a process -- it causes the
> kernel to immediately terminate the process, without giving the process any
> chance to clean up.  SIGKILL is thus not one of the signals handled
> specially by Apache HTTP Server.  For a list of the signals that are handled
> specially, see http://httpd.apache.org/docs/2.2/stopping.html
>

Sending SIGKILL was just a way to simulate apachectl stop, which sends
SIGTERM and then if after 10s some children still did not exit, parent sends
SIGKILL to them.


> If you'd like to completely stop Apache HTTP Server so you can manually
> restart it later, then sending SIGWINCH will cause httpd to exit gracefully
> after completing any current requests or after GracefulShutdownTimeout is
> reached, whichever comes first.  Alternatively, you can cause httpd to exit
> more quickly, interrupting any current requests, by sending it a SIGTERM.  I
> don't know for sure if either of these will cause a TCP RST to be sent to
> the client, but I think the odds are better than if you used a SIGKILL.
>

Thanks for the hint, SIGWINCH (or apachectl graceful-stop) does the trick. I
still have to test it (namely if HTTPD with PHP and eAccelerator has any
troubles being restarted that way) but this looks promising. Again, RTFM
would be my friend - again:)

Thanks again,
b.

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