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Posted to users@httpd.apache.org by Arnab Ganguly <ag...@gmail.com> on 2008/09/17 18:30:46 UTC
[users@httpd] Responding to ping
Hi All,
Is it possible that Apache server stops responding under heavy load, but it
responds to ping? What would be the possible causes for this?
Remote client is getting connection refused when it tries to connect.But
when the I ping the server from the client box it shows the server is alive.
Thanks
-A
Re: [users@httpd] Responding to ping
Posted by Eric Covener <co...@gmail.com>.
On Wed, Sep 17, 2008 at 12:30 PM, Arnab Ganguly <ag...@gmail.com> wrote:
> Hi All,
> Is it possible that Apache server stops responding under heavy load, but it
> responds to ping? What would be the possible causes for this?
> Remote client is getting connection refused when it tries to connect.But
> when the I ping the server from the client box it shows the server is alive.
> Thanks
> -A
>
If you hit MaxClients, apache will be able to accept some number of
new connections but not really do anything with them. Eventually it
won't be able to accept new connections (see ListenBacklog)
--
Eric Covener
covener@gmail.com
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Re: [users@httpd] Responding to ping
Posted by fchan <fc...@molsci.org>.
Dragon is correct. Apache can be overload due many issues (ie overly
popular site or DoS attack, etc.) but the system will still ping and
respond to other ports and services. Apache will hit the limit and
not respond to http request, which is good, to prevent your system
from DoS or crash.
There are some firewalls that can detect and thwart some DoS attacks
which you can research on your own for if you wish.
Frank
>Arnab Ganguly did speak thusly:
>>Hi All,
>>Is it possible that Apache server stops responding under heavy
>>load, but it responds to ping? What would be the possible causes
>>for this?
>>Remote client is getting connection refused when it tries to
>>connect.But when the I ping the server from the client box it shows
>>the server is alive.
>>Thanks
>>-A
>---------------- End original message. ---------------------
>
>Yes, a machine can indeed respond to a ping (ICMP echo request)
>while another application is not responding.
>
>Apache can get completely bogged down by a large number of requests
>but the ICMP mechanism is built into the TCP/IP stack in the OS and
>takes very little in the way of processor or time resources to
>implement. As far as I know, all modern OS platforms on which Apache
>runs are multitasking with a preemptive scheduler which means each
>application gets some share of the processor time on a periodic
>basis. So it is entirely possible that it will continue to work
>while Apache is overloaded.
>
>Dragon
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Venimus, Saltavimus, Bibimus (et naribus canium capti sumus)
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
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Re: [users@httpd] Responding to ping
Posted by Dragon <dr...@crimson-dragon.com>.
Arnab Ganguly did speak thusly:
>Hi All,
>Is it possible that Apache server stops responding under heavy load,
>but it responds to ping? What would be the possible causes for this?
>Remote client is getting connection refused when it tries to
>connect.But when the I ping the server from the client box it shows
>the server is alive.
>Thanks
>-A
---------------- End original message. ---------------------
Yes, a machine can indeed respond to a ping (ICMP echo request) while
another application is not responding.
Apache can get completely bogged down by a large number of requests
but the ICMP mechanism is built into the TCP/IP stack in the OS and
takes very little in the way of processor or time resources to
implement. As far as I know, all modern OS platforms on which Apache
runs are multitasking with a preemptive scheduler which means each
application gets some share of the processor time on a periodic
basis. So it is entirely possible that it will continue to work while
Apache is overloaded.
Dragon
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Venimus, Saltavimus, Bibimus (et naribus canium capti sumus)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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