Re: [libmicrohttpd] Sockets remain in CLOSE_WAIT state

[Christian Grothoff]

Ah, sorry, I confused CLOSE_WAIT with TIME_WAIT. Hmm. You wrote that you
set the timeout to 0, which means "disable". Maybe that is the issue?

On 1/5/19 5:34 AM, Santos Das wrote:
> Hi Christian,
> 
> We see that it never times out, i.e remain in CLOSE_WAIT state forever.
> 
> Also, it is seen irrespective of whether we use loop back ip or a
> regular eth0 IP.
> 
> From my reading, I understand the following and we don't see that FIN is
> received from Client but , we don't send FIN.
> CLOSE_WAIT means that the local end of the connection has received a FIN
> from the other end, but the OS is waiting for the program at the local
> end to actually close its connection.  
> 
> 
> 
> On Sat, Jan 5, 2019 at 4:36 AM Christian Grothoff <address@hidden
> <mailto:address@hidden>> wrote:
> 
>     Hi Santos,
> 
>     CLOSE_WAIT is a TCP state in the kernel after a TCP connection is
>     finished. It typically lasts like 60--300s, depending on your kernel
>     configuration (you may want to read up on the TCP state machine).
>     You can change the time by changing
>     /proc/sys/net/ipv4/tcp_fin_timeout, but usually this is not an issue
>     (unless you have _way_ too many TCP connections from the same host, I've
>     only seen this matter on loopback, in which case usually enabling
>     keep-alive on the client-side helps).
> 
>     Summary: this is not an issue in MHD, likely not one for anyone, just a
>     TCP artifact.
> 
>     Happy hacking!
> 
>     -Christian
> 
>     On 1/4/19 6:29 PM, Santos Das wrote:
>     > Hi Christian,
>     >
>     > Please note I am using suspend-resume and not
>     > implementing MHD_OPTION_NOTIFY_CONNECTION to close . Not sure when the
>     > library closes the connection after it receives FIN and move to
>     CLOSE_WAIT.
>     >
>     > Any pointers?
>     >
>     > thanks, santos
>     >
>     > On Fri, Jan 4, 2019 at 10:27 PM Santos Das <address@hidden
>     <mailto:address@hidden>
>     > <mailto:address@hidden <mailto:address@hidden>>> wrote:
>     >
>     >     Hi Christian,
>     >
>     >     Wishing you a happy new year!
>     >
>     >     We have set the MHD_OPTION_CONNECTION_TIMEOUT to 0 and we see that
>     >     all the connections remain in CLOSE_WAIT state. 
>     >
>     >     We also have set the MHD_OPTION_CONNECTION_LIMIT to 1000 .
>     >
>     >     Any idea what could be wrong ?
>     >
>     >     Thanks, Santos
>     >
>

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