Re: spurious connection_read()s

[Howard Chu <hyc@symas.com>]

Aaron Richton wrote:
> Somewhere between 5-10 times per day (which really isn't that often for
> the load around here), slapd outputs "connection_read(%ld): no
> connection!\n", i.e. from connection.c. I ran a grep with context today,
> and found that invariably, these are immediately following a "closed" log
> message. For example:
>
>  conn=626905 fd=109 closed
>  connection_read(109): no connection!
>
>  conn=648575 fd=109 closed
>  connection_read(109): no connection!
>
>  conn=649607 fd=112 closed
>  connection_read(112): no connection!
>
>  conn=165899 fd=347 closed
>  connection_read(347): no connection!
>
>  conn=27471 fd=99 closed
>  connection_read(99): no connection!
>
>
> Why would slapd try to "connection_read" something that it apparently
> knows is "closed"?
>   

Generally this happens when a client sends an Unbind request and then 
immediately closes the connection. slapd processes the Unbind (in a 
worker thread) and begins closing the connection. At the same time, the 
listener thread gets a Readable event from select() because it detects 
that the connection has been closed by the remote end. The listener 
always calls connection_read() for Readable events, it doesn't know that 
a close is already in progress. This has nothing to do with any Solaris 
bugs or workarounds, it's just a natural occurrence, and the 
circumstance has always been there.

--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/