hung apache during shutdown, was: one word syncronize once more

["Darryl L. Miles" <da...@netbauds.net>]

 From another thread "Re: one word syncronize once more", new thread 
created as I also don't believe the issues are related.

Greg Ames wrote:
 > if you have a hung server, I would do some more diagnosis and not get 
sidetracked by MRPC.  have you looked for unusual messages in the error 
log, especially messages that mention MaxClients?  have you gotten 
samples of the server-status page with ExtendedStatus on?  do you see a 
pattern with certain URLs that hang and others that do not?  are small 
local static files always served quickly?


The hung apache runtime always occur after the leader apache process has 
been given its signal to terminate.  So talking in terms of what web 
pages it serves makes no sense, since it has already shutdown all 
further webpage processing.  The fatal bug is that the apache leader 
process does not terminate in good time and remains running.  I believe 
it also hang onto the bound listerning tcp sockets as well, obvious a 
kill -9 gets rid of it.

I'm not sure without any extra information if this list will be able to 
assist in the matter, maybe there is someway to have apache emit debug 
logging information to stdout/stderr which I can capture to see where in 
apache it is hung up and what it is waiting for, maybe a sledgehammer 
approach of using a SIGALRM and new handler to be put in place as soon 
as apache begins its shutdown.  This new handler will raise a SIGKILL on 
itself should it go off.  Its unlikely I'd have chance to investigate 
this matter in the short term anyway.

I was just using the previous thread as an example to get insight into 
what actual real life problems may result from lost increment/decrements 
due to SMP concurrent issues.

Darryl

Re: hung apache during shutdown

[Rainer Jung <ra...@kippdata.de>]

Darryl L. Miles wrote:
> The hung apache runtime always occur after the leader apache process has 
> been given its signal to terminate.  So talking in terms of what web 
> pages it serves makes no sense, since it has already shutdown all 
> further webpage processing.  The fatal bug is that the apache leader 
> process does not terminate in good time and remains running.  I believe 
> it also hang onto the bound listerning tcp sockets as well, obvious a 
> kill -9 gets rid of it.

Some OSes have good tools for process inspection (or: for some OSes I 
know them):

Linux: gstack
Solaris: pstack, gcore
Most OSes: gdb

Regards,

Rainer