[Zope] Problems with pcgi_wrapper.exe

[Duncan Booth]

> I am running Zope as a service under WinNT workstation. I am running it
> behind "Personal Web Server". Problem is that pcgi_wrapper.exe seems to
> hang. If I access a page with a large graphic on it I might get the page but
> the graphic will not come but it will still try loading it. Anyone had a
> similar problem?
> 

There seem to be a variety of reasons for pgi_wrapper to hang on 
NT. In my case, running behind Netscape it hangs when someone 
requests an objects and then closes the connection before the 
object is sent back from pcgi_wrapper to the Netscape server. In 
this situation it appears that Netscape fails to close the pipe, but 
never reads from it.

I think there may also be a situation where the NT version can hang 
if Zope throws an exception within its handling of the pcgi request 
(pcgiReadSocket checks its result only for SOCKET_ERROR 
whereas pcgiRead checks for any error or for a 0 return). When 
Zope throws an exception it can close its socket without writing the 
data and the recv call then repeatedly returns 0. You should be 
able to tell if this is the problem because the hung pcgi_wrapper 
will be consuming all available CPU. If it hangs because the output 
pipe is closed it consumes no CPU.

What I can offer anyone who is having problems with pcgi_wrapper 
on NT is a specially patched version that shoots itself after it has 
been running for 1 hour (or any other delay if you recompile it). As 
a bonus, when it does shoot itself it writes the the pcgi logfile a 
message telling you on which line it hung. Unfortunately 
(confession time) I don't seem to have saved a copy of the source 
for the version that prints out the line number, just the binary. I do 
have source though for the version that shoots itself, but doesn't tell 
you how far it got. I have uploaded the relevant files to
http://www.zope.org/Members/Duncan/pcgimods


-- 
Duncan Booth                                             duncan@dales.rmplc.co.uk
int month(char *p){return(124864/((p[0]+p[1]-p[2]&0x1f)+1)%12)["\5\x8\3"
"\6\7\xb\1\x9\xa\2\0\4"];} // Who said my code was obscure?
http://dales.rmplc.co.uk/Duncan