Apache frontend for Squeak, mod_scgi ?

Lukas Renggli renggli at student.unibe.ch
Fri Sep 26 21:51:16 UTC 2003


>> This post by Lukas Renggli also gave me pause for concern.
>> http://lists.squeakfoundation.org/pipermail/squeak-dev/2003-September/
>> 066334.html
>>
>> I hope he got that problem resolved, if so it wasn't mentioned on the
>> list to my memory.
> 
> The problem was resolved.  IIUC it didn't turn out to be a problem 
> with Squeak itself, but rather with a tricky race condition in the 
> application code.
>
> Lukas, is that correct?

The last week has been very calm, we didn't get error-messages anymore 
and the application itself run smoothly. However we had some crashes of 
the VM ...

So let me start at the very beginning: First of all, I set the VM 
parameter -notimer and at first it seemed to help a lot, but on the long 
run the problem didn't disappear.

Last weekend we could take the server in our office, as they were 
changing something at the customers site and the network would have been 
down anyway. So I had full access to that machine for the first time and 
I even managed to write some stress-tests that showed a problem. Well, 
we are not sure if this was the same problem as on the server, but it 
was a severe problem. So I rewrote the complete persistence-mechanism of 
our application and carefully protected any write-access to postgres 
with critical sections. The stress-test did run then and up-to-now we 
haven't seen our socket problem anymore.

Well, but there is still that strange feeling not knowing what the 
problem actually was. Very probably Avi is right and it was some race-
condition in our application code. Or it could have been the buggy 
SharedQueue that we are using to pool our postgres-sockets. I was 
shocked when reading Nathanael's mail about those synchronisation bugs 
in it. Why is something like this in the base-image?

To come back to the original post, we never had problems with the 
sockets of the http-connections. We are using Seaside with Comanche 5.1 
behind  Apache as https-proxy. Apache is also used to serve static 
content, like html pages, style-sheets and images. We are using this 
combination of Comanche 5.1 and Apache also in other projects and even 
on different platforms, like Linux, Windows and Mac. The speed had never 
been a problem, so we didn't felt the need to have something like mod_
scgi.

Cheers,
Lukas

-- 
Lukas Renggli
http://renggli.freezope.org



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