I have a seaside application running in production, using squeak3.6 and 
the 3.6.3 VM/linux86. During the past weeks I have experienced random 
lockups, happening every few days (the app was running for months before, 
with no lockups).

symptoms
- squeak eats all cpu time
- no apparent increase in memory allocation

when I attach gdb to the process and dump stacks I see

2126057360 RWBinaryOrTextStream>next:
2126057148 HttpResponse>pvtWriteContentsOn:
2126056676 HttpResponse>writeOn:
2126056964 [] in HttpAdaptor>writeResponse:for:
2126056584 BlockContext>on:do:
2126056780 [] in HttpAdaptor>writeResponse:for:
2126056492 BlockContext>ensure:
2126056300 HttpAdaptor>writeResponse:for:
2125647964 [] in HttpAdaptor>beginConversation
2125648360 BlockContext>on:do:
2125648268 BlockContext>valueWithBindingsContext:
2125648176 BlockContext>valueWithBindings:
2125647688 BindingsAccessor>clamp:
2125647780 [] in HttpAdaptor>beginConversation
2125647544 BlockContext>ifCurtailed:
2125646204 HttpAdaptor>beginConversation
2125646112 HttpAdaptor class>readAndWriteTo:service:
2125645972 HttpAdaptor class>readAndWriteToSocket:service:
2125645760 HttpService>serve:
2125643120 [] in TcpService>value:
2125645648 BlockContext>on:do:
2125645556 BlockContext>valueWithBindingsContext:
2125645464 BlockContext>valueWithBindings:
2125645252 BindingsAccessor>clamp:
2125643304 [] in BlockContext>newProcessWithClampedBindings:
2125645160 BlockContext>on:do:
2125644976 BlockContext>valueWithBindingsContext:
2125644884 BlockContext>valueWithBindings:
2125643488 [] in BlockContext>newProcessWithBindings:
...

I've dumped the stack several times with about 10sec pause between the 
dumps, the stack is always the same.

I have tried
- compiled binary VM provided by ian
- VM compiled on the system
- rebuilding the image

I have no clue what's happening. There doesn't seem to be anything in 
RWBinaryOrTextStream>next: that could loop or deadlock. The only change 
between the old system (running fine) and this one is a minor OS upgrade 
(kernel 2.6.x to 2.6.y)

Any advice appreciated,
rado