Lighttpd

as shown by the following backtrace :

Thread 16384 (LWP 13476)
mod_proxy_core_address.c.158: (trace) resolving localhost on port 8009
mod_proxy_core_address.c.63: (trace) adding 127.0.0.1:8009 to the address-pool
Thread 32769 (LWP 13477)
Thread 16386 (LWP 13478)

Program received signal SIGSEGV, Segmentation fault.
to Thread 16384 (LWP 13476)
0x0805c75c in fdevent_get_revents (ev=0x807bea8, event_count=1,
revents=0x8082158) at fdevent.c:218
218 r->handler = ev->fdarrayr->fd->handler;
(gdb) bt
#0 0x0805c75c in fdevent_get_revents (ev=0x807bea8, event_count=1,
revents=0x8082158) at fdevent.c:218
#1 0x0804e2f1 in lighty_mainloop (srv=0x806ff08) at server.c:976
#2 0x0804f31c in main (argc=1, argv=0x1, envp=0xbfffe7d8) at server.c:1690
#3 0x4009d7f7 in __libc_start_main () from /lib/i686/libc.so.6

and the following error log

log.c.139: (trace) server started
mod_proxy_core.c.1506: (trace) connect to backend timed out
mod_proxy_core.c.1506: (trace) connect to backend timed out

the problem can be reproduced by using lighttpd with linux 2.4 and proxy_ajp13 with a configuration like :

server.event-handler = "linux-rtsig"

server.modules = (
"mod_accesslog",
"mod_proxy_core",
"mod_proxy_backend_ajp13"
)

$HTTPurl =~ "^/" {
proxy-core.balancer = "round-robin"
proxy-core.protocol = "ajp13"
proxy-core.backends = ( "localhost:8009" )
proxy-core.max-pool-size = 16
}

when the connection to the webserver from a browser client hungs (which is another problem per se) wait several seconds (the code seems to require 60 to timeout the backend) and then hit the "stop" button in the browser.

lighttpd will segfault after printing the message about the backend timeout