2.1.115 + devfs-v51 locking under high network load

Eric (erbrun@bellatlantic.net)
Thu, 13 Aug 1998 14:53:06 -0400 (EDT)


Hi,
Not sure if everyone already knows this is a bug in 2.1.115, but I have
just experienced an interesting event where, when my httpd (or any network
daemon) goes under heavy load, the system freezes until the load is expunged.
Take for example, that I just posted a picture in a webchat to about 35
people. The picture was located on my system.
After processing about 10 requests or so, my system soft locked. SysRQ still
worked, but all processes were frozen. The apparant problem was the HD more
or less--the HD just sorta locked. Presumably a disk lockup from swapping?

I also wrote a program [out of crafty need] to flood-post inside similar
chats. I tried it using my own webserver--the HTTP request nevertheless
probably didn't mean anything, but when I started the program, first of all,
nothing was happening--only about two httpd processes fork()'ed, and it was
pretty much frozen--hitting CTRL-C or CTRL-\ killed the flood program, and
also seemed to flush all the previous requests the flood program had
submitted--thus giving me a nice thrash.
It stabilized after a while, after all requests had been answered.
I tried the same thing with port 25 (sendmail, nevertheless an HTTP request
meant *nothing* to sendmail), with similar results--not much happened, no
sendmail's were fork()'ed, the spammer process was sitting there. I hit
CTRL-C on the spammer program, and sendmail must have fork()'ed at least 20
times to fulfill the requests--but during the time of the freezup when
sendmail wasn't doing anything nor vspam, I couldn't type anything at the
command line of any of my consoles. Presumably disk access freezup?

Thanks
-Eric

P.S. I am not subscribed to the list--please Cc: or To: any replies straight
to this address.

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