Re: Help debugging hang with epoll_engine

[Henri Doreau <henri.doreau () gmail com>]

2012/6/9 Daniel Miller <bonsaiviking () gmail com>:
> Henri,
>
> It appears that the bug is epoll-specific. Earlier scans would produce
> the hang within the first 2 hostgroups or so, within 20 minutes of
> starting the scan. Now, with "--nsock-engine select" I've been running
> for over 15 hours with no hangups. Unfortunately, I'm only about 2%
> done with my scan...
>
> Dan
Hi Dan,

troubleshooting this bug is an intense (and tiring) adventure! But I
finally have some results I think. r29134 fixes a bug in nsock, where
the epoll engine could loose track of silently closed/reopened fds of
IODs. I guess this could have been the root cause of the problem you observe...
Can you try the latest revision?

Here's the associated log message:
"""
[NSOCK] Fixed an epoll-engine-specific bug. The engine didn't recognized FDs
that were internally closed and replaced by other ones. This happened during
reconnect attempts.

When reconnecting with SSL_OP_NO_SSLv2 (nsock_core.c:472), the libary closes the
fd of the current IOD, and replaces it by a new one.

The man page for epoll_ctl states that a close() on a fd makes it removed from
any epoll set it was in. Therefore, if epoll_ctl(EPOLL_CTL_MOD, ...) returns
ENOENT, we retry with EPOLL_CTL_ADD.
"""

Regards.

-- 
Henri
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