net/nylon hangs in read(2) under FreeBSD10

[Pavel Timofeev]

Hello!
I used net/nylon (socks proxy server, born in openbsd) for some time
under FreeBSD10.0-RELEASE amd64.
I had no problems in testlab with that configuration.
But now I have problems in production with that.
Sometimes nylon starts to eat whole CPU.

For example, I have proxy.xxx.ru (192.168.31.198) and client1.xxx.ru
(192.168.2.6).
Here is what I see every time.
Let's say that hung nylon has pid 5323

# truss -p 5323
......
read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
temporarily unavailable'
read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
temporarily unavailable'
read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
temporarily unavailable'
read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
temporarily unavailable'
read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
temporarily unavailable'
^C

Nylon tries to read from FD 6 (right?) and gets errno 35. Infinite loop.


# lsof -p 5323
COMMAND  PID USER   FD   TYPE             DEVICE SIZE/OFF    NODE NAME
nylon   5323 root  cwd   VDIR               0,96     1024       2 /
nylon   5323 root  rtd   VDIR               0,96     1024       2 /
nylon   5323 root  txt   VREG               0,96    34840 1134069
/usr/local/bin/nylon
nylon   5323 root  txt   VREG               0,96   111696  240770
/libexec/ld-elf.so.1
nylon   5323 root  txt   VREG               0,96   306532 2970271
/usr/local/lib/event2/libevent-2.0.so.6
nylon   5323 root  txt   VREG               0,96  1567216  481549 /lib/libc.so.7
nylon   5323 root  txt   VREG               0,96   105104  481569
/lib/libthr.so.3
nylon   5323 root    0u  VCHR               0,15      0t0      15 /dev/null
nylon   5323 root    1u  VCHR               0,15      0t0      15 /dev/null
nylon   5323 root    2u  VCHR               0,15      0t0      15 /dev/null
nylon   5323 root    4u  IPv4 0xfffff800646b9c00      0t0     TCP
proxy.xxx.ru:socks (LISTEN)
nylon   5323 root    5u  unix 0xfffff8006494d000      0t0
->0xfffff800098862b8
nylon   5323 root    6u  IPv4 0xfffff8011cd07400      0t0     TCP
proxy.xxx.ru:socks->client1.xxx.ru:45737 (ESTABLISHED)

Looks like that FD is last line in this output. It's tcp socket (right?).


# sockstat | grep 5323
root     nylon      5323  4  tcp4   192.168.31.198:1080   *:*
root     nylon      5323  5  dgram  -> /var/run/logpriv
root     nylon      5323  6  tcp4   192.168.31.198:1080   192.168.2.6:45737

That pid has open socket with client1.xxx.ru (192.168.2.6).

I looked to open sockets in client1.xxx.ru and didn't find suitable.

And I can kill that hung pid only using "kill -9".


It appears to be a problem here. But where? In nylon or even in FreeBSD?
I'm not UNIX OS and programming professional and I don't know wheater
OS has to return errno 35 for read of that dead(?) socket.
Do I have to provide more info? Which one? I'm looking forward!
It happens quite often now.