SO_REUSEPORT

[SplitIce]

Hi all,

I couldn't find anything in the mailing list about this issue, surely we
are not the only one?

When activating reuseport I am seeing all requests be served from a single
nginx process. All others are just idling (SIGALARM interruption of
epoll_wait / epoll_wait timeout according to strace).

Process 442 attached - interrupt to quit
epoll_wait(60, 8225010, 512, 4294967295) = -1 EINTR (Interrupted system
call)
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xe)                       = -1 EINTR (Interrupted system call)
epoll_wait(60, 8225010, 512, 4294967295) = -1 EINTR (Interrupted system
call)
--- SIGALRM (Alarm clock) @ 0 (0) ---



This only occurs with reuseport, as soon as it is disabled the load is
correctly distributed again.

Configuration:
worker_processes 12; # 2x8 cores on server
multiple server blocks on different IP's and ports with reuseaddr.
Linux kernel: 3.18.20

Server nic has interrupts over all cores:

# sudo ethtool -S eth0 |grep rx | grep pack
     rx_packets: 11244443305
     rx_queue_0_packets: 1381842455
     rx_queue_1_packets: 1373383493
     rx_queue_2_packets: 1490287703
     rx_queue_3_packets: 1440591930
     rx_queue_4_packets: 1378550073
     rx_queue_5_packets: 1373473609
     rx_queue_6_packets: 1437806438


We have also experimented with disabling iptables and anything else on the
server that could be interfering. I have also loaded it onto three other
fresh servers with the same kernel (same OS image), but with different nic
cards (with and without multiple rx queues) with no changes.

This has me stumped. Ideas?

Regards,
Mathew
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