Relayd -- Downloading large files fails with "Cannot allocate memory"

[Andrew Klettke]

Running 4.9, downloading large files (>250MB) from a website behind a 
firewall clustered with relayd fails with the following error in our logs:

Dec  6 12:14:15 fw01 relayd[5615]: relay httpproxy, session 768464 (23 
active), 0, ********* -> 192.168.15.101:80, Cannot allocate memory


Here are the applicable relayd.conf directives:


relay httpproxy {
    listen on $relayd_addr port $relayd_port
    protocol "httpfilter"
    forward to <web_parents> port 80 mode loadbalance check http "/" 
code 200
}

http protocol "httpfilter" {
    tcp { nodelay, sack, socket buffer 65536, backlog 50 }
    return error

    header append "$REMOTE_ADDR" to "X-Forwarded-For"
    header change "Keep-Alive" to "$TIMEOUT"

}

Any thoughts? Has anyone seen anything like this before? vmstat shows 
plenty of free RAM.

--
Thanks,

Andrew Klettke
Systems Admin
Optic Fusion
253-830-2943