CMP compatible Connection Limit per pool member

I don't think that's quite right, no. You're trying to limit the number of connections (keys) that each pool member (subtable) has. So your subtable name should be the pool member, not the client. Also, there's a tiny bug with some examples from that article series, but it's easily fixed:

 

 

when CLIENT_ACCEPTED {
    set key "[IP::client_addr]:[TCP::client_port]"

when LB_SELECTED {
    set tbl "connlimit:[LB::server]"

    table set -subtable $tbl $key "ignored" 180    
    if { [table keys -subtable $tbl -count] > 5 } {
        table delete -subtable $tbl $key
        event CLIENT_CLOSED disable
        reject
    } else {
        set timer [after 60000 -periodic { table lookup -subtable $tbl $key }]
    }

when CLIENT_CLOSED {
    after cancel $timer
    table delete -subtable $tbl $key
}

I haven't tested this code, but it should work. The purpose of the timer is to keep the entry in the subtable for as long as the connection exists. Otherwise the connection could still be alive but the subtable entry could expire. If the client closes normally, the CLIENT_CLOSED event will fire which will delete the entry and cancel the timer. If there's some very unusual condition and CLIENT_CLOSED doesn't fire, the timer will get cleaned up automatically, and the subtable entry will expire on its own, exactly preventing any zombie subtable entries (which would mess up the count). Finally, if this solution doesn't work for you, you could just disable CMP on the virtuals which need this extremely low connection count.