Logging load balancer decisions

I'd add some logging and the LB_SELECTED event to your iRule:

when HTTP_REQUEST { 
    if { [string tolower [HTTP::path]] starts_with "/abcd" } {
        log local0. "in special URI"
        set jsess [URI::query [HTTP::uri] PARAM]
        if { $jsess != "" } { 
            log local0. "jsess = $jsess"
            persist uie $jsess 180 
        } 
        log local0. "sending to default.pool1"
        pool default.pool1 
    } else { 
        log local0. "else"
        persist none
        log local0. "sending to default.pool2"
        pool default.pool2 
    } 
}
when LB_SELECTED {
    log local0. "selected: [LB::server addr]"
}

With that in place, tail the LTM log from the management shell and test:

tail -f /var/log/ltm

I'm not 100% sure what you're going for, but the above iRule will only persist if the user requests the special URI and includes the jsession query string parameter.