syslog-ng OSE v3.30.1 - slowdown when using env variable in destination clause

I have a pair of syslog-ng OSE servers on different LANs, which forward some of the log entries that they receive to separate collectors. In other words,

                Syslog-A   ->  collector-A
                Syslog-B  ->  collector-B

I would like for the two syslog servers to use a common syslog-ng.conf for obvious reasons. I first built destination clauses with the separate IPs, like so:

destination d_collector {
    udp(
        "192.168.1.23"
        port(514)
        template("${DATE} ${HOST} ${MSG}")
    );
};

This worked fine. But when I define an environment variable, COLLECTOR_IP, and then change my configuration to:

destination d_collector {
    udp(
        "`COLLECTOR_IP`"
        port(514)
        template("${DATE} ${HOST} ${MSG}")
    );
};

Then syslog-ng's throughput slows down to a trickle (but does continue); CPU utilization (ordinarily substantial - this is a busy log handler) drops to near zero. Changing the configurations back to use the raw IP address restored previous throughput. There are no unusual messages in syslog-ng's own logfile.

Anyone seen this puzzling behavior?

Thanks,
Jon Wilson
[email protected]<mailto:[email protected]>

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