[ntp:questions] No libntp.so

Danny Mayer mayer at ntp.isc.org
Wed Oct 1 03:14:42 UTC 2008


Martin Burnicki wrote:
> Kay,
> 
> Kay Hayen wrote:
>> Hello NTP-World :-),
>>
>> we are implementing a NTP supervision for our ATC middleware. Initially we
>> are doing it by repeated "ntpq" executions and textual evaluations of the
>> results. We have had to notice that pipes are very unsuited for the task,
>> so we really fork it and close its stdin to make it flush. It works, but
>> it is unconvincing in performance (latency).
>>
>> It appears that the whole ntpq call is relatively slow when, when we do it
>> on e.g. RHEL 5.1 on modern Dual Core hardware, we get up to 25ms execution
>> time, which is very long for us.
> 
> As mentioned in another reply it depends on what ntpq has to do during those
> 25 milliseconds. Please be aware that this may include DNS lookups which
> might fail, so the the call would be take until the DNS lookup times out.
> 
> A proper approch would be to start a thread or task which would do the ntpq
> stuff asynchrounously and report the results to your main application when
> the reply has become available.
>  

Well any application that depends on using ntpq or any of its
functionality is broken by definition unless it's used for monitoring
purposes.

>> As we would like do other important stuff in the same process, we would
>> like to do that faster. So I had a look at the source and found that ntpq
>> is using a libntp.a that nobody seems to package though. There is no
>> libntp.so either, we had searched for those initially, but no luck.
> 

Libntp is not intended for such usage. It's intended just to provide
common functions across a number of applications in the ntp suite.

> Libntp just contains a couple of functions which are shared between several
> programs of the NTP package, e.g. ntpd, ntpq and others. It is used during
> the build process of the package in order to save compiule time.
> 

That's probably not an issue any more. It was when we had to build on
Ultrix on the flock but most modern hardware it's not really an issue.

>> Obviously we hope you will allow us to be good Free Software citizens and
>> let us drop the fork down the road. Will you?
> 
> The question is not basically whether a patch is accepted. In the first
> place the question is whether a patch makes sense at all. As already
> mentioned above I think it does not much sense just to provide libntp
> as .so file.
> 
> Martin

Whether or not we build a libntp.so or libntp.a is not as important as
it is to move more of the common functionality into the libntp library.

Danny



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