FYI Ralph has created a bug report for this https://bugs.launchpad.net/epics-base/+bug/1527636
Can we move the conversation there?
On 12/18/2015 06:44 AM, Benjamin Franksen wrote:
> I can see three ways to move forward from here:
>
> (1) Remove the call to ca_context_destroy from the CA utilities. I don't
> like this very much: their source code should serve as demonstration of
> good practice when programming a CA client and thus should include
> proper cleanup of the client context.
Agreed, this is the least attractive.
> (2) Apply more forceful OS-specific ways of getting rid of the name
> resolution thread (even when it is blocked on a call to gethostbyaddr).
> Doing this properly would mean to adding some sort of "thread killing"
> method to the epicsThread class, something which has been proposed
> before and rejected for various good reasons.
I see this as the most appropriate solution. IMO the root problem is the lack of a portable API for async. name lookups. In the case of Linux/posix this should be fixable by sending SIGINT to the resolver thread.
I'll do a little test to see if this works.
> (3) Let the user choose whether they want to have the extra features
> enabled by the host name lookup, or whether they rather want to ensure
> quick termination of their programs or threads. This could be made
> configurable by an environment variable, for instance.
This feels like a workaround that could also be achieved through /etc/hosts.
> I think the third solution is preferable since it is backward compatible
> (no API or ABI change) and can be applied without changing the source
> code or even re-compiling (if dynamically linked) of the client
> applications.
I think that #2 can also be done in a compatible and safe way, and without adding yet another configuration option.
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