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Re: Different perl behavior between V5.10 and V5.14

by vsespb (Hermit)
on Apr 01, 2013 at 14:12 UTC ( #1026491=note: print w/ replies, xml ) Need Help??


in reply to Different perl behavior between V5.10 and V5.14

Well, obviously readline() is not retried when signal arrives (EINTR is set)

I think this should not happen: perlipc safe signals

Consequently, restartable system calls can fail (with $! set to EINTR ) in places where they previously would have succeeded. The default :perlio layer retries read, write and close as described above; interrupted wait and waitpid calls will always be retried.

Also, this perl5140delta might explain difference between 5.10 vs 5.14

"Safe signals" optimisation Signal dispatch has been moved from the runloop into control ops. This should give a few percent speed increase, and eliminates nearly all the speed penalty caused by the introduction of "safe signals" in 5.8.0. Signals should still be dispatched within the same statement as they were previously. If this does not happen, or if you find it possible to create uninterruptible loops, this is a bug, and reports are encouraged of how to recreate such issues.


Comment on Re: Different perl behavior between V5.10 and V5.14
Re^2: Different perl behavior between V5.10 and V5.14
by markseger (Beadle) on Apr 01, 2013 at 15:00 UTC
    Thanks for the details but I guess I'm not sure I really sure what to do about this, especially since an earlier reply stated this does not happen on fedora and so feels like it could be outside of perl or at least not completely inside of perl.

    From your reference to perl5140delta are you suggesting this IS a perl bug and should be reported?

    -mark

      I am not 100% sure. I would wait couple of days, until maybe some Perl maintainers confirm here that it's a bug or not.
        I've been asking around in a couple of places and someone else had pointed out that logtail itself has changed to now use inotify to tell when a file has changed and that there may now be more signals being tossed about as well. I don't know if this offers any additional info or not, but thought it worth mentioning.

        So far I've been running my modified code and it seems to be working but I'd prefer a better approach than the one I'm using so maybe someone will come up with a better way to handle this.

        thanks for all your feedback

        -mark

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