[erlang-questions] standard_error not handling eagain?

[UENISHI Kota]

Steve,
Your patch also fixed my case. standard_error is no more exiting. It
is awesome and thank you!

Jose,
Thank you for bringing it up, I should have read letters from
erlang-questions more carefully :)

On Mon, Aug 10, 2015 at 12:56 AM, Steve Vinoski <vinoski@REDACTED> wrote:
> The patch below seems to fix it, so please give it a try if you're
> interested. Feedback welcomed. It requires more testing, as well as adding
> Kota's test to the suite to prevent regressions. I'll do that later and send
> in a PR.
>
> --steve
>
>
> diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
> index b036b20..adb449e 100644
> --- a/erts/emulator/sys/unix/sys.c
> +++ b/erts/emulator/sys/unix/sys.c
> @@ -2527,7 +2527,7 @@ fd_async(void *async_data)
>      SysIOVec      *iov0;
>      SysIOVec      *iov;
>      int            iovlen;
> -    int            err;
> +    int            err = 0;
>      /* much of this code is stolen from efile_drv:invoke_writev */
>      driver_pdl_lock(dd->blocking->pdl);
>      iov0 = driver_peekq(dd->port_num, &iovlen);
> @@ -2542,8 +2542,11 @@ fd_async(void *async_data)
>          memcpy(iov,iov0,iovlen*sizeof(SysIOVec));
>          driver_pdl_unlock(dd->blocking->pdl);
>
> -        res = writev(dd->ofd, iov, iovlen);
> -        err = errno;
> +        do {
> +            res = writev(dd->ofd, iov, iovlen);
> +        } while (res < 0 && errno == EINTR);
> +        if (res < 0)
> +            err = errno;
>
>          erts_free(ERTS_ALC_T_SYS_WRITE_BUF, iov);
>      }
> @@ -2582,7 +2585,12 @@ void fd_ready_async(ErlDrvData drv_data,
>              return /* 0; */;
>          }
>      } else if (dd->blocking->res < 0) {
> -        driver_failure_posix(port_num, dd->blocking->err);
> +        if (dd->blocking->err == EAGAIN) {
> +            set_busy_port(port_num, 1);
> +            /* still data left to write in queue */
> +            driver_async(port_num, &dd->blocking->pkey, fd_async, dd,
> NULL);
> +        } else
> +            driver_failure_posix(port_num, dd->blocking->err);
>          return; /* -1; */
>      }
>      return; /* 0; */
>
>
>
>
> On Sun, Aug 9, 2015 at 11:03 AM, José Valim
> <jose.valim@REDACTED> wrote:
>>
>> Thanks for a report that includes a way to reproduce the issue!
>>
>> For reference, this has been reported a couple days ago as well:
>> http://erlang.org/pipermail/erlang-questions/2015-August/085375.html
>>
>>
>>
>> José Valim
>> www.plataformatec.com.br
>> Skype: jv.ptec
>> Founder and Director of R&D
>>
>> On Sun, Aug 9, 2015 at 2:53 PM, UENISHI Kota <kuenishi@REDACTED> wrote:
>>>
>>> Hi folks,
>>> I'm asking here as I'm not sure how it should be although this looks
>>> like a bug to me.  Reproduced in MacOS (mine is 10.10.4) AND 18.0
>>> (maint-18 HEAD), but couldn't reproduce in Linux (Ubuntu 14.04) with
>>> 18.0 or R16B02 with Mac.
>>>
>>> To reproduce, it's pretty easy: just print out to standard_error by
>>> using io:put_char/1 or io:format/3, with writing a long iolist at
>>> least more than a thousand characters [1]:
>>>
>>> main(_) ->
>>>     Arg0 = [ [["1234567890" || _ <- [1,2,3,4,5,6,7,8,9,0]], 32,
>>> integer_to_list(L), $\n]
>>>              || L <- lists:seq(1, 200) ],
>>>     io:format(standard_error, "~p~n", [whereis(standard_error)]),
>>>     R = io:put_chars(standard_error, Arg0),
>>>     io:format(standard_error, "~p, ~p~n", [R, whereis(standard_error)]).
>>>
>>> My result of this code is also copied in that gist [2].
>>>
>>> This phenomena seems to happen when writing a long buffer to FD 2 via
>>> port driver  and suddenly gets EAGAIN back, and the port exits with
>>> that error. I believe standard_error should not exit but should retry
>>> writing when eagain or eintr was received. Thoughts?
>>>
>>> [1] https://gist.github.com/kuenishi/76333a8a93bc8ccad308#file-stderr-erl
>>> [2]
>>> https://gist.github.com/kuenishi/76333a8a93bc8ccad308#file-otp-18-0-maint-18-head
>>>
>>> --
>>> UENISHI Kota :-)
>>> _______________________________________________
>>> erlang-questions mailing list
>>> erlang-questions@REDACTED
>>> http://erlang.org/mailman/listinfo/erlang-questions
>>
>>
>>
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>



-- 
UENISHI Kota :-)