dovecot - Mar 2018 - "failed to map segment from shared object" in sieve pipe

Hello,

I have encountered a problem attempting to run a program in a sieve pipe. The
program is a Perl script that loads a number of binary (XS) modules at runtime.
The program crashes, it appears, if it tries to load too many. The (non-Perl
part of the) error message is "failed to map segment from shared object? ?
no additional information.

Cryptic error messages like this have the odour of imposed resource
restrictions, so I?m wondering if there are any on the pipe/filter/execute
implementation (e.g. via program_client_run).

Any configuration knobs I can twiddle? Any insights for debugging?

PS this is the dovecot 2.2.22 (fe789d2), the one that ships with Ubuntu Xenial.

Regards,

--
Dorian Taylor
Make things. Make sense.
https://doriantaylor.com

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Op 3/22/2018 om 12:14 AM schreef Dorian Taylor:
> Hello,
>
> I have encountered a problem attempting to run a program in a sieve pipe.
The program is a Perl script that loads a number of binary (XS) modules at
runtime. The program crashes, it appears, if it tries to load too many. The
(non-Perl part of the) error message is "failed to map segment from shared
object? ? no additional information.
>
> Cryptic error messages like this have the odour of imposed resource
restrictions, so I?m wondering if there are any on the pipe/filter/execute
implementation (e.g. via program_client_run).
>
> Any configuration knobs I can twiddle? Any insights for debugging?
>
> PS this is the dovecot 2.2.22 (fe789d2), the one that ships with Ubuntu
Xenial.
Those knobs depend a on your config. If there is truly some resource
limit causing this, it could be the vsz_limit of the (parent) process
invoking your program. Which service is doing that depends on your
config, either LMTP, the script service (when you're using socket
programs), or dovecot-lda (so, basically your MTA - not controlled by
Dovecot obviously).

https://wiki.dovecot.org/Services#Service_limits

Regards,

Stephan.

> On Mar 21, 2018, at 5:16 PM, Stephan Bosch <stephan at rename-it.nl>
wrote:
> 
> Those knobs depend a on your config. If there is truly some resource
> limit causing this, it could be the vsz_limit of the (parent) process
> invoking your program. Which service is doing that depends on your
> config, either LMTP, the script service (when you're using socket
> programs), or dovecot-lda (so, basically your MTA - not controlled by
> Dovecot obviously).
> 
> https://wiki.dovecot.org/Services#Service_limits
> 
> Regards,
> 
> Stephan.
Indeed it was vsz_limit. I set it to zero (under service lmtp) and now the
script works.

However I?m noticing a couple things:

1) I previously had the vsz_limit unset, and subsequently set to 256M; neither
worked.

2) I wrote a test script that just ran in a loop appending to a string and
printing to stderr how long the string was; it was killed after it reported
accumulating about 2MB.

Weird? or normal?

--
Dorian Taylor
Make things. Make sense.
https://doriantaylor.com

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