Re: Perl DBI sets $SIG{PIPE} to 'IGNORE'

damian keefe wrote:
> I'm no software engineer, but given that it is known that some of the 
> libraries used by DBI 'mess with' signal dispositions in apparently 
> unknown ways,
> would it not make sense for DBI.pm to preserve the state of %SIG on 
> entry and reinstate it on disconnect/END/EXIT
>
> cheers
>
> Damian
>
>
Hang on a minute. Firstly, we have not ascertained that the MySQL (which 
I now know you are using) does fiddle with SIGPIPE. Also, the example I 
quoted was for Oracle and to the best of my knowledge the source code 
for the Oracle client libraries (OCI API) are not public. We know the 
OCI libraries mess with signals (sometimes and it depends on the 
connection method) because we've traced the code with truss/strace etc 
and can see it not because we've seen the code.

To do what you suggest would add an overhead to every DBI method call 
which ends up in a DBD.

Signals in UNIX are per process (don't even talk about threads where 
things get real messy). Personally, I don't want DBI continually 
recording a signal's disposition (BTW, which one, there are loads) and 
restoring it/them because I want all the speed I can get and signals are 
not bothering me. You found a workaround but assuming the MySQL 
libraries do change SIGPIPE you have to ask yourself why - presumably 
not because a programmer just thought it would be nice without a reason. 
Even if the client libraries you use do fiddle with signals there are 
other solutions. If you are only worried about what happens after 
disconnect and the MySQL libraries do not restore a signal after 
disconnect then I could easily argue the problem is in MySQL and not 
DBI. If you want to use backticks etc whilst connected to MySQL then 
that is a different issue.

Lets find out IF and WHY the MySQL libraries do this before solving a 
problem no one but you seems to have.

I guess I;m saying this is not as straight forward as you think.

Martin
> On 28 Jul 2010, at 19:22, Martin J. Evans wrote:
>>>
>> I suspect you'll find its your driver library that ignores SIGPIPE as 
>> AFAIK, DBI does not.
>> Oracle's OCI library changes some signal dispositions for sure and 
>> sometimes SIGPIPE/SIGCHLD.
>>
>> Martin
>>
>> <snipped example code>
>