Dependency of nagios-plugins-nwc-health-8.0-1.1.src.rpm

Name: perl-Sys-SigAction

Project: openSUSE_13.2

Repository: oss

Title: Perl extension for Consistent Signal Handling

Description:
Prior to version 5.8.0 perl implemented 'unsafe' signal handling. The
reason it is consider unsafe, is that there is a risk that a signal will
arrive, and be handled while perl is changing internal data structures.
This can result in all kinds of subtle and not so subtle problems. For this
reason it has always been recommended that one do as little as possible in
a signal handler, and only variables that already exist be manipulated.

Perl 5.8.0 and later versions implements 'safe' signal handling on
platforms which support the POSIX sigaction() function. This is
accomplished by having perl note that a signal has arrived, but deferring
the execution of the signal handler until such time as it is safe to do so.
Unfortunately these changes can break some existing scripts, if they
depended on a system routine being interrupted by the signal's arrival. The
perl 5.8.0 implementation was modified further in version 5.8.2.

From the perl 5.8.2 *perlvar* man page:

The default delivery policy of signals changed in Perl 5.8.0
from immediate (also known as "unsafe") to deferred, also
known as "safe signals".

The implementation of this changed the 'sa_flags' with which the signal
handler is installed by perl, and it causes some system routines (like
connect()) to return EINTR, instead of another error when the signal
arrives. The problem comes when the code that made the system call sees the
EINTR code and decides it's going to call it again before returning. Perl
doesn't do this but some libraries do, including for instance, the Oracle
OCI library.

Thus the 'deferred signal' approach (as implemented by default in perl 5.8
and later) results in some system calls being retried prior to the signal
handler being called by perl. This breaks timeout logic for DBD-Oracle
which works with earlier versions of perl. This can be particularly vexing,
when, for instance, the host on which a database resides is not available:
'DBI->connect()' hangs for minutes before returning an error (and cannot
even be interrupted with control-C, even when the intended timeout is only
seconds). This is because SIGINT appears to be deferred as well.

Version: 0.21

Release: 2.1.3

Architecture: noarch

Size: 27.3 KB

Build Time: 2014-10-06 15:21:13 +0200 (over 9 years ago)