I've never done this, but Ron's advice ($SIG{ALRM}) is in line with the
DBI perldocs.
Here is a snippet from 'perldoc DBI' - I searched for "timeout":
Signal Handling and Canceling Operations
The first thing to say is that signal handling in Perl is
currently
*not* safe. There is always a small risk of Perl crashing and/or
core
dumping when, or after, handling a signal. (The risk was reduced
with
5.004_04 but is still present.)
The two most common uses of signals in relation to the DBI are for
canceling operations when the user types Ctrl-C (interrupt), and
for
implementing a timeout using "alarm()" and $SIG{ALRM}.
To assist in implementing these operations, the DBI provides a
"cancel"
method for statement handles. The "cancel" method should abort the
current operation and is designed to be called from a signal
handler.
However, it must be stressed that: a) few drivers implement this at
the
moment (the DBI provides a default method that just returns
"undef");
and b) even if implemented, there is still a possibility that the
statement handle, and possibly the parent database handle, will not
be
usable afterwards.
If "cancel" returns true, then it has successfully invoked the
database
engine's own cancel function. If it returns false, then "cancel"
failed.
If it returns "undef", then the database engine does not have
cancel
implemented.
HTH.
Hardy Merrill
>>> "Reidy, Ron" <[EMAIL PROTECTED]> 01/20/05 12:08 PM >>>
You could set up a SIG{ALARM} and the attempt the connection.
Or better still, get your DBAs to fix the problems in the DBs.
-----------------
Ron Reidy
Lead DBA
Array BioPharma, Inc.
-----Original Message-----
From: David Goodman [mailto:[EMAIL PROTECTED]
Sent: Thursday, January 20, 2005 10:01 AM
To: dbi-users@perl.org
Subject: DBI connections to oracle sometimes hang
On occassions when an oracle instance is having
trouble, my DBI connections hang. For example, if the
oracle archive log destination is full or the OS
itself is hung, the DBI connection will also hang.
With DBI's trace level 3, it remains hung on the
following:
-> connect for DBD::Oracle::dr
(DBI::dr=HASH(0x40245c28)~0x4055c1f4 'DS1' 'su' ****
HASH(0x40553c28))
The program itself connects to a list of Oracle
servers and works fine except when the oracle instance
itself is in difficulties. This stops the processing
of the rest of the list, and does not even return an
error message.
At this site, there are a number of perl programs
performing various functions across multiple
dataservers. This issue has surfaced with Oracle but
not with Sybase.
Is there a way to have connections timeout when they
do not respond?
regareds,
David
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