On Tuesday 01 December 2009 19:44:10 Lucas B. Cohen wrote: > On Tue, 2009-12-01 at 19:17 +0100, Kern Sibbald wrote: > > > I'm wondering how > > > safe it is in practice to attach a debugger like gdb or dbx to a > > > running process to get a stacktrace. > > > > As far as I know it is perfectly safe. I have done so *many* times, and > > after debugging detached with no harm to running programs. It is not > > something I would normally attempt on a "production" program. > > > > > Have there been incidents known to have been caused by the use of > > > btraceback/gdb/dbx during normal operations ? > > > > No, not to my knowledge, and as noted below, Bacula never calls > > btraceback/gdb/dbx during normal operations. > > That is how I understand its design from the Problem Resolution Guide > (PRG). But what I meant as a scenario was more along the lines of a > repeated, extensive usage by an operator, or as a cron job, or to comply > with a strict security policy. Or by myself, to try and get a "visual > feel" for Bacula's architecture with a debugger when I'll begin testing > and migrating to v3.0.3. > > > We do not do live debugging on Bacula. > > It's understood that the daemons don't call btraceback upon themselves > unless it's done by the exception handler. But when btraceback is called > from the command-line in order to (quote the PRG) "produce an email > showing you the current state of the daemon [...], and then exit leaving > Bacula running as if nothing happened. ", does it qualify as live > debugging ? This is what I was referring to. > > The idea is to give a fair warning to uncautious users who would be > tempted to abuse the feature after having read its manpage. Your comment > on not normally attempting this in production makes me feel it's > appropriate. > > "Interactive use of btraceback is subject to the usual risks of live > debugging, which means it can cause Bacula to crash under rare and > unfortunate circumstances."
I don't know where you came up with the above quote, but though I would not recommend using btraceback for "interactive" use, I don't believe the conclusion that is drawn is correct. It goes contrary to everything I wrote you in the last email. > > Thank you for the details. > > > Regards, > > > > Kern ------------------------------------------------------------------------------ Join us December 9, 2009 for the Red Hat Virtual Experience, a free event focused on virtualization and cloud computing. Attend in-depth sessions from your desk. Your couch. Anywhere. http://p.sf.net/sfu/redhat-sfdev2dev _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
