Comment 19 for bug 579313

@petrj: I'm pretty sure that the interaction with your PHP service is a coincidence. I believe this is a race condition, so changing random things to arrange for more or fewer processes to be running could easily perturb the behaviour. This behaviour of X happens when the terminal X is running on is set into Canonical Mode under X's feet: https://bugs.launchpad.net/ubuntu/+source/plymouth/+bug/540256/comments/5 is a detailed description of a sequence of events from a previous occurrence of this bug, although that bug has been fixed so the details will not be quite the same here.

I've been investigating an strace given to me by Naty Bidart, who was experiencing a similar bug. I can only make some guesses at what's happening as this strace only covers what plymouthd is doing:

 * plymouth sets terminal into Raw Mode on startup
 * plymouth appears to be configured to use the details theme (i.e. no splash), which is not the same as @petrj's debug log - in fact, in @petrj's case, things work *only* if using the details theme
 * gdm calls plymouth deactivate to prepare for transition to X, which sets terminal back into Canonical Mode
 * gdm calls plymouth --has-active-vt, which says yes, so it then calls gdm_server_start_on_active_vt
 * about 0.4 seconds later, gdm calls plymouth quit --retain-splash, which cleans up and exits
 * at no point does plymouthd change the active VT, implying that http://cgit.freedesktop.org/plymouth/commit/?id=8c7b2de6913870167bee60f73423841721f1a2cc (which initially looked like a promising fix) is not relevant

Unfortunately this doesn't leave me a whole lot wiser than before, but I thought it was better to post this than not. Perhaps it will trip a switch in somebody's mind, or maybe I will come back to this later and figure it out ...