Databases
StackOverflow2013
Postsdbo
POStrangeness with SIGUSR2 and sleep (Qt 4 embedded)
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POStrangeness with SIGUSR2 and sleep (Qt 4 embedded)
    primarykey
    data
    text
    <p>A very odd one: I have a Qt 4 embedded app that runs on framebuffer, it normally runs from inittab as the only UI on the box. There is an option to put the machine to sleep - I do the normal thing and open /sys/power/state, write "mem" and close it (using QFile). Very straight forward and it works fine EXCEPT the first time the app runs after booting. If it sleeps then it receives SIGUSR2 and just hangs forever with a blank screen. The hang occurs after resume.</p> <p>But, if I manually kill it and run it again .. sleep works fine again. Note that it must do the failed sleep attempt and be killed - whereafter all is peachy every time it runs, SIGUSR2 never shows up again.</p> <p>I have already tried to trap the signal - doesn't trap. No idea why - except that I know that pthreads uses SIGUSR2 ..</p> <p>Stumped. Ideas? Clues?</p> <p>[edit] I found that if I fork() and write to /sys/power/state in the child and exit it sort of solves the problem, but it doesn't solve the mystery..</p> <p>[edit 2] I subsequently found that in fact the child is still hanging when the machine is shut down (causing it to hang forever without shutting down..), although the ugly hack just mentioned did fix the hang coming out of suspend - I have not figured out what is happening but finally solved it by just using a script/daemon: in a while loop it checks a file in /tmp for an action and either halts or suspends and restarts the app afterwards .. not pretty but it works.</p> <p>And still the mystery of the SIGUSR2 hang remains ..</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USaperson
    1. USaperson
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. POStrangeness with SIGUSR2 and sleep (Qt 4 embedded)
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POStrangeness with SIGUSR2 and sleep (Qt 4 embedded)
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload