ubuntu-weather-app is polling poll() at 15Hz and heap is growing at 1K/sec on idle

[Colin Ian King]

On an idle phone, the ubuntu-weather-app is polling poll() at 15Hz. Also, I am observing heap growth at about 1K/sec.

CPU usage:
  PID Process USR% SYS% TOTAL%
  3177 qmlscene 0.24 0.48 0.72 (very light load)

System calls traced:
  PID Process Syscall Count Rate/Sec
  3177 qmlscene poll 8991 14.9849

Change in memory (K/second):
  PID Process Type Size RSS PSS
  3177 qmlscene Heap 1.71 1.20 1.20 (growing)

So it's not entirely idle and consuming power when doing apparently nothing. The heap growth is observable from the the /proc/3177/smaps information, however, I can't see any obvious sbrk()/brk() or mmap() calls, so it is curious how this is occurring.

Observation: I am noticing this with all application which are launched using qmlscene and suspect it could be qmlscene which is leaking memory. The symtoms that I see are laggy UI when leaving a qmlscene app launched for several hours while on suspend.

[Nekhelesh Ramananthan (nik90)]

I am noticing this with all application which are launched using qmlscene and suspect it could be qmlscene which is leaking memory. The symtoms that I see are laggy UI when leaving a qmlscene app launched for several hours while on suspend.

[Colin Ian King (colin-king)]

So I ran it for 30 minutes on idle, and noticed that it is leaking via mmap() calls:

Memory Change via mmap() and munmap():
  PID mmaps munmaps Change (K) Rate (K/second)
 30826 qmlscene 4 6 4096 2.28 (growing)

It grew by 4MB in 30 minutes. This is rather alarming growth. I suppose that the mmap() growth is from malloc().

As for the polling, I'm seeing two qmlscene threads running at 30 wakups a second on epoll_wait() and poll(). I've attached the complete analysis of the qmlscene to this bug report.

[Nekhelesh Ramananthan (nik90)]

I think we need to attach an upstream project for this since it is not just the weather app. I am guessing ubuntu-ui-toolkit might be one. But there could be more.

[Cris Dywan (kalikiana)]

Is this still the case?

[Colin Ian King (colin-king)]

I am pleased to report that this issue no longer affects the weather app. A common library was leaking the memory and this was fixed in the last couple of weeks. The wakeup events have dropped and so I think we can safely say this bug is now fixed.

[Launchpad Janitor (janitor)]

[Expired for ubuntu-ui-toolkit (Ubuntu) because there has been no activity for 60 days.]