Symbian App life cycle: Apps never killed?
https://stackoverflow.com/questions/12767574
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05-07-2021 - |
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Coming from Android/WP7 and having been involved in Symbian projects by the past, i would like now to exactly understand the Symbian App life cycle. I want to understand how the Apps are killed.. if they are..
I found this:
"The Symbian platform is a modern preemptive multitasking operating system. Applications are created in their own process, running in a single main thread. The kernel preemptively schedules all threads in the system, based on their priority. While it is possible to create secondary threads, Symbian strongly encourages applications to co-operatively multi-task using active objects. ". Ref-link
"(..) applications may be up and running at the same time and the user may switch between active applications. When a asynchronous event occurred, running application is moved to the background but it remains active". Ref-link
It seems to me that the Apps are never killed, even when they are in background..
My question is: If the system does not kill them, how the system deals with the RAM issue? What about the possible battery drain? Does it mean that Symbian allows starting each single App, till there is not enough memory? Is there a specific meaning about the use of the Cancel/Back key that might destroy the App in certain conditions? In UIQ framework i remember a lowMemory() call-back, but one never used that..
Thanks, for your help..
Solution
Symbian Apps are indeed never killed. That allows you to have several apps running in parallel without problems. Every app should of course provide the Exit command that closes the app. Back/Hide command just leaves the app runnning and takes user back to the menu. Also every well-written app should also manage his background tasks and allow to stop them when needed.
FYI, in Symbian there might be several background tasks running that are automatically started when phone is powered on. You can get the list of them when asking for a list of processes. You can also kill any process or app if your app has enough capabilities.
