CODEWITHSUNDEEP
androidmultithreadingandroid-binder
Matt
Matt

Reputation: 395

Does an Android process without IPC have a Binder thread-pool by default?

I know that Binder threads are used for IPC and by High-level mechanisms such as Intents. But what if an app doesn't use IPC, Intents or any form of Binder-usage, then does it still have a Binder thread-pool by default on creation of the process?

In other words: At what point in the process lifetime is the binder thread-pool instantiated? (Default at creation or before first IPC call)

Upvotes: 2

Views: 1539

Answers (1)

Technologeeks
Technologeeks

Reputation: 7897

Your binder thread pool is automatically created as part of libBinder's initialization. Specifically, apps forking from Zygote and starting the activity lifecycle call on the ActivityManager - and that's a binder call right there. The low level calls use the ProcessState object, a singleton which - upon construction - calls open_driver and shortly thereafter sets the thread pool. Technically, this is closer to first IPC call - but the point that needs emphasizing is that for App components (activities/services/receivers/providers) there are always such calls , even if you did not explicitly call context.getSystemService().

You can see this for yourself (if your device is rooted):

try ls -l /proc/$pid/fd

for any app $pid, and you will see one of the numbers (descriptors) point to /dev/binder

then do

cd /proc/$pid/task grep Name */status

and you will see the Binder_.. threads (the thread pool is named).

The only way to start a process without binder is a pure native process (i.e. NDK C project, linking with Bionic). Then, if you actually did want binder you'd either use ProcessState (and IPCThreadState), or manually code the ioctl(2) calls.

Upvotes: 3

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