How to find out the code (C++) make the game crash with signal 9(Killed)?

[seal2002]

Hello,

Preface: I'm working on a game project on the mobile platform - both on iOS/Android.

Our game is an HD+ game, which is written in C/C++ & Java.

The main code in C++ is around 90%, C from third-party libraries (curl, OpenSSL, zlib,...) less than 5%, and Java code is used for communication with the Android API.

Recently, with many changes from the team, the game randomly crashed on Android without any stack trace or bug report. Only one line:

 Zygote  : Process 21540 exited due to signal 9 (Killed).

It happens on many firmware from 9 to 13, from Samsung to Huawei(Honor), and Xiaomi...

We are trying to debug from our end (programmers) but have no luck - because it is random or did we make the debug build? However, our QA meets it in around 5% of test sessions.

I checked the following documents

https://source.android.com/docs/core/tests/debug

https://source.android.com/docs/core/tests/debug/native-crash

https://manpages.ubuntu.com/manpages/noble/en/man1/kill.1.html

Do you have any suggestions for this situation? May I miss something on the documents above?

Thanks in advance,

Hai

[yu...@unity3d.com]

Hey,

Check out if this is an LMK because of OOM. You'll see the low-memory-killer entries in the log some time before your app is killed.

To make the LMK kill the foreground process (I assume it just runs and suddenly dies?), you must be VERY aggressive on allocations. Or, search for a leak. Or, both. :) 

Yury

[enh]

yeah, even if it isn't an out-of-memory kill -- and, to be clear, i
agree with Yury that it almost certain _is_ -- we've annotated all (?)
places in the system that kill a process so that they log who's doing
the kill and why, specifically because it's so hard to debug otherwise
(because you can't catch SIGKILL, so you have no chance for a crash
dump).

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[JB Data31]

Hi,

To investigate and resolve this kind of problem, I used bugreport (/system/bin/bugreport on my android).

@JBΔ

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[enh]

(note that the original question was specifically about signal 9, aka
SIGKILL --- a signal you can't catch, so there won't be any tombstone.
like Yury said, you'll need to look in the log to see if whoever
killed you said why they killed you. but, like Yury also said, it's
because you used too much memory :-) )

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[seal2002]

Thank you, Yury and Enh
I will follow your instructions. Looks like we don't have any other choice XD.