Fix Mutex destructors being incorrectly run at exit (cl/364325997)
#345
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… which can cause crashes when `exit()` is called. See https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables for rationale and firebase/firebase-ios-sdk#6849 for a similar fix that was made in the iOS client.
Mutex destructors being incorrectly run at exit.Mutex destructors being incorrectly run at exit.
Mutex destructors being incorrectly run at exit.Mutex destructors being incorrectly run at exit (cl/364325997)
❌ Integration test FAILEDRequested by @jonsimantov on commit a4bf4d0 |
jonsimantov
previously approved these changes
Mar 29, 2021
jonsimantov
approved these changes
Mar 30, 2021
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The code base had several places where global
Mutexobjects were being allocated statically. As a result, their destructors were being run whenexit()was called. This is a violation of the Google C++ style guide, which reads:https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables
The fix is to simply create these
Mutexobjects on the heap. By doing so, the destructors will never run.Mutexobjects are not trivially destructible and the execution of their destructors at application exit has no value. Worse, it has been observed that sometimes these destructors fail, resulting in the application failing an assertion check and needlessly crashing. Admittedly, these crashes appeared to be side effects of other use-after-free bugs; however, the crashes were a red herring and hampered investigation of the true bugs.This sort of has come up before, such as the crashes fixed by firebase/firebase-ios-sdk#6849.