Hi,
when I run my iOS app with thread sanitizer enabled I get tons of data race warnings when accessing an singleton:
+ (SessionContext *)sharedSessionContext {
static SessionContext *sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[SessionContext alloc] initSingleton];
});
return sharedInstance;
}I can't spot the difference of the code above to the proposed pattern from WWDC 2016 session 412 (besides the usage of a function instead of a class function):
Singleton *getSingleton() {
static dispatch_once_t predicate;
dispatch_once(&predicate, ^{
sharedInstance = [[self alloc] init];
});
return sharedInstance;
}Error log:
file:///Sources/***/Common/Context/SessionContext.m: runtime: Threading Issues: Data race in +[SessionContext sharedSessionContext] at __llvm_gcov_ctr.2583
notice: Threading Issues: '__llvm_gcov_ctr.2583' is a global variable (0x10db63af8)
Write of size 8 by thread 4
#0 0x0000000108155267 in +[SessionContext sharedSessionContext] at /Sources/***/Common/Context/SessionContext.m:157
#1 0x0000000107504b05 in __43-[LogonController loadData:]_block_invoke at /Sources/***//LogonController:288
#2 0x00000001100d589c in __tsan::invoke_and_release_block(void*) ()
#3 0x000000011aa9edb5 in _dispatch_client_callout ()
Write of size 8 by thread 15
#0 0x0000000108155267 in +[SessionContext sharedSessionContext] at Sources/***/Common/Context/SessionContext.m:157
#1 0x000000010688aa84 in -[TitleView loadLogoLoggedIn] at /Sources/***/TitleView.m:260