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Repair thread-unsafe modifications of n_alive in F.pass.cpp 

In this example, the ctor of G runs in the main thread in the expression G(), and also in the copy ctor of G() in the DECAY_COPY inside std::thread. The main thread destroys the G() instance at the semicolon, and the started thread destroys the G() after it returns. Thus there is a race between the threads on the n_alive variable.

The fix is to join with the background thread before attempting to destroy the G in the main thread.

llvm-svn: 344820
This commit is contained in:
Billy Robert O'Neal III 2018-10-19 23:45:45 +00:00
parent 8d947bad09
commit e04704b9a9
1 changed files with 10 additions and 4 deletions
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14
libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.constr/F.pass.cpp
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@ -157,8 +157,11 @@ int main()
{
assert(G::n_alive == 0);
assert(!G::op_run);
std::thread t((G()));
t.join();
{
G g;
std::thread t(g);
t.join();
}
assert(G::n_alive == 0);
assert(G::op_run);
}
@ -185,8 +188,11 @@ int main()
{
assert(G::n_alive == 0);
assert(!G::op_run);
std::thread t(G(), 5, 5.5);
t.join();
{
G g;
std::thread t(g, 5, 5.5);
t.join();
}
assert(G::n_alive == 0);
assert(G::op_run);
}