[PATCH] D70447: [Support] ThreadPoolExecutor fixes for Windows/MinGW

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

Sorry, I lost track of this.



================
Comment at: llvm/lib/Support/Parallel.cpp:137
+      ManagedExec;
+  static std::unique_ptr<ThreadPoolExecutor> Exec(&(*ManagedExec));
+  return Exec.get();
----------------
andrewng wrote:
> ruiu wrote:
> > OK, I had to take a look at ManagedStatic's class definition to understnad that ManagedStatic is a pointer-ish class which defines operator*.
> > 
> > ManagedStatic::operator* calls RegisterManagedStatic if it is not registered yet. So I guess you don't actually have to create a unique pointer, but instead you can just do `return &*ManagedExec;`.
> As mentioned in the comment, the unique_ptr is used to actually destroy the ThreadPoolExecutor via the destructor which "stops" the ThreadPoolExecutor and also waits for the threads to complete.
> 
> The "destroy" of the ManagedStatic only "stops" the ThreadPoolExecutor and does not wait for the threads to complete.
> 
You don't truly need unique_ptr to set up an atexit call, all you need is an atexit callback that runs after the ManagedStatic is destroyed. I think the idiomatic way to do that is to make your own class with a ctor/dtor pair that saves a pointer to the ThreadPoolExecutor, and then calls the appropriate methods on it when it is destroyed. I think that will make it clearer that no memory deallocation is occuring.


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  https://reviews.llvm.org/D70447/new/

https://reviews.llvm.org/D70447