Fix ASAN violations when shutting down FiberManager from python

Reviewed By: andriigrynenko

Differential Revision: D26497717

fbshipit-source-id: 35307fce7f9e85882f8f9e5a6bdfe651122727a3

folly/fibers/FiberManager.cpp

@@ -102,7 +102,7 @@ FiberManager::~FiberManager() {
     fibersPool_.pop_front_and_dispose([](Fiber* fiber) { delete fiber; });
   }
   assert(readyFibers_.empty());
-  assert(fibersActive_ == 0);
+  assert(!hasTasks());
 }
 
 LoopController& FiberManager::loopController() {

folly/python/fiber_manager.pxd

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 from libcpp.memory cimport unique_ptr
+from libcpp cimport bool
 from folly.executor cimport cAsyncioExecutor
 
 cdef extern from "folly/fibers/LoopController.h" namespace "folly::fibers":
@@ -24,7 +25,7 @@ cdef extern from "folly/fibers/FiberManagerInternal.h" namespace "folly::fibers"
         pass
     cdef cppclass cFiberManager "folly::fibers::FiberManager":
         cFiberManager(unique_ptr[cLoopController], const cFiberManagerOptions&)
-        void loopUntilNoReady()
+        bool hasTasks() const
 
 cdef extern from "folly/fibers/ExecutorLoopController.h" namespace "folly::fibers":
     cdef cppclass cAsyncioLoopController "folly::fibers::ExecutorLoopController"(cLoopController):

folly/python/fiber_manager.pyx

@@ -16,6 +16,10 @@ import asyncio
 from cython.operator cimport dereference as deref
 from libcpp.memory cimport unique_ptr
 from folly.executor cimport get_executor
+from libcpp.cast cimport (
+    dynamic_cast,
+)
+from folly.executor cimport cAsyncioExecutor
 from folly.fiber_manager cimport (
     cFiberManager,
     cLoopController,
@@ -29,17 +33,22 @@ loop_to_controller = WeakKeyDictionary()
 
 cdef class FiberManager:
     cdef unique_ptr[cFiberManager] cManager
+    cdef cAsyncioExecutor* cExecutor
 
     # Lazy constructor, as __cinit__ doesn't support C types
     cdef init(self, const cFiberManagerOptions& opts):
+        self.cExecutor = get_executor()
         self.cManager.reset(new cFiberManager(
             unique_ptr[cLoopController](new cAsyncioLoopController(
-                get_executor())),
+                self.cExecutor)),
             opts));
 
     def __dealloc__(FiberManager self):
+        while deref(self.cManager).hasTasks():
+            self.cExecutor.drive()
         # drive one last time
-        deref(self.cManager).loopUntilNoReady()
+        self.cExecutor.drive()
+
         # Explicitly reset here, otherwise it is possible
         # that self.cManager dstor runs after python finalizes
         # Cython deletes these after __dealloc__ returns.