hazptr: Increase the thread cache capacity to 9 hazard pointers

Summary: To accommodate a use case.

Reviewed By: itomatik

Differential Revision: D8656154

fbshipit-source-id: 9d2961d7921bdd399fc8c46820d1ba3aa5006c6f

folly/synchronization/HazptrThrLocal.h

@@ -70,7 +70,7 @@ class hazptr_tc_entry {
  */
 template <template <typename> class Atom>
 class hazptr_tc {
-  static constexpr uint8_t kCapacity = 6;
+  static constexpr uint8_t kCapacity = 9;
 
   hazptr_tc_entry<Atom> entry_[kCapacity];
   uint8_t count_{0};