Adjust JIT thread priority post-fork.

Bug: 166406877
Test: test.py
Change-Id: I81c9a231213e62a1aeaa67cfe8c38419f5bddcd0
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 7b907cc..95c40b4 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -685,8 +685,14 @@
 }
 
 void Runtime::PostZygoteFork() {
-  if (GetJit() != nullptr) {
-    GetJit()->PostZygoteFork();
+  jit::Jit* jit = GetJit();
+  if (jit != nullptr) {
+    jit->PostZygoteFork();
+    // Ensure that the threads in the JIT pool have been created with the right
+    // priority.
+    if (kIsDebugBuild && jit->GetThreadPool() != nullptr) {
+      jit->GetThreadPool()->CheckPthreadPriority(jit->GetThreadPoolPthreadPriority());
+    }
   }
   // Reset all stats.
   ResetStats(0xFFFFFFFF);