Revert^17 "Thread suspension cleanup and deadlock fix"

This reverts commit c6371b52df0da31acc174a3526274417b7aac0a7.

Reason for revert: This seems to have two remaining issues:

1. The second DCHECK in WaitForFlipFunction is not completely guaranteed to hold, resulting in failures for 658-fp-read-barrier.
2. WaitForSuspendBarrier seems to time out occasionally, possibly spuriously so. We fail when the futex times out once. That's probably incompatible with the app freezer. We should retry a few times.

Change-Id: Ibd8909b31083fc29e6d4f1fcde003d08eb16fc0a

1 files changed, 9 insertions, 17 deletions

diff --git a/openjdkjvmti/ti_threadgroup.cc b/openjdkjvmti/ti_threadgroup.cc
index bfe6b51791..120024e8b2 100644
--- a/openjdkjvmti/ti_threadgroup.cc
+++ b/openjdkjvmti/ti_threadgroup.cc
@@ -171,26 +171,18 @@ static void GetThreads(art::Handle<art::mirror::Object> thread_group,
   CHECK(thread_group != nullptr);
 
   art::MutexLock mu(art::Thread::Current(), *art::Locks::thread_list_lock_);
-  std::list<art::Thread*> thread_list = art::Runtime::Current()->GetThreadList()->GetList();
-  // We have to be careful with threads exiting while we build this list.
-  std::vector<art::ThreadExitFlag> tefs(thread_list.size());
-  auto i = tefs.begin();
-  for (art::Thread* thd : thread_list) {
-    thd->NotifyOnThreadExit(&*i++);
-  }
-  DCHECK(i == tefs.end());
-
-  i = tefs.begin();
-  for (art::Thread* t : thread_list) {
-    art::ThreadExitFlag* tef = &*i++;
-    art::ObjPtr<art::mirror::Object> peer = t->LockedGetPeerFromOtherThread(tef);
-    if (peer != nullptr && !tef->HasExited() && !t->IsStillStarting() &&
-        IsInDesiredThreadGroup(thread_group, peer)) {
+  for (art::Thread* t : art::Runtime::Current()->GetThreadList()->GetList()) {
+    if (t->IsStillStarting()) {
+      continue;
+    }
+    art::ObjPtr<art::mirror::Object> peer = t->GetPeerFromOtherThread();
+    if (peer == nullptr) {
+      continue;
+    }
+    if (IsInDesiredThreadGroup(thread_group, peer)) {
       thread_peers->push_back(peer);
     }
-    t->UnregisterThreadExitFlag(tef);
   }
-  DCHECK(i == tefs.end());
 }
 
 static void GetChildThreadGroups(art::Handle<art::mirror::Object> thread_group,