ART: Allow unwinding unattached threads

Partial revert of commit ed8b723c5f3989d2593ec21c65c96d6d8bf25579.

Make it (constexpr) configurable whether we allow unwinding native
stacks of unattached threads.

Bug: 27449879

Change-Id: I307a80c9a0166f33fa8a41e492d7eb0d77d0e44f

1 files changed, 5 insertions, 3 deletions

diff --git a/runtime/thread_list.cc b/runtime/thread_list.cc
index 4c81d4f1e3..afb11d33e9 100644
--- a/runtime/thread_list.cc
+++ b/runtime/thread_list.cc
@@ -57,6 +57,10 @@ static constexpr useconds_t kThreadSuspendInitialSleepUs = 0;
 static constexpr useconds_t kThreadSuspendMaxYieldUs = 3000;
 static constexpr useconds_t kThreadSuspendMaxSleepUs = 5000;
 
+// Whether we should try to dump the native stack of unattached threads. See commit ed8b723 for
+// some history.
+static constexpr bool kDumpUnattachedThreadNativeStack = true;
+
 ThreadList::ThreadList()
     : suspend_all_count_(0),
       debug_suspend_all_count_(0),
@@ -138,9 +142,7 @@ static void DumpUnattachedThread(std::ostream& os, pid_t tid) NO_THREAD_SAFETY_A
   // refactor DumpState to avoid skipping analysis.
   Thread::DumpState(os, nullptr, tid);
   DumpKernelStack(os, tid, "  kernel: ", false);
-  // TODO: Reenable this when the native code in system_server can handle it.
-  // Currently "adb shell kill -3 `pid system_server`" will cause it to exit.
-  if (false) {
+  if (kDumpUnattachedThreadNativeStack) {
     DumpNativeStack(os, tid, nullptr, "  native: ");
   }
   os << "\n";