Fix the empty checkpoint timeout.
The problem happens when a thread is indirectly blocked on a mutex
that another thread holds and is blocked on a weak ref access.
Add a way to do a dummy wakeup on a thread that's blocked on a mutex
so that the thread will respond to the empty checkpoint request. Do
this for the mutexes that are expected to be held when a weak ref is
accessed. Add a check that detects an unexpected case.
Bug: 33006388
Bug: 12687968
Test: test-art-host.
Change-Id: Iefec69b9a21aa25a928cb31fcf4fb872f867a8c2
diff --git a/runtime/base/mutex.h b/runtime/base/mutex.h
index ffe18c6..9b6938f 100644
--- a/runtime/base/mutex.h
+++ b/runtime/base/mutex.h
@@ -152,6 +152,16 @@
static void DumpAll(std::ostream& os);
+ bool ShouldRespondToEmptyCheckpointRequest() const {
+ return should_respond_to_empty_checkpoint_request_;
+ }
+
+ void SetShouldRespondToEmptyCheckpointRequest(bool value) {
+ should_respond_to_empty_checkpoint_request_ = value;
+ }
+
+ virtual void WakeupToRespondToEmptyCheckpoint() = 0;
+
protected:
friend class ConditionVariable;
@@ -168,6 +178,7 @@
const LockLevel level_; // Support for lock hierarchy.
const char* const name_;
+ bool should_respond_to_empty_checkpoint_request_;
// A log entry that records contention but makes no guarantee that either tid will be held live.
struct ContentionLogEntry {
@@ -266,6 +277,8 @@
// For negative capabilities in clang annotations.
const Mutex& operator!() const { return *this; }
+ void WakeupToRespondToEmptyCheckpoint() OVERRIDE;
+
private:
#if ART_USE_FUTEXES
// 0 is unheld, 1 is held.
@@ -386,6 +399,8 @@
// For negative capabilities in clang annotations.
const ReaderWriterMutex& operator!() const { return *this; }
+ void WakeupToRespondToEmptyCheckpoint() OVERRIDE;
+
private:
#if ART_USE_FUTEXES
// Out-of-inline path for handling contention for a SharedLock.
@@ -713,6 +728,12 @@
// Have an exclusive logging thread.
static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_);
+
+ // List of mutexes that we expect a thread may hold when accessing weak refs. This is used to
+ // avoid a deadlock in the empty checkpoint while weak ref access is disabled (b/34964016). If we
+ // encounter an unexpected mutex on accessing weak refs,
+ // Thread::CheckEmptyCheckpointFromWeakRefAccess will detect it.
+ static std::vector<BaseMutex*> expected_mutexes_on_weak_ref_access_;
};
class Roles {