| /* |
| * Copyright (C) 2011 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "thread_list.h" |
| |
| #include <dirent.h> |
| #include <sys/types.h> |
| #include <unistd.h> |
| |
| #include "debugger.h" |
| #include "mutex.h" |
| #include "timing_logger.h" |
| #include "utils.h" |
| |
| namespace art { |
| |
| ThreadList::ThreadList() |
| : allocated_ids_lock_("allocated thread ids lock"), |
| suspend_all_count_(0), debug_suspend_all_count_(0), |
| thread_exit_cond_("thread exit condition variable", *Locks::thread_list_lock_) { |
| } |
| |
| ThreadList::~ThreadList() { |
| // Detach the current thread if necessary. If we failed to start, there might not be any threads. |
| // We need to detach the current thread here in case there's another thread waiting to join with |
| // us. |
| if (Contains(Thread::Current())) { |
| Runtime::Current()->DetachCurrentThread(); |
| } |
| |
| WaitForOtherNonDaemonThreadsToExit(); |
| // TODO: there's an unaddressed race here where a thread may attach during shutdown, see |
| // Thread::Init. |
| SuspendAllDaemonThreads(); |
| } |
| |
| bool ThreadList::Contains(Thread* thread) { |
| return find(list_.begin(), list_.end(), thread) != list_.end(); |
| } |
| |
| bool ThreadList::Contains(pid_t tid) { |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| if ((*it)->tid_ == tid) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| pid_t ThreadList::GetLockOwner() { |
| return Locks::thread_list_lock_->GetExclusiveOwnerTid(); |
| } |
| |
| void ThreadList::DumpForSigQuit(std::ostream& os) { |
| { |
| MutexLock mu(Thread::Current(), *Locks::thread_list_lock_); |
| DumpLocked(os); |
| } |
| DumpUnattachedThreads(os); |
| } |
| |
| static void DumpUnattachedThread(std::ostream& os, pid_t tid) { |
| Thread::DumpState(os, NULL, 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) { |
| DumpNativeStack(os, tid, " native: ", false); |
| } |
| os << "\n"; |
| } |
| |
| void ThreadList::DumpUnattachedThreads(std::ostream& os) { |
| DIR* d = opendir("/proc/self/task"); |
| if (!d) { |
| return; |
| } |
| |
| Thread* self = Thread::Current(); |
| dirent* e; |
| while ((e = readdir(d)) != NULL) { |
| char* end; |
| pid_t tid = strtol(e->d_name, &end, 10); |
| if (!*end) { |
| bool contains; |
| { |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| contains = Contains(tid); |
| } |
| if (!contains) { |
| DumpUnattachedThread(os, tid); |
| } |
| } |
| } |
| closedir(d); |
| } |
| |
| void ThreadList::DumpLocked(std::ostream& os) { |
| os << "DALVIK THREADS (" << list_.size() << "):\n"; |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| (*it)->Dump(os); |
| os << "\n"; |
| } |
| } |
| |
| void ThreadList::AssertThreadsAreSuspended(Thread* self, Thread* ignore1, Thread* ignore2) { |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| if (thread != ignore1 || thread == ignore2) { |
| CHECK(thread->IsSuspended()) |
| << "\nUnsuspended thread: <<" << *thread << "\n" |
| << "self: <<" << *Thread::Current(); |
| } |
| } |
| } |
| |
| #if HAVE_TIMED_RWLOCK |
| // Attempt to rectify locks so that we dump thread list with required locks before exiting. |
| static void UnsafeLogFatalForThreadSuspendAllTimeout(Thread* self) NO_THREAD_SAFETY_ANALYSIS { |
| Runtime* runtime = Runtime::Current(); |
| std::ostringstream ss; |
| ss << "Thread suspend timeout\n"; |
| runtime->DumpLockHolders(ss); |
| ss << "\n"; |
| Locks::mutator_lock_->SharedTryLock(self); |
| if (!Locks::mutator_lock_->IsSharedHeld(self)) { |
| LOG(WARNING) << "Dumping thread list without holding mutator_lock_"; |
| } |
| Locks::thread_list_lock_->TryLock(self); |
| if (!Locks::thread_list_lock_->IsExclusiveHeld(self)) { |
| LOG(WARNING) << "Dumping thread list without holding thread_list_lock_"; |
| } |
| runtime->GetThreadList()->DumpLocked(ss); |
| LOG(FATAL) << ss.str(); |
| } |
| #endif |
| |
| size_t ThreadList::RunCheckpoint(Closure* checkpoint_function) { |
| Thread* self = Thread::Current(); |
| if (kIsDebugBuild) { |
| Locks::mutator_lock_->AssertNotHeld(self); |
| Locks::thread_list_lock_->AssertNotHeld(self); |
| Locks::thread_suspend_count_lock_->AssertNotHeld(self); |
| CHECK_NE(self->GetState(), kRunnable); |
| } |
| |
| std::vector<Thread*> suspended_count_modified_threads; |
| size_t count = 0; |
| { |
| // Call a checkpoint function for each thread, threads which are suspend get their checkpoint |
| // manually called. |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| // TODO: C++0x auto. |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| if (thread != self) { |
| for (;;) { |
| if (thread->RequestCheckpoint(checkpoint_function)) { |
| // This thread will run it's checkpoint some time in the near future. |
| count++; |
| break; |
| } else { |
| // We are probably suspended, try to make sure that we stay suspended. |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| // The thread switched back to runnable. |
| if (thread->GetState() == kRunnable) { |
| continue; |
| } |
| thread->ModifySuspendCount(self, +1, false); |
| suspended_count_modified_threads.push_back(thread); |
| break; |
| } |
| } |
| } |
| } |
| } |
| |
| // Run the checkpoint on ourself while we wait for threads to suspend. |
| checkpoint_function->Run(self); |
| |
| // Run the checkpoint on the suspended threads. |
| for (size_t i = 0; i < suspended_count_modified_threads.size(); ++i) { |
| Thread* thread = suspended_count_modified_threads[i]; |
| if (!thread->IsSuspended()) { |
| // Wait until the thread is suspended. |
| uint64_t start = NanoTime(); |
| do { |
| // Sleep for 100us. |
| usleep(100); |
| } while (!thread->IsSuspended()); |
| uint64_t end = NanoTime(); |
| // Shouldn't need to wait for longer than 1 millisecond. |
| const uint64_t threshold = 1; |
| if (NsToMs(end - start) > threshold) { |
| LOG(INFO) << "Warning: waited longer than " << threshold << " ms for thread suspend" |
| << std::endl; |
| } |
| } |
| // We know for sure that the thread is suspended at this point. |
| thread->RunCheckpointFunction(); |
| { |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| thread->ModifySuspendCount(self, -1, false); |
| } |
| } |
| |
| { |
| // Imitate ResumeAll, threads may be waiting on Thread::resume_cond_ since we raised their |
| // suspend count. Now the suspend_count_ is lowered so we must do the broadcast. |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| Thread::resume_cond_->Broadcast(self); |
| } |
| |
| // Add one for self. |
| return count + suspended_count_modified_threads.size() + 1; |
| } |
| |
| void ThreadList::SuspendAll() { |
| Thread* self = Thread::Current(); |
| |
| VLOG(threads) << *self << " SuspendAll starting..."; |
| |
| if (kIsDebugBuild) { |
| Locks::mutator_lock_->AssertNotHeld(self); |
| Locks::thread_list_lock_->AssertNotHeld(self); |
| Locks::thread_suspend_count_lock_->AssertNotHeld(self); |
| CHECK_NE(self->GetState(), kRunnable); |
| } |
| { |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| { |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| // Update global suspend all state for attaching threads. |
| ++suspend_all_count_; |
| // Increment everybody's suspend count (except our own). |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| if (thread == self) { |
| continue; |
| } |
| VLOG(threads) << "requesting thread suspend: " << *thread; |
| thread->ModifySuspendCount(self, +1, false); |
| } |
| } |
| } |
| |
| // Block on the mutator lock until all Runnable threads release their share of access. |
| #if HAVE_TIMED_RWLOCK |
| // Timeout if we wait more than 30 seconds. |
| if (UNLIKELY(!Locks::mutator_lock_->ExclusiveLockWithTimeout(self, 30 * 1000, 0))) { |
| UnsafeLogFatalForThreadSuspendAllTimeout(self); |
| } |
| #else |
| Locks::mutator_lock_->ExclusiveLock(self); |
| #endif |
| |
| // Debug check that all threads are suspended. |
| AssertThreadsAreSuspended(self, self); |
| |
| VLOG(threads) << *self << " SuspendAll complete"; |
| } |
| |
| void ThreadList::ResumeAll() { |
| Thread* self = Thread::Current(); |
| |
| VLOG(threads) << *self << " ResumeAll starting"; |
| |
| // Debug check that all threads are suspended. |
| AssertThreadsAreSuspended(self, self); |
| |
| Locks::mutator_lock_->ExclusiveUnlock(self); |
| { |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| // Update global suspend all state for attaching threads. |
| --suspend_all_count_; |
| // Decrement the suspend counts for all threads. |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| if (thread == self) { |
| continue; |
| } |
| thread->ModifySuspendCount(self, -1, false); |
| } |
| |
| // Broadcast a notification to all suspended threads, some or all of |
| // which may choose to wake up. No need to wait for them. |
| VLOG(threads) << *self << " ResumeAll waking others"; |
| Thread::resume_cond_->Broadcast(self); |
| } |
| VLOG(threads) << *self << " ResumeAll complete"; |
| } |
| |
| void ThreadList::Resume(Thread* thread, bool for_debugger) { |
| Thread* self = Thread::Current(); |
| DCHECK_NE(thread, self); |
| VLOG(threads) << "Resume(" << *thread << ") starting..." << (for_debugger ? " (debugger)" : ""); |
| |
| { |
| // To check Contains. |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| // To check IsSuspended. |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| DCHECK(thread->IsSuspended()); |
| if (!Contains(thread)) { |
| return; |
| } |
| thread->ModifySuspendCount(self, -1, for_debugger); |
| } |
| |
| { |
| VLOG(threads) << "Resume(" << *thread << ") waking others"; |
| MutexLock mu(self, *Locks::thread_suspend_count_lock_); |
| Thread::resume_cond_->Broadcast(self); |
| } |
| |
| VLOG(threads) << "Resume(" << *thread << ") complete"; |
| } |
| |
| void ThreadList::SuspendAllForDebugger() { |
| Thread* self = Thread::Current(); |
| Thread* debug_thread = Dbg::GetDebugThread(); |
| |
| VLOG(threads) << *self << " SuspendAllForDebugger starting..."; |
| |
| { |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| { |
| MutexLock mu(self, *Locks::thread_suspend_count_lock_); |
| // Update global suspend all state for attaching threads. |
| ++suspend_all_count_; |
| ++debug_suspend_all_count_; |
| // Increment everybody's suspend count (except our own). |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| if (thread == self || thread == debug_thread) { |
| continue; |
| } |
| VLOG(threads) << "requesting thread suspend: " << *thread; |
| thread->ModifySuspendCount(self, +1, true); |
| } |
| } |
| } |
| |
| // Block on the mutator lock until all Runnable threads release their share of access then |
| // immediately unlock again. |
| #if HAVE_TIMED_RWLOCK |
| // Timeout if we wait more than 30 seconds. |
| if (!Locks::mutator_lock_->ExclusiveLockWithTimeout(self, 30 * 1000, 0)) { |
| UnsafeLogFatalForThreadSuspendAllTimeout(self); |
| } else { |
| Locks::mutator_lock_->ExclusiveUnlock(self); |
| } |
| #else |
| Locks::mutator_lock_->ExclusiveLock(self); |
| Locks::mutator_lock_->ExclusiveUnlock(self); |
| #endif |
| AssertThreadsAreSuspended(self, self, debug_thread); |
| |
| VLOG(threads) << *self << " SuspendAll complete"; |
| } |
| |
| void ThreadList::SuspendSelfForDebugger() { |
| Thread* self = Thread::Current(); |
| |
| // The debugger thread must not suspend itself due to debugger activity! |
| Thread* debug_thread = Dbg::GetDebugThread(); |
| CHECK(debug_thread != NULL); |
| CHECK(self != debug_thread); |
| |
| // Collisions with other suspends aren't really interesting. We want |
| // to ensure that we're the only one fiddling with the suspend count |
| // though. |
| MutexLock mu(self, *Locks::thread_suspend_count_lock_); |
| self->ModifySuspendCount(self, +1, true); |
| |
| // Suspend ourselves. |
| CHECK_GT(self->suspend_count_, 0); |
| self->SetState(kSuspended); |
| VLOG(threads) << *self << " self-suspending (debugger)"; |
| |
| // Tell JDWP that we've completed suspension. The JDWP thread can't |
| // tell us to resume before we're fully asleep because we hold the |
| // suspend count lock. |
| Dbg::ClearWaitForEventThread(); |
| |
| while (self->suspend_count_ != 0) { |
| Thread::resume_cond_->Wait(self); |
| if (self->suspend_count_ != 0) { |
| // The condition was signaled but we're still suspended. This |
| // can happen if the debugger lets go while a SIGQUIT thread |
| // dump event is pending (assuming SignalCatcher was resumed for |
| // just long enough to try to grab the thread-suspend lock). |
| LOG(DEBUG) << *self << " still suspended after undo " |
| << "(suspend count=" << self->suspend_count_ << ")"; |
| } |
| } |
| CHECK_EQ(self->suspend_count_, 0); |
| self->SetState(kRunnable); |
| VLOG(threads) << *self << " self-reviving (debugger)"; |
| } |
| |
| void ThreadList::UndoDebuggerSuspensions() { |
| Thread* self = Thread::Current(); |
| |
| VLOG(threads) << *self << " UndoDebuggerSuspensions starting"; |
| |
| { |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| // Update global suspend all state for attaching threads. |
| suspend_all_count_ -= debug_suspend_all_count_; |
| debug_suspend_all_count_ = 0; |
| // Update running threads. |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| if (thread == self || thread->debug_suspend_count_ == 0) { |
| continue; |
| } |
| thread->ModifySuspendCount(self, -thread->debug_suspend_count_, true); |
| } |
| } |
| |
| { |
| MutexLock mu(self, *Locks::thread_suspend_count_lock_); |
| Thread::resume_cond_->Broadcast(self); |
| } |
| |
| VLOG(threads) << "UndoDebuggerSuspensions(" << *self << ") complete"; |
| } |
| |
| void ThreadList::WaitForOtherNonDaemonThreadsToExit() { |
| Thread* self = Thread::Current(); |
| Locks::mutator_lock_->AssertNotHeld(self); |
| bool all_threads_are_daemons; |
| do { |
| { |
| // No more threads can be born after we start to shutdown. |
| MutexLock mu(self, *Locks::runtime_shutdown_lock_); |
| CHECK(Runtime::Current()->IsShuttingDown()); |
| CHECK_EQ(Runtime::Current()->NumberOfThreadsBeingBorn(), 0U); |
| } |
| all_threads_are_daemons = true; |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| // TODO: there's a race here with thread exit that's being worked around by checking if the |
| // thread has a peer. |
| Thread* thread = *it; |
| if (thread != self && thread->HasPeer() && !thread->IsDaemon()) { |
| all_threads_are_daemons = false; |
| break; |
| } |
| } |
| if (!all_threads_are_daemons) { |
| // Wait for another thread to exit before re-checking. |
| thread_exit_cond_.Wait(self); |
| } |
| } while(!all_threads_are_daemons); |
| } |
| |
| void ThreadList::SuspendAllDaemonThreads() { |
| Thread* self = Thread::Current(); |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| { // Tell all the daemons it's time to suspend. |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| // This is only run after all non-daemon threads have exited, so the remainder should all be |
| // daemons. |
| CHECK(thread->IsDaemon()) << *thread; |
| if (thread != self) { |
| thread->ModifySuspendCount(self, +1, false); |
| } |
| } |
| } |
| // Give the threads a chance to suspend, complaining if they're slow. |
| bool have_complained = false; |
| for (int i = 0; i < 10; ++i) { |
| usleep(200 * 1000); |
| bool all_suspended = true; |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| Thread* thread = *it; |
| if (thread != self && thread->GetState() == kRunnable) { |
| if (!have_complained) { |
| LOG(WARNING) << "daemon thread not yet suspended: " << *thread; |
| have_complained = true; |
| } |
| all_suspended = false; |
| } |
| } |
| if (all_suspended) { |
| return; |
| } |
| } |
| LOG(ERROR) << "suspend all daemons failed"; |
| } |
| void ThreadList::Register(Thread* self) { |
| DCHECK_EQ(self, Thread::Current()); |
| |
| if (VLOG_IS_ON(threads)) { |
| std::ostringstream oss; |
| self->ShortDump(oss); // We don't hold the mutator_lock_ yet and so cannot call Dump. |
| LOG(INFO) << "ThreadList::Register() " << *self << "\n" << oss; |
| } |
| |
| // Atomically add self to the thread list and make its thread_suspend_count_ reflect ongoing |
| // SuspendAll requests. |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| MutexLock mu2(self, *Locks::thread_suspend_count_lock_); |
| self->suspend_count_ = suspend_all_count_; |
| self->debug_suspend_count_ = debug_suspend_all_count_; |
| if (self->suspend_count_ > 0) { |
| self->AtomicSetFlag(kSuspendRequest); |
| } |
| CHECK(!Contains(self)); |
| list_.push_back(self); |
| } |
| |
| void ThreadList::Unregister(Thread* self) { |
| DCHECK_EQ(self, Thread::Current()); |
| |
| VLOG(threads) << "ThreadList::Unregister() " << *self; |
| |
| // Any time-consuming destruction, plus anything that can call back into managed code or |
| // suspend and so on, must happen at this point, and not in ~Thread. |
| self->Destroy(); |
| |
| { |
| // Remove this thread from the list. |
| MutexLock mu(self, *Locks::thread_list_lock_); |
| CHECK(Contains(self)); |
| list_.remove(self); |
| } |
| |
| // Delete the Thread* and release the thin lock id. |
| uint32_t thin_lock_id = self->thin_lock_id_; |
| ReleaseThreadId(thin_lock_id); |
| delete self; |
| |
| // Clear the TLS data, so that the underlying native thread is recognizably detached. |
| // (It may wish to reattach later.) |
| CHECK_PTHREAD_CALL(pthread_setspecific, (Thread::pthread_key_self_, NULL), "detach self"); |
| |
| // Signal that a thread just detached. |
| MutexLock mu(NULL, *Locks::thread_list_lock_); |
| thread_exit_cond_.Signal(NULL); |
| } |
| |
| void ThreadList::ForEach(void (*callback)(Thread*, void*), void* context) { |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| callback(*it, context); |
| } |
| } |
| |
| void ThreadList::VisitRoots(Heap::RootVisitor* visitor, void* arg) const { |
| MutexLock mu(Thread::Current(), *Locks::thread_list_lock_); |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| (*it)->VisitRoots(visitor, arg); |
| } |
| } |
| |
| void ThreadList::VerifyRoots(Heap::VerifyRootVisitor* visitor, void* arg) const { |
| MutexLock mu(Thread::Current(), *Locks::thread_list_lock_); |
| for (It it = list_.begin(), end = list_.end(); it != end; ++it) { |
| (*it)->VerifyRoots(visitor, arg); |
| } |
| } |
| |
| uint32_t ThreadList::AllocThreadId() { |
| MutexLock mu(Thread::Current(), allocated_ids_lock_); |
| for (size_t i = 0; i < allocated_ids_.size(); ++i) { |
| if (!allocated_ids_[i]) { |
| allocated_ids_.set(i); |
| return i + 1; // Zero is reserved to mean "invalid". |
| } |
| } |
| LOG(FATAL) << "Out of internal thread ids"; |
| return 0; |
| } |
| |
| void ThreadList::ReleaseThreadId(uint32_t id) { |
| MutexLock mu(Thread::Current(), allocated_ids_lock_); |
| --id; // Zero is reserved to mean "invalid". |
| DCHECK(allocated_ids_[id]) << id; |
| allocated_ids_.reset(id); |
| } |
| |
| } // namespace art |