[ https://issues.apache.org/jira/browse/THRIFT-4004?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Liu Lin updated THRIFT-4004: ----------------------------- Description: Set pendingTaskCountMax = 1. Add only 1 worker into ThreadManager. When adding task, set timeout > 0. If there is no task, worker thread will sleep, because `manager_->monitor_.wait`(Line 259) invoked in function `ThreadManager::Worker::run`. Then suppose we have 2 tasks. We add the first task by calling ThreadManager::Impl::add, which will nofity monitor_. But before manager_->monitor_.wait() returns, we call ThreadManager::Impl::add again. If ThreadManager::Impl::add gets lock mutex_ successfully, ThreadManager::Worker::run will fall asleep again because it can not lock mutex_. Now we have tasks_.size() == pendingTaskCountMax_, so ThreadManager::Impl::add will wait on maxMonitor_(Line 462). Becasue the worker cannot fetch a task(because it can not lock mutex_, it will not notify maxMonitor_), so ThreadManager::Impl::add will wait forever. Now both the two threads wait for each other, result in deadlock. was: Set pendingTaskCountMax = 1. Add only 1 worker into ThreadManager. When adding task, set timeout > 0. If there is no task, worker thread will sleep, because manager_->monitor_.wait(Line 259) invoked in function ThreadManager::Worker::run. Then suppose we have 2 tasks. We add the first task by calling ThreadManager::Impl::add, which will nofity monitor_. But before manager_->monitor_.wait() returns, we call ThreadManager::Impl::add again. If ThreadManager::Impl::add gets lock mutex_ successfully, ThreadManager::Worker::run will fall asleep again because it can not lock mutex_. Now we have tasks_.size() == pendingTaskCountMax_, so ThreadManager::Impl::add will wait on maxMonitor_(Line 462). Becasue the worker cannot fetch a task(because it can not lock mutex_, it will not notify maxMonitor_), so ThreadManager::Impl::add will wait forever. Now both the two threads wait for each other, result in deadlock. > ThreadManager deadlock when adding new task > ------------------------------------------- > > Key: THRIFT-4004 > URL: https://issues.apache.org/jira/browse/THRIFT-4004 > Project: Thrift > Issue Type: Bug > Components: C++ - Library > Affects Versions: 0.9.3 > Reporter: Liu Lin > > Set pendingTaskCountMax = 1. > Add only 1 worker into ThreadManager. > When adding task, set timeout > 0. > If there is no task, worker thread will sleep, because > `manager_->monitor_.wait`(Line 259) invoked in function > `ThreadManager::Worker::run`. > Then suppose we have 2 tasks. We add the first task by calling > ThreadManager::Impl::add, which will nofity monitor_. But before > manager_->monitor_.wait() returns, we call ThreadManager::Impl::add again. If > ThreadManager::Impl::add gets lock mutex_ successfully, > ThreadManager::Worker::run will fall asleep again because it can not lock > mutex_. > Now we have tasks_.size() == pendingTaskCountMax_, so > ThreadManager::Impl::add will wait on maxMonitor_(Line 462). Becasue the > worker cannot fetch a task(because it can not lock mutex_, it will not notify > maxMonitor_), so ThreadManager::Impl::add will wait forever. > Now both the two threads wait for each other, result in deadlock. -- This message was sent by Atlassian JIRA (v6.3.4#6332)