[jira] [Created] (THRIFT-4004) ThreadManager deadlock for task expiration

["Liu Lin (JIRA)" <ji...@apache.org>]

Liu Lin  created THRIFT-4004:
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             Summary: ThreadManager deadlock for task expiration
                 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. 



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