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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