[ 
https://issues.apache.org/jira/browse/THRIFT-3768?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15247728#comment-15247728
 ] 

ASF GitHub Bot commented on THRIFT-3768:
----------------------------------------

Github user jeking3 commented on a diff in the pull request:

    https://github.com/apache/thrift/pull/980#discussion_r60227644
  
    --- Diff: lib/cpp/src/thrift/server/TThreadedServer.cpp ---
    @@ -90,31 +95,69 @@ TThreadedServer::~TThreadedServer() {
     }
     
     void TThreadedServer::serve() {
    +  threadFactory_->setDetached(false);
       TServerFramework::serve();
     
    -  // Drain all clients - no more will arrive
    -  try {
    -    Synchronized s(clientsMonitor_);
    -    while (getConcurrentClientCount() > 0) {
    -      clientsMonitor_.wait();
    -    }
    -  } catch (TException& tx) {
    -    string errStr = string("TThreadedServer: Exception joining workers: ") 
+ tx.what();
    -    GlobalOutput(errStr.c_str());
    +  // Ensure post-condition of no active clients
    +  Synchronized s(clientMonitor_);
    +  while (!activeClientMap_.empty()) {
    +    clientMonitor_.wait();
    +  }
    +
    +  drainDeadClients();
    +}
    +
    +void TThreadedServer::drainDeadClients() {
    +  // we're in a monitor here
    +  while (!deadClientMap_.empty()) {
    +    ClientMap::iterator it = deadClientMap_.begin();
    +    it->second->join();
    +    deadClientMap_.erase(it);
       }
     }
     
     void TThreadedServer::onClientConnected(const 
shared_ptr<TConnectedClient>& pClient) {
    -  threadFactory_->newThread(pClient)->start();
    +  Synchronized sync(clientMonitor_);
    +  activeClientMap_.insert(ClientMap::value_type(pClient.get(), 
boost::make_shared<TConnectedClientRunner>(pClient)));
    +  ClientMap::iterator it = activeClientMap_.find(pClient.get());
    --- End diff --
    
    I implemented this suggestion.


> TThreadedServer may crash if it is destroyed immediately after it returns 
> from serve(); TThreadedServer disconnects clients when they connec
> --------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: THRIFT-3768
>                 URL: https://issues.apache.org/jira/browse/THRIFT-3768
>             Project: Thrift
>          Issue Type: Bug
>          Components: C++ - Library
>    Affects Versions: 0.9.3
>            Reporter: Ted Wang
>            Assignee: James E. King, III
>            Priority: Minor
>
> Here's a sequence that shows the race:
> Thread-1 (Users of TThreadedServer): Calls TThreadedServer::stop(), which 
> calls interruptChildren and initiates the tearing down of client connections.
> Thread-2: In TServerFramework::serve(), broke out of accept, and now blocks 
> in TThreadedServer::serve() waiting to drain all the clients.
> Thread-3 (The connected client thread created by TThreadedServer): In 
> disposeConnectedClient, running because the server is shutting down and the 
> shared_ptr specified this function to be the cleanup function for the client. 
> This thread just returned from onClientDisconnected and now context switches.
> Thread-2: TThreadedServer::serve() is notified that all of the clients have 
> disconnected and completes.
> Thread-1: Joins on Thread-2 and destroys the server object because it is done.
> Thread-3: Finally gets a chance to run, but now encounters undefined behavior 
> because it is still executing a member function of an object that has been 
> destroyed.
> You can force this race in action if you put sleep(1) before 
> onClientDisconnected() in disposeConnectedClient



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Reply via email to