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ASF GitHub Bot commented on THRIFT-3768: ---------------------------------------- Github user tpcwang commented on a diff in the pull request: https://github.com/apache/thrift/pull/980#discussion_r59304879 --- Diff: lib/cpp/src/thrift/server/TThreadedServer.h --- @@ -83,12 +88,56 @@ class TThreadedServer : public TServerFramework { virtual void serve(); protected: + /** + * Drain recently connected clients by joining their threads - this is done lazily because + * we cannot do it inside the thread context that is disconnecting. + */ + virtual void drainDeadClients(); + + /** + * Implementation of TServerFramework::onClientConnected + */ virtual void onClientConnected(const boost::shared_ptr<TConnectedClient>& pClient) /* override */; - virtual void onClientDisconnected(TConnectedClient* pClient) /* override */; + + /** + * Implementation of TServerFramework::onClientDisconnected + */ + virtual void onClientDisconnected(TConnectedClient *pClient) /* override */; boost::shared_ptr<apache::thrift::concurrency::ThreadFactory> threadFactory_; - apache::thrift::concurrency::Monitor clientsMonitor_; + + /** + * A helper wrapper used to wrap the client in something we can use to maintain + * the lifetime of the connected client within a detached thread. --- End diff -- It's not a detached thread anymore, but why is this needed? I think ClientMap be a map from TConnectedClient* to shared_ptr<apache:thrift::concurrency::Thread> because Thread itself holds on to the TConnectedClient and maintains its lifetime since it needs to run it. > 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)