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https://issues.apache.org/jira/browse/THRIFT-3768?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15237323#comment-15237323
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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_r59390673
--- 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 --
I made this change and it will only work if I modify each of the thread
implementations to release the smart_ptr to runnable in the thread class after
the thread runs. I assume this is acceptable; once the runnable runs we don't
need the thread smart_ptr holding on to it any more; TServerFramework requires
the TConnectedClient (the runnable) to be destroyed when the client disconnects
to function properly.
> 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
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