Non-on-demand client is only able to handle one connection.

capture/src/capture.cpp

@@ -147,6 +147,11 @@ int main( int argc, char** argv )
             printf( "\nThe client you are trying to connect to uses incompatible protocol version.\nMake sure you are using the same Tracy version on both client and server.\n" );
             return 1;
         }
+        if( handshake == tracy::HandshakeNotAvailable )
+        {
+            printf( "\nThe client you are trying to connect to is no longer able to sent profiling data,\nbecause another server was already connected to it.\nYou can do the following:\n\n  1. Restart the client application.\n  2. Rebuild the client application with on-demand mode enabled.\n" );
+            return 2;
+        }
     }
     while( !worker.HasData() ) std::this_thread::sleep_for( std::chrono::milliseconds( 100 ) );
     printf( "\nQueue delay: %s\nTimer resolution: %s\n", TimeToString( worker.GetDelay() ), TimeToString( worker.GetResolution() ) );

client/TracyProfiler.cpp

@@ -1021,6 +1021,64 @@ void Profiler::Worker()
 
         m_sock->~Socket();
         tracy_free( m_sock );
+
+        // Client is no longer available here
+        for(;;)
+        {
+            if( ShouldExit() )
+            {
+                m_shutdownFinished.store( true, std::memory_order_relaxed );
+                return;
+            }
+
+            while( s_queue.try_dequeue_bulk( token, m_itemBuf, BulkSize ) > 0 ) {}
+            bool lockHeld = true;
+            while( !m_serialLock.try_lock() )
+            {
+                if( m_shutdownManual.load( std::memory_order_relaxed ) )
+                {
+                    lockHeld = false;
+                    break;
+                }
+            }
+            m_serialQueue.swap( m_serialDequeue );
+            if( lockHeld )
+            {
+                m_serialLock.unlock();
+            }
+            m_serialDequeue.clear();
+
+            m_sock = listen.Accept();
+            if( m_sock )
+            {
+                timeval tv;
+                tv.tv_sec = 1;
+                tv.tv_usec = 0;
+
+                char shibboleth[HandshakeShibbolethSize];
+                auto res = m_sock->ReadRaw( shibboleth, HandshakeShibbolethSize, &tv );
+                if( !res || memcmp( shibboleth, HandshakeShibboleth, HandshakeShibbolethSize ) != 0 )
+                {
+                    m_sock->~Socket();
+                    tracy_free( m_sock );
+                    continue;
+                }
+
+                uint32_t protocolVersion;
+                res = m_sock->ReadRaw( &protocolVersion, sizeof( protocolVersion ), &tv );
+                if( !res )
+                {
+                    m_sock->~Socket();
+                    tracy_free( m_sock );
+                    continue;
+                }
+
+                HandshakeStatus status = HandshakeNotAvailable;
+                m_sock->Send( &status, sizeof( status ) );
+                m_sock->~Socket();
+                tracy_free( m_sock );
+            }
+        }
     }
 
     for(;;)

common/TracyProtocol.hpp

@@ -37,6 +37,7 @@ enum HandshakeStatus : uint8_t
     HandshakePending,
     HandshakeWelcome,
     HandshakeProtocolMismatch,
+    HandshakeNotAvailable
 };
 
 enum { WelcomeMessageProgramNameSize = 64 };

server/TracyView.cpp

@@ -460,6 +460,10 @@ bool View::Draw()
     {
         ImGui::OpenPopup( "Protocol mismatch" );
     }
+    else if( status == HandshakeNotAvailable )
+    {
+        ImGui::OpenPopup( "Client not ready" );
+    }
 
     if( ImGui::BeginPopupModal( "Protocol mismatch", nullptr, ImGuiWindowFlags_AlwaysAutoResize ) )
     {
@@ -477,6 +481,22 @@ bool View::Draw()
         ImGui::EndPopup();
     }
 
+    if( ImGui::BeginPopupModal( "Client not ready", nullptr, ImGuiWindowFlags_AlwaysAutoResize ) )
+    {
+#ifdef TRACY_EXTENDED_FONT
+        TextCentered( ICON_FA_LIGHTBULB );
+#endif
+        ImGui::Text( "The client you are trying to connect to is no longer able to sent profiling data,\nbecause another server was already connected to it.\nYou can do the following:\n\n  1. Restart the client application.\n  2. Rebuild the client application with on-demand mode enabled." );
+        ImGui::Separator();
+        if( ImGui::Button( "I understand" ) )
+        {
+            ImGui::CloseCurrentPopup();
+            ImGui::EndPopup();
+            return false;
+        }
+        ImGui::EndPopup();
+    }
+
     return s_instance->DrawImpl();
 }
 

server/TracyWorker.cpp

@@ -1299,6 +1299,7 @@ void Worker::Exec()
     case HandshakeWelcome:
         break;
     case HandshakeProtocolMismatch:
+    case HandshakeNotAvailable:
     default:
         goto close;
     }