When creating UDPSocket instances via CALL WORKER in a shared class constructor, the main thread continues immediately. Using the sockets before the worker completes can lead to undefined behavior like blocked callbacks (e.g., onData) or socket creation failure.

Use a Shared object and Signal to block safely until socket creation finishes

Benefits

• Sockets are fully initialized before any use.
  

• No race conditions in shared class workflows.

Code Example

//Class : MyUDP property listener : 4D.UDPSocket property sender : 4D.UDPSocket property Port : Integer shared Class constructor($options : Object)    This.Port:=(OB Is defined($options; "port")) ? OB Get($options; "port") : 32154    var $socketHolder : Object := New shared object()    Use ($socketHolder)       $socketHolder.listener := Null       $socketHolder.sender := Null       $socketHolder.endOfInitialization := New signal    End use    CALL WORKER("SocketWorker"; Formula($1._initSockets($2)); This; $socketHolder)    $socketHolder.endOfInitialization.wait() // Wait for sockets to be ready    This.listener := $socketHolder.listener    This.sender := $socketHolder.sender //Class function Function _initSockets($socketHolder : Object)    Use ($socketHolder)        $socketHolder.listener:=4D.UDPSocket.new(This.Port; This)        $socketHolder.sender:=4D.UDPSocket.new(0; This)    End use    $socketHolder.endOfInitialization.trigger()