Jamulus 4.0.0beta1 seems to hang occasionally in connect dialog

[ann0see]

Describe the bug

Jamulus 4.0.0 beta1 seems to hang on macOS while fetching the server list. This might be a deadlock
To Reproduce

• Connect to a server
• Open connect dialog via File->connect
• Sometimes observe that Jamulus hangs. This might occur if one switches directories often in the UI

Expected behavior
No hang

Trace

It seems as if the hang might occur in CLMessReadyForSending:

12  QCoreApplication::sendEvent(QObject*, QEvent*) + 172 (QtCore + 625164) [0x107004a0c] 1-12
                                              12  QApplication::notify(QObject*, QEvent*) + 3084 (QtWidgets + 70888) [0x105c494e8] 1-12
                                                12  QApplicationPrivate::notify_helper(QObject*, QEvent*) + 332 (QtWidgets + 64136) [0x105c47a88] 1-12
                                                  12  QWidget::event(QEvent*) + 3200 (QtWidgets + 390252) [0x105c9746c] 1-12
                                                    12  QObject::event(QEvent*) + 672 (QtCore + 929364) [0x10704ee54] 1-12
                                                      12  ??? (Jamulus + 997264) [0x104beb790] 1-12
                                                        12  CProtocol::CreateCLPingWithNumClientsMes(CHostAddress const&, int, int) + 116 (Jamulus + 155652) [0x104b1e004] 1-12
                                                          12  CProtocol::CreateAndImmSendConLessMessage(int, CVector<unsigned char> const&, CHostAddress const&) + 152 (Jamulus + 134384) [0x104b18cf0] 1-12
                                                            12  CProtocol::CLMessReadyForSending(CHostAddress, CVector<unsigned char>) + 56 (Jamulus + 1406932) [0x104c4f7d4] 1-12
                                                              12  ??? (QtCore + 963772) [0x1070574bc] 1-12
                                                                12  ??? (Jamulus + 623968) [0x104b90560] 1-12
                                                                  12  ??? (Jamulus + 624200) [0x104b90648] 1-12
                                                                    12  __sendmsg + 8 (libsystem_kernel.dylib + 27008) [0x18228b980] 1-12
                                                                     *12  ??? (kernel.release.t6041 + 24220) [0xfffffe000b739e9c] 1-12
                                                                       *12  ??? (kernel.release.t6041 + 1923588) [0xfffffe000b909a04] 1-12
                                                                         *12  ??? (kernel.release.t6041 + 7742628) [0xfffffe000be964a4] 1-12
                                                                           *12  ??? (kernel.release.t6041 + 6768432) [0xfffffe000bda8730] 1-12
                                                                             *12  ??? (kernel.release.t6041 + 6767100) [0xfffffe000bda81fc] 1-12
                                                                               *12  sosend + 1044 (kernel.release.t6041 + 6696948) [0xfffffe000bd96ff4] 1-12
                                                                                 *12  ??? (kernel.release.t6041 + 6695552) [0xfffffe000bd96a80] 1-12
                                                                                   *12  ??? (kernel.release.t6041 + 6744736) [0xfffffe000bda2aa0] 1-12
                                                                                     *12  ??? (kernel.release.t6041 + 6334440) [0xfffffe000bd3e7e8] 1-12
                                                                                       *12  lck_mtx_sleep + 212 (kernel.release.t6041 + 481724) [0xfffffe000b7a99bc] 1-12
                                                                                         *12  ??? (kernel.release.t6041 + 590028) [0xfffffe000b7c40cc] 1-12
                                                                                           *12  ??? (kernel.release.t6041 + 595068) [0xfffffe000b7c547c] 1-12

Operating system

macOS 26.5.1

Version of Jamulus

Jamulus 4.0.0 beta1
Additional context

Might be some multithreading bug? Cannot reproduce it consistently for now.

[ann0see]

Could this be related to some corrupt packet or packet loss (I doubt this though)? I switched between Rock/Jazz directories repeatedly and could sometimes cause the hang. If I let the debugger continue, it recovers.

it might hang during sending PROTMESSID_CLM_PING_MS_WITHNUMCLIENTS. It may or may not be related to the recent change to BSD/macOS in send_to_ipv4_with_tos.