program locked at `__lll_lock_wait_private`

[zxx8808]

The call stack is as follows, I think it's because I use a timer( created using timer_create) in my program, so the program interlocks at the following two red boxes.

Instead of using a system timer, the approach I came up with is to get the current time and the last time. If their difference is greater than a certain value, then do the things I want to do. Maybe this timer is not very accurate.

Want to ask:

1. Does open62541 support multi-thread now?
2. Any suggestions?

Used CMake options:

cmake .. -DUA_ENABLE_AMALGAMATION=ON -DUA_ENABLE_DISCOVERY=ON -DUA_ENABLE_DISCOVERY_MULTICAST=ON -DUA_NAMESPACE_ZERO=ON

Checklist

Please provide the following information:

• [x] open62541 Version (release number or git tag): branch : 1.3, commit : cb6fd614daea6a0
• [ ] Other OPC UA SDKs used (client or server):
• [x] Operating system: centos
• [ ] Logs (with UA_LOGLEVEL set as low as necessary) attached
• [ ] Wireshark network dump attached
• [ ] Self-contained code example attached
• [ ] Critical issue

[zxx8808]

When I config the cmake option UA_MULTITHREADING=100, the program stops at an assertion ++(lock->mutexCounter) == 1.

The call stack below shows the two places where the mutex is locked at. I don't know why UA_LOCK(&server->serviceMutex) is already used in periodicServerRegister, UA_LOCK in __UA_Server_read can still go on to assert. Why isn't it stopped at pthread_mutex_lock(&lock->mutex)?