Thread safety of client

[justbaominh]

Hi,

I'm a bit confused about the thread safety of the Pymodbus client. As mentioned in the documentation:

The client is NOT thread safe, meaning the application must ensure that calls are serialized. This is only a problem for synchronous applications that use multiple threads or for asynchronous applications that use multiple asyncio.create_task. It is allowed to have multiple client objects that, for example, each communicate with a TCP-based device.

Does this mean that running multiple asynchronous client objects is fine, but each individual client should only be called one at a time? Could you confirm if I understand correctly?

Thank you in advance :)

[janiversen]

It means what it says, you cannot have 2 threads each calling the same client object without some sort of lock.

pymodbus do have a locks in place to prevent 2 calls from running simultaneously, but that can easily cause a dead-lock situation in the app code... hence this "safety statement".