Are file mutexes available in Matlab these days?

I'm using Matlab 2016b. I looking at using the Parallel Pool to run a large number of simulations and post processing. The simulations are split into several classes, each with its own Excel result summary file. To ensure I don't get file access issues I want to use mutexes, but I've not been able to find anything about these being available in Matlab. I found some threads on here from people lamenting the lack of mutexes back in 2011, but maybe they have been implemented by now?

I'm aware of more clunky methods of doing this, such as using fopen() to see if the file is already open, but this doesn't give me the same protection a mutex lock would.

[Walter Roberson]

Unfortunately not. But see https://stackoverflow.com/questions/6415283/semaphores-and-locks-in-matlab

Answer 1

[Edric Ellis]

Probably your best bet with the current implementation is to use a DataQueue. The plan would be to have the workers send the information to be saved back to the client using the send method of the DataQueue. The client would use afterEach to react to these incoming messages, and save the data to file. This means that only a single process is ever accessing the files - so no mutex required. Obviously there's cost associated with sending the data from the workers back to the client - but there's also cost involved with using a mutex to wait until it is safe to access the file.

[Ben Wetherill]

I'm trying to initialise teh dataQueue, but I'm getting the error: Undefined variable "parallel" or class "parallel.pool.DataQueue". The parallel pool is running. Do I have to include the DataQueue code somehow?

[Guillaume]

parallel.pool.DataQueue requires R2017a or later, as documented on the bottom of its doc.

[SL: fixed typo in name of the object]

[Ben Wetherill]

Darn! :(