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I was reading somewhere this rule for shared variables "if at least one thread writes to the variable you need a mutex". 

I was always thinking only if more than 1 thread needs write access i need the exclusion. and the simplethread example from the SDK seem to confirm that. Can someone clarify?

I was reading somewhere this rule for shared variables "if at least one thread writes to the variable you need a mutex". 
I was always thinking only if more than 1 thread needs write access i need the exclusion. and the simplethread example from the SDK seem to confirm that. Can someone clarify?


I was reading somewhere this rule for shared variables "if at least one thread writes to the variable you need a mutex". 
I was always think

about-threading-when-to-use-the-mutex-for-shared-variable-access

it is not necessarry to protect data with an mutex if only one thread accesses it.

for max objects: they should be synchronized always because - depending on the object sending the message - this will be executed in a different thread. (time critial objects like metro or delay send in the timer thread.)

https://cycling74.com/tutorials/advanced-max-learning-about-threading

note that there are also read-write locks around. because data needs not to be protected when various thread only read. i'm not sure if max provides rw-locks but it is a good thing for optimizing.

for max objects: they should be synchronized always because - depending on the object sending the message - this will be executed in a different thread.  (time critial objects like metro or delay send in the timer thread.)

here's  a good explanation about this:
https://cycling74.com/tutorials/advanced-max-learning-about-threading

And by accessing you mean write access, right. Thanks for the video link, i've missed that one. I'm making a cup of tea now.

yes. a mutex does not make a difference between read and write. it just locks. but in general you only need protection when doing write access.

but notice a read could internally mean write. refering to the lazy load pattern.

yes. a mutex does not make a difference between read and write. it just locks. but in general you only need protection when doing write access. 

About threading, when to use the mutex for shared variable access