Are global variables accessed atomically?

[Guillermo]

Hello,

My EA will have various instances running on different pairs. Once a day, I would like to check the existence of new files in some directory. If they exist, I would like to relaunch all the instances, but just once.

I was thinking to implement it using global variables, however, from the documentation, they seem not to grant atomic access. How could I achieve it?

Best regards.

[rod178]

https://docs.mql4.com/globals/globalvariableget

[Drazen Penic]

Use GlobalVariableSetOnCondition()

Excerpt from the documentation:

Function provides atomic access to the global variable, so it can be used for providing of a mutex at interaction of several Expert Advisors working simultaneously within one client terminal. 

[William Roeder]

See my mutex Prevent EA from opening trades at the same time across 2 or more pairs? (Steve) - MQL4 forum