Process A process to create A Shared memory S repeatedly change variable values in the Shared memory S, process B repeatedly read the Shared memory S variable values there is no problem,,,,,,,

But if add A function in the process A, read in the Shared memory S variable values (which means the process and process B can read the Shared memory variable), as long as the process A this function A read the variables,,,,

Problem - & gt; Changes cannot be process A Shared memory

Changes to the Shared memory code is as follows:
if (! Sharememory - & gt; Create (size))//create the Shared memory, the size of the size
{
QDebug () & lt; return ;
}
Display: QSharedMemory: : create already exists.
But the size of 0?

CodePudding user response:

Multiple processes and modify the Shared memory data should be the result of the uncertainty, otherwise, what's the use of the lock

CodePudding user response:

Read A process applied to open the way to open the Shared memory try, or within A process, use the create directly the result of A pointer, don't create any more