Occurs when two tasks write to a shared memory location. That is, a task writes to a variable with a new value but does not read the same value generated by a prior task.
One of the following has occurred:
|
ID |
Code Location |
Description |
|---|---|---|
|
1 |
Allocation site |
If present, and if the memory involved is heap memory, represents the location and associated call stack when the memory was allocated. |
|
2 |
Parallel site |
If present, represents the location and associated call stack of the parallel site containing the Memory Reuse problem. |
|
3 |
Read |
Represents the instruction and associated call stack of the first access if it is a memory read. |
|
4 |
Write |
Represents the instruction and associated call stack of the second access if it is a memory write. |
|
5 |
Write |
Represents the instruction and associated call stack of the first access if it is a memory write. |
Example
int global;
void main()
{
ANNOTATE_SITE_BEGIN(reuse_site); // Begin parallel site
ANNOTATE_TASK_BEGIN(task111);
global = 111; // Read and/or Write
assert(global == 111);
ANNOTATE_TASK_END();
ANNOTATE_TASK_BEGIN(task222);
global = 222; // Write
assert(global == 222);
ANNOTATE_TASK_END();
ANNOTATE_SITE_END();
}
In this example, two tasks use the same global variable. Each task does not read or communicate the value produced by the other task.
Some Possible Correction Strategies
Change the tasks to have their own private variables rather than sharing a variable.
For more information about interactions between tasks and how to fix them, see the Understanding Data Sharing Problems and the Fixing Sharing Problems sections.
To prevent the Dependencies tool from reporting certain data sharing problems or to request additional analysis for a specific memory region, see the help topic Special-purpose Annotations.