OpenCV functions are not re-entrant (Bug #2462)
| Status: | Cancelled | Start date: | 2012-10-20 |
|---|---|---|---|
| Priority: | High | Due date: | |
| Assignee: |  Vadim Pisarevsky |
% Done: | 0% |
| Category: | core | ||
| Target version: | 2.4.3 | ||
| Affected version: | Operating System: | ||
| Difficulty: | HW Platform: | ||
| Pull request: |
Description
Several OpenCV functions make use of static const variables for their computations. The problem is that these variables are static. If OpenCV is called in a multi-threaded scenario, several threads may initialize these variables at the same time. The initialization of a static variable is not atomic, in fact it is two operations: Setting an init flag for the variable, then setting the variable itself.
As a result, the first function call in one or more of the threads operates with non-initialized values.
The error in question occured by using OpenCV combined with TBB. Compiler is VS 2010. cv::log() is called on an array of Mat1f within a TBB parallel_for loop.
I did not check which functions other than log() use static variables.
The solution is simple: Get rid of static state of these const variables. In fact, the usage of static here gives no real speed benefit and is a relic of old habits.
Associated revisions
Merge pull request #2462 from ibtaylor:fix_deblurring_calcBlurriness_var_name_typo
History
Updated by Vadim Pisarevsky over 12 years ago
I do not see how the constant tables may affect multi-threaded applications. By definition, they should be initialized before you call cv::log etc. for the first time. If there is a reproducible bug with a particular OpenCV functions, please, submit the corresponding sample. We used cv::log and other such functions in multi-threaded apps for several years without any problems.
- Status changed from Open to Cancelled