On 3/22/2013 2:54 PM, Will Deng wrote:
In our application, we use bit fields a lot. For example:
class data {
unsigned int the_thread_1_data:1;
unsigned int the_thread_2_data:3;
...
};
When one thread is writing to the_thread_1_data, and another thread is
reading or writing to the_thread_2_data, helgrind will flag racing
condition. Is this a known issue in helgrind? Is there a way to get
around this? I believe the operation is multithread safe.
Not safe. Bit fields are generally packed within the same word in
memory, so you now have two threads trying to write the same word
without a mutex.
Try an experiment: remove the field widths, so that each integer will
be in a separate memory word. Helgrind should no longer report an error.
--
David Chapman [email protected]
Chapman Consulting -- San Jose, CA
Software Development Done Right.
www.chapman-consulting-sj.com
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