is ICU's ucnv_convertEx thread safe?

Question

I'm wondering if ucnv_convertEx in ICU library is thread safe. Looking at source it seems that it is thread-safe, but I'm not 100% sure. Also I can not find explicit state of this in ICU documentation.

Thanks

Answer 1

The ICU User Guide discusses this, for all objects that have an open/close model. Each Converter object must be used in a single thread at a time. If you need more of them, clone them. They're cheap to clone.

By the way, where would you have expected this information? Maybe you could file a ticket, and we can improve the documentation. Thanks.

Answer 2

Basically ICU is thread safe, but:

1. You can't assume that is safe to call const member functions/functions operating on it of same object from different threads (in fact this is generally unsafe which makes ICU tricky in all thread related aspects)
2. Of course you can't use same object with non-cost member function/functions working on object from different threads.

Basically in case of ucnv_convertEx as long as you don't share UConverter between threads it is safe.