Editing Thread safety (section)

==Levels of thread safety==
Different vendors use slightly different terminology for thread-safety,<ref>{{cite web|url=https://www.ibm.com/docs/en/i/7.5?topic=safety-api-thread-classifications |title=API thread safety classifications |publisher=IBM |date=2023-04-11 |access-date=2023-10-09}}</ref> but the most commonly used thread-safety terminology are:<ref name=":1">{{cite web |last=Oracle |date=2010-11-01 |title=Oracle: Thread safety |url=https://docs.oracle.com/cd/E37838_01/html/E61057/compat-14994.html#scrolltoc |access-date=2013-10-16 |publisher=Docs.oracle.com |postscript="A procedure is thread safe when the procedure is logically correct when executed simultaneously by several threads"; "3 level of thread-safe"}}</ref>
*'''Not thread safe''': Data structures should not be accessed simultaneously by different threads.
*'''Thread safe, serialization''': Uses '''a single mutex for all resources''' to guarantee the thread to be free of [[race condition#Computing|race conditions]] when those resources are accessed by multiple threads simultaneously.
*'''Thread safe, MT-safe''': Uses '''a mutex for every single resource''' to guarantee the thread to be free of [[race condition#Computing|race conditions]] when those resources are accessed by multiple threads simultaneously.

Thread safety guarantees usually also include design steps to prevent or limit the risk of different forms of [[deadlock (computer science)|deadlock]]s, as well as optimizations to maximize concurrent performance. However, deadlock-free guarantees cannot always be given, since deadlocks can be caused by [[callback (computer programming)|callbacks]] and violation of [[architectural layer]]ing independent of the library itself.

[[Library (computing)|Software libraries]] can provide certain thread-safety guarantees.<ref>{{Cite web |title=MT Safety Levels for Libraries |url=https://docs.oracle.com/cd/E37838_01/html/E61057/compat-89113.html#scrolltoc |access-date=2024-05-17 |website=Docs Oracle}}</ref> For example, concurrent reads might be guaranteed to be thread-safe, but concurrent writes might not be. Whether a program using such a library is thread-safe depends on whether it uses the library in a manner consistent with those guarantees.