What is pdh locking?

PDH locking is a technique used in computer systems to prevent race conditions that may occur in multithreaded systems. PDH (Perfmon Data Helper) is a component in the Windows operating system that provides performance monitoring and counter data for application developers and system administrators.

Locking mechanisms are used in multithreaded systems to ensure that multiple threads do not simultaneously access the same resource, such as a variable or a file. PDH locking is a type of locking that prevents multiple threads from simultaneously accessing the PDH counter data.

When multiple threads attempt to access PDH counters without appropriate locking, it may result in race conditions. A race condition occurs when the order in which threads access the same resource determines the final output of the program. It can cause incorrect results, unpredictable behavior, or even crashes.

PDH locking uses a mutual exclusion mechanism to ensure that only one thread at a time can access the PDH counters. This is done by providing a lock object that threads must acquire before accessing the counters. If a thread attempts to acquire the lock when it is already held by another thread, it will block until the lock is released.

Overall, PDH locking is an important technique for developers and system administrators to ensure the accuracy and reliability of performance monitoring data in their applications and systems.