Multithreading in CPP

This repository has two objectives:

• Demonstrate the concepts of multiple threading/concurrency through code samples.
• Demonstrate the C++ multi-threading concepts through code samples.

Some of the concepts demonstrated

1. A simple usage of threads: threads.cpp
2. Collecting return values from threads: return_from_function.cpp
3. Data race occurs when two or more threads are trying to manipulate same shared data at the same time: data_race.cpp
4. Different types of locking mechanisms: locking.cpp
5. Counters should work regardless of how many threads are accessing it. See thread_safe_counters.cpp
6. Check if a function completes within stipulated time or not: timeouts.cpp
7. Syncing cameras to take pictures simultaneously:
   • sync_devices_yeild.cpp
   • sync_devices_condition_variable.cpp
8. What are deadlocks and how do they happen? deadlock.cpp

Upcoming

• Consumer producer pattern for threads
• Using threadpool to avoid creating threads

Some common threading mistakes and notes

• Trying to join a detached thread or thread that has already been joined. Under uncertainty, use thread member "joinable" to check if thread can be joined or not.
• Trying to acquire a mutex twice.
• Everything is passed by value. Use std::ref to pass argument by reference.
• Unlocked shared data members cause data race if their value is manipulated by threads.
• When using mutex::lock() and mutex::unlock(), forgetting to unlock will cause the resource to not be released.