Thread creation is easy. Call std::thread, and a new thread will be created. The thread gets a work package and starts it immediately. The creator of the thread (the Parent) has to take care of the created thread (the child). The parent should wait until their child completes their task or has to detach himself from the child. The child thread can get its payload task arguments by copy or by reference.
That was too fast. So the details will follow.
Creation and execution of a thread
Now, a more formal approach: a thread gets a Callable and starts it immediately.
This sentence needs a few notes.
- A Callable is an entity that behaves like a function. It can be a function, a function object, or a lambda function.
- A function object is an instance of a class for which the call operator is overloaded. The key difference between functions and function objects is that a function object can have a state.
- A lambda (anonymous function) is a pure function body without a name. It can be invoked just in place. A lambda function can capture its calling context. That’s why they are often called closures.
After the theory, a small example.
All threads – t1, t2, and t3 – write their messages to the console. The work package of thread t2 is a function object (lines 10 – 15), and the work package of thread t3 is a lambda function (line 29). In lines 32 – 34, the Main thread or Parent waits until his children are done.
Let’s have a look at the output. This is more interesting.
The two programs’ execution results differ in two aspects. First, child threads will be executed in a different order. Second, the output is a little bit of a mess. So, in the second run, the line break of the function helloFunction happens after the lambda function call.
The next article will be about the lifetime of a thread. (Proofreader Alexey Elymanov)
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Thanks, in particular, to Jon Hess, Lakshman, Christian Wittenhorst, Sherhy Pyton, Dendi Suhubdy, Sudhakar Belagurusamy, Richard Sargeant, Rusty Fleming, John Nebel, Mipko, Alicja Kaminska, Slavko Radman, and David Poole.
|My special thanks to Embarcadero|
|My special thanks to PVS-Studio|
|My special thanks to Tipi.build|
|My special thanks to Take Up Code|
I’m happy to give online seminars or face-to-face seminars worldwide. Please call me if you have any questions.
- Embedded Programmierung mit modernem C++ 12.12.2023 – 14.12.2023 (Präsenzschulung, Termingarantie)
Standard Seminars (English/German)
Here is a compilation of my standard seminars. These seminars are only meant to give you a first orientation.
- C++ – The Core Language
- C++ – The Standard Library
- C++ – Compact
- C++11 and C++14
- Concurrency with Modern C++
- Design Pattern and Architectural Pattern with C++
- Embedded Programming with Modern C++
- Generic Programming (Templates) with C++
- Clean Code with Modern C++
- Phone: +49 7472 917441
- Mobil:: +49 176 5506 5086
- Mail: schulung@ModernesCpp.de
- German Seminar Page: www.ModernesCpp.de
- Mentoring Page: www.ModernesCpp.org
Modernes C++ Mentoring,