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This article mainly explains "linux how to judge the existence of threads", the content of the explanation is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "linux how to judge the existence of threads" bar!

In mysql, the "pthread_kill ()" function can be used to determine whether a thread exists. This function can send a sig signal to the thread of the specified ID to determine whether the thread is still alive or not. The syntax is "int pthread_kill (pthread_t thread, int sig)".

The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

How does linux determine whether a thread exists?

Pthread_kill:

Don't be intimidated by the name, pthread_kill is not a kill, but sends a signal to a thread. Remember signal, the default action of most signal is to terminate the running of the process, so we use signal () to grab the signal and add the handler function.

Int pthread_kill (pthread_t thread, int sig)

Send a sig signal to the specified ID thread, if there is no processing in the thread code, then the default behavior of the signal affects the whole process, that is, if you send SIGQUIT to a thread, but the thread does not implement the signal handler function, the whole process exits.

Pthread_kill (threadid, SIGKILL), too, kills the entire process.

If you want to get the correct behavior, you need to implement signal (SIGKILL,sig_handler) in the thread.

So, if the parameter of int sig is not 0, you must know exactly what to do, and you must implement the signal handling function of the thread, otherwise, it will affect the whole process.

OK, if int sig is 0, this is a reserved signal, and one function is to determine whether the thread is still alive.

Let's take a look at the return value of pthread_kill:

Success: 0

Thread does not exist: ESRCH

Illegal signal: EINVAL

So, pthread_kill (threadid,0) is very useful.

The above code can determine whether the thread is still alive.

Thank you for your reading, the above is the content of "how to judge the existence of threads in linux". After the study of this article, I believe you have a deeper understanding of how to judge the existence of threads in linux, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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