pthread_detach(3)

✨ NAME ✨

pthread_detach — detach a thread 🧵💖

okay so we're in the pthread_detach(3) part of the manual, bestie, and this one is genuinely so useful it's not even funny.

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📚 LIBRARY 📚

This lives in the POSIX threads library — that's libpthread, and you link it with -lpthread. 🫶

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🎀 SYNOPSIS 🎀

#include <pthread.h>

int pthread_detach(pthread_t thread);

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💫 DESCRIPTION 💫

So pthread_detach() is the function that marks the thread identified by thread as detached. that's it, that's the whole vibe. ✨

And when a detached thread terminates, its resources are automatically released back to the system — no need for another thread to come along and join with the terminated thread. it's giving self-cleaning, it's giving low-maintenance queen. 👑

real talk though: attempting to detach an already detached thread results in unspecified behavior. don't do it. the standard literally will not tell you what happens, and that's terrifying fr fr. 💀

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🍓 RETURN VALUE 🍓

• On success, pthread_detach() returns 0 ⭐
• On error, it returns an error number 🙈

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🔥 ERRORS 🔥

• EINVAL — thread is not a joinable thread. nope, wrong kind of thread, sorry bestie 💅
• ESRCH — No thread with the ID thread could be found. it's not there! nowhere! gone! 😭

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🦋 ATTRIBUTES 🦋

For an explanation of the terms used in this section, see attributes(7). (iykyk 📖✨)

• Interface: pthread_detach()
• Attribute: Thread safety
• Value: MT-Safe

so it's MT-Safe, meaning go off, call it from multiple threads, she's fine. 🫶

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👑 STANDARDS 👑

POSIX.1-2008. certified, official, iconic.

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🌸 HISTORY 🌸

POSIX.1-2001. yeah she's been around, an OG. 🎀

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🌈 NOTES 🌈

• Once a thread has been detached, it can't be joined with pthread_join(3) or be made joinable again. that door is CLOSED, bestie. periodt. 🚪💅
• A new thread can be created in a detached state using pthread_attr_setdetachstate(3) to set the detached attribute of the attr argument of pthread_create(3). so you can have it detached from day one, main character energy from birth. ✨
• The detached attribute merely determines the behavior of the system when the thread terminates; it does not prevent the thread from being terminated if the process terminates using exit(3) — or equivalently, if the main thread returns. so like, it's not a shield, it's a cleanup policy. important distinction. 💀
• Either pthread_join(3) or pthread_detach() should be called for each thread that an application creates, so that system resources for the thread can be released. basically pick one, don't ghost your threads. 🙈

but note that the resources of any threads for which one of these actions has not been done will be freed when the process terminates. so like… it works out eventually, but don't test it.

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🧚 EXAMPLES 🧚

The following statement detaches the calling thread:

pthread_detach(pthread_self());

look at her. detaching herself. self-care. we love to see it. 🫶✨

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💜 SEE ALSO 💜

• pthread_attr_setdetachstate(3)
• pthread_cancel(3)
• pthread_create(3)
• pthread_exit(3)
• pthread_join(3)
• pthreads(7)

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and that's the whole page, bestie!! 💖 this came from Linux man-pages 6.20, dated 2025-05-17 — go read the other pthread pages, ily, stay joined (unless you detach, which is also valid). 🎀🦋✨