pthread_attr_init / pthread_attr_destroy / pthread_attr_getdetachstate / pthread_attr_setdetachstate (3) - glibc

Split from the chapter glibc: Threads into the per-function layout; see the method page and the glibc ledger for coverage status.

Declaration and gates

#include <pthread.h>

int pthread_attr_init(pthread_attr_t *attr);                      /* :285 */
int pthread_attr_destroy(pthread_attr_t *attr);                   /* :288 */
int pthread_attr_getdetachstate(const pthread_attr_t *attr,
                                int *detachstate);                /* :292 */
int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate);
                                                                  /* :297 */

No feature-test gate: the four declarations sit in the always-visible part of pthread.h (/usr/include/pthread.h lines 285-300). The other attribute setters are covered in pthread-attr-affinity-sigmask-np and the full-family view in pthread-attr-family.

Semantics

pthread_attr_init fills an opaque pthread_attr_t with the default attribute values; re-initializing an already initialized object is undefined behavior (pthread_attr_init(3)). pthread_attr_destroy releases any resources and has no effect on threads already created from the object; a destroyed object may be re-initialized, and any other use is undefined. pthread_attr_setdetachstate stores PTHREAD_CREATE_JOINABLE (the default) or PTHREAD_CREATE_DETACHED, deciding whether threads created from attr must be joined or clean themselves up; pthread_attr_getdetachstate reads it back. All four return 0 on success or a nonzero error number.

Gotchas and portability

• A joinable thread that is never joined or detached leaks its resources (pthread_attr_setdetachstate(3) NOTES).
• POSIX.1 documents ENOMEM for pthread_attr_init; on Linux these calls always succeed (pthread_attr_init(3) ERRORS).
• musl 1.2.5: setter musl src/thread/pthread_attr_setdetachstate.c, getters bundled in musl src/thread/pthread_attr_get.c.

References

• man3: pthread_attr_init(3), pthread_attr_setdetachstate(3) (source-cache/man-pages-sparse/man3/)
• glibc manual: threads.texi, node Creating and Destroying Threads
• header: /usr/include/pthread.h lines 281-300
• symbols: nm -D --with-symbol-versions libc.so.6