[metadata]
id = "CON04-C"
type = "recommendation"
category = "CON"
number = 4
title = "Join or detach threads even if their exit status is unimportant"
description = """
Thethrd_detach()function is used to tell the underlying system that resources
allocated to a particular thread can be reclaimed once it terminates. This
function should be used when a thread's exit status is not required by other
threads (and no other thread needs to usethrd_join()to wait for it to complete).
Whenever a thread terminates without detaching, the thread's stack is
deallocated, but some other resources, including the thread ID and exit status,
are left until it is destroyed by eitherthrd_join()orthrd_detach(). These
resources can be vital for systems with limited resources and can lead to
various "resource unavailable" errors, depending on which critical resource gets
used up first. For example, if the system has a limit (either per-process or
system wide) on the number of thread IDs it can keep track of, failure to
release the thread ID of a terminated thread may lead tothrd_create() being
unable tocreate another thread. This noncompliant code example shows a pool of
threads that are not exited correctly:
"""
severity = "Low"
likelihood = "Unlikely"
priority = "P2"
level = "L3"
cert_version = "2016 Edition (Wiki)"
last_modified = "May 20, 2025"
[rules.cert_c.CON04-C]
enabled = true
[references]
wiki = "https://wiki.sei.cmu.edu/confluence/display/c/CON04-C.+Join+or+detach+threads+even+if+their+exit+status+is+unimportant"