Date: Sat, 15 Mar 2003 01:12:44 -0800 From: David Schultz <das@FreeBSD.ORG> To: David Xu <davidxu@FreeBSD.ORG> Cc: John Baldwin <jhb@FreeBSD.ORG>, cvs-all@FreeBSD.ORG, cvs-src@FreeBSD.ORG, src-committers@FreeBSD.ORG Subject: Re: cvs commit: src/lib/libpthread/thread thr_rwlock.c Message-ID: <20030315091244.GB25766@HAL9000.homeunix.com> In-Reply-To: <200303150347.h2F3lLjK069888@freefall.freebsd.org> References: <200303150347.h2F3lLjK069888@freefall.freebsd.org>
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Thus spake David Xu <davidxu@FreeBSD.org>: > This design prevents a thread to get a reader lock recursively when > there is a writter blocked on a rwlock. You're right in that the standard blesses the practice of a reader recursing on a lock. Glancing briefly at the code, it looks like we presently deadlock if a writer is waiting. However, the fix is not so trivial. Writers *must* be given priority over readers within a bounded amount of time or they will be starved. Consider what happens when you have a neverending stream of readers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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