<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">The original threads spec for Modula-3 does not mention join can only run once. The only mention is in Thread.i3.<div><br></div><div>I agree that it seems silly to join twice. On the other hand, Java semantics does not prohibit multiple joins.<br><div><br><div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; 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The existing implementations all either support multiple join or have to go out of<br><br>their way to prevent it. Yet Thread.i3 has been commented so presumably forever.<br><br><br><br> - Jay<br><br><br><br><br>Date: Tue, 3 Nov 2009 09:36:23 -0500<br>From: <a href="mailto:rcoleburn@scires.com">rcoleburn@scires.com</a><br>To: <a href="mailto:m3devel@elegosoft.com">m3devel@elegosoft.com</a><br>Subject: Re: [M3devel] join twice?<br><br><br>I think the comment in the code is correct.<br><br>Semantically, it doesn't make sense to join a thread more than once. Join is the compliment to Fork. With fork, one thread becomes two. With Join, two threads become one. After they've become one, the 2nd thread is no more, so you can't join to it anymore.<br><br>IMO, the implementation should enforce this behavior. What would be the "benefit" of allowing more than one join? What does it "mean" to join a "dead thread"?<br><br>Regards,<br>Randy Coleburn<br><br><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Tony Hosking <<a href="mailto:hosking@cs.purdue.edu">hosking@cs.purdue.edu</a>> 11/2/2009 11:54 PM >>><br></blockquote></blockquote></blockquote><br><br><br><br>OK, sure. Fair enough.<br><br><br>On 2 Nov 2009, at 16:43, Jay K wrote:<br><br><blockquote type="cite">(Whether the implementation actually prohibits it or not is an implementation decision.) <br></blockquote><br>Tony, I'm sympathetic to the smaller version but I think it is wrong.<br>"It is a checked runtime error to call this more than once for any t"<br>is a much different/stronger statement than e.g.<br>"it is implementation defined what happens if you call join more than once for any t".<br>The printed Reactor 4.1 docs have the same comment as current Thread.i3.<br><br>You know, ideally if I write:<br>Thread.Join(t);<br>Thread.Join(t);<br><br>and it works today on any system, it will continue to work on all systems</div></blockquote></div><br></div></div></body></html>