To: J3 Members J3/17-116r1 From: Van Snyder & Jon Steidel & Daniel Chen & Anton Shterenlikht Subject: Question without edits concerning collective subroutines References: 17-007 Date: 2017 February 14 1. Question: 16.6p1 says a collective subroutine shall be invoked by the same statement on all active images of the current team. If it's invoked from a recursive procedure, does it matter from which instance it is invoked on different images? This should be made clear, one way or another, even if only in a note. 2. Response: The answer to the question is NO. The instance should not matter. All that matters is that the same collective subroutine must be invoked in the same sequence by all active images of the current team. This normative text already has this [345:17-18] 16.6p2: "... the sequence of invocations of collective subroutines shall be the same on all active images of a team." The existing wording already covers a situation where different active images of a team invoke a collective subroutine by the same statement in different iterations of a recursive procedure. Consider a team of 4 images: 1, 2, 3 and 4. Odd images of this team invoke a collective subroutine in instances 1 and 3 of a recursive procedure, and even images of the same team invoke the same collective subroutine by the same statement in instances 2 and 4 of a recursive procedure. In this case the sequence of invocations of collective subroutine is the same on all active images of a team. So is a conforming behaviour. We conclude that no edit is needed to the normative text and no note is needed.