J3/10-176
To: J3
From: Malcolm Cohen
Subject: DO CONCURRENT (Interp=3) output interleaving.
Date: 2010 June 02

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NUMBER:
TITLE: DO CONCURRENT and output interleaving
KEYWORDS: DO CONCURRENT, output
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

Consider the trivial example:

  DO CONCURRENT (i=1:1)
    PRINT *,'Line 1'
    PRINT *,'Line 2'
  END DO

According to the ultimate bullet point of 8.1.6.7, the output records
appear in an indeterminate order, therefore it appears that the
processor is permitted to produce the output
 Line 2
 Line 1
for that program fragment.

Q1. Is this intentional?

Also, this ordering statement appears as a bullet point belonging to
  "The following additional restrictions apply to execution of a DO
   CONCURRENT construct."
but it is not a restriction, either on the user or on the processor
(rather the opposite of a restriction on the processor).

Q2. Should this not be a separate paragraph to avoid confusion?

ANSWER:

A1. No, this was not intentional.  An edit is supplied to correct
    this.

A2. Yes, this should not have been a bullet point as it does not
    belong in the list of restrictions.

EDITS to 10-007:

[178:17-18] Delete the last bullet point of 8.1.6.7.

[178:18+] Insert new paragraph
  "If records are written to a sequential file by more than one
   iteration, the ordering between records written by different
   iterations is indeterminate."
{This leaves the statement within the subclause entitled "Restrictions
 on ..." which is suboptimal but not an actual contradiction.}

SUBMITTED BY: Malcolm Cohen

HISTORY: 10-176   m192 Submitted

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