To: J3 09-119r2 From: Bill Long Subject: Files connected to more than one unit Date: 2009 February 11 References: J3/09-007 Discussion: Output on the units OUTPUT_UNIT or ERROR_UNIT on every image are normally expected to display on the same device (such as a terminal screen) or be redirected to the same physical file. Whole records from the images are to be interleaved into one stream of text, to enhance readability. In 09-007 there is a contradiction in that OUTPUT_UNIT is connected to the same file for all images ([206:22-23]) with a similar rule for ERROR_UNIT ([206:26]), and that more than one unit cannot be connected to the same file ([207:26-27]). One resolution of the contradiction is to change the text so that OUTPUT_UNIT and ERROR_UNIT are exceptions to the rule that multiple units (one from each image) cannot be connected to a single file. This option is consistent with the design of parallel I/O that was originally proposed and later removed for future reconsideration. It also matches what actually happens in some implementations. Edits for this option are in 09-119r1. Another option is to have seaprate files, one pair for each image, and add a Note that the processor is expected to do the right thing with these files, effectively as a postprocessing step. This option maintains the current (f03) standard design while still allowing implemenations to continue doing what already happens with output from MPI and OpenMP programs. Edits for this option are provided in this paper. Edits to 09-007: [206:22-23] In 9.5.1 Referring to a file, para 4, sentence 3, delete "to the same file on all images". [206:26] In 9.5.1 Referring to a file, para 5, sentence 2, delete "to the same file on all images". [206:18+] At the end of 9.5.1 Referring to a file, add a new Note: "Note 9.14a Even though OUTPUT_UNIT is connected to a separate file on each image, it is expected that the processor will merge the sequences of records from these files into a single sequence of records that is sent to the physical device associated with this unit, such as the user's terminal. If ERROR_UNIT is associated with the same physical device, the sequences of records from files connected to ERROR_UNIT on each of the images should be merged into the same sequence generated from the OUTPUT_UNIT unit files. Otherwise, the sequence of records in the files connected to ERROR_UNIT on each image should be merged into its own sequence of records that is sent to the physical device associated with ERROR_UNIT."