Charm++ parallel programming system

["Mitchell, John A" <jamitch AT sandia.gov>]

Thanks.  

OK -- I have already done the reduction.  Its not too much trouble.  

John

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From: unmobile AT gmail.com <unmobile AT gmail.com> on behalf of Phil Miller <mille121 AT illinois.edu>
Sent: Wednesday, June 14, 2017 3:23 PM
To: Mitchell, John A
Cc: charm AT lists.cs.illinois.edu
Subject: [EXTERNAL] Re: [charm] array length after dynamic insertion 'doneInserting()'

 

Hi John,

There's no provided API to get the number of elements in a dynamic array (*). We would have to do exactly the same reduction as user code, which presents some issues:

- It adds overhead for use cases that don't need the runtime system to tell the application the number of elements inserted

- When would that API be safe to call? Would doneInserting have to be a blocking call, or take a callback, to indicate when the value is available?

Given that this is something we expect the application code to have a straightforward time implementing for its specific insertion logic, that seems preferable. I'd be interested to hear about cases where doing it in the application is complicated or hard.

(*) Note that I say "number of elements" and not "length", because the population of the array need not be a dense, contiguous set of indices. It can be arbitrarily sparse. We could nominally distinguish 'chare arrays' (elements named by all indices within a k-dimensional rectangle) from 'chare sets' (elements named by an arbitrary set of indices)

Phil

On Wed, Jun 14, 2017 at 4:04 PM, Mitchell, John A <jamitch AT sandia.gov> wrote:

Hi,

I am using dynamic insertion of a chare array and do not know apriori the array length.

After calling 'doneInserting()' is there a way to get the array length without doing a collective reduction somehow?

Thanks.

John