Set Silo's DB_NFILES compile-time parameter at runtime

Brian Rujiuz and Matt O'Brian requested this. Currently, Silo places an upper limit on maximum number of concurrently opened files. That number is 256 and it is set at compile time. First, I have no idea why 256 was chosen. It could be a value that was appropriate for machines that existed when Silo was first being written about 20 years ago. Most systems place an upper limit on total number of open files (descriptors) at 1024 or above. We can't get around that limit. But, Silo could be modified to use whatever the system limit as its own internal limit instead of a hard-coded 256.

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Ticket number: 646
Status: New
Project: VisIt
Tracker: Feature
Priority: Normal
Subject: Set Silo's DB_NFILES compile-time parameter at runtime
Assigned to: -
Category: -
Target version: -
Author: Mark Miller
Start: 03/08/2011
Due date:
% Done: 0%
Estimated time: 4.00 hours
Created: 03/08/2011 06:52 pm
Updated:
Likelihood:
Severity:
Found in version:
Impact: 2 - Low
Expected Use: 2 - Rare
OS: All
Support Group: Any
Description:
Brian Rujiuz and Matt O'Brian requested this. Currently, Silo places an upper limit on maximum number of concurrently opened files. That number is 256 and it is set at compile time. First, I have no idea why 256 was chosen. It could be a value that was appropriate for machines that existed when Silo was first being written about 20 years ago. Most systems place an upper limit on total number of open files (descriptors) at 1024 or above. We can't get around that limit. But, Silo could be modified to use whatever the system limit as its own internal limit instead of a hard-coded 256.

Comments:

Search the source for the DB_NFILES compile-time parameter and the code that enforces the concurrent open-file limit. Check how the system's file-descriptor limit can be obtained across supported systems, then verify that Silo uses that limit instead of the hard-coded 256 without exceeding the operating-system maximum.