|
Mark Waterbury asked: >However, here too, I would like to ask the question, >why "250" libraries? Why not raise the bar to, say, >500 or 1000 libraries? Why place "arbitrary" limits >on things like the "library list"? I didn't make this decision, but the answer in this case is simple: Performance. Not every resolution of a name to an object is going to succeed. In not a few cases, failed resolutions are even planned and the result will be the creation of the (not existing yet) object. The classic example of this is a simple "open for write" in a high level language like C or COBOL. If the file doesn't exist, it gets created. Well, how is create versus reuse typically found out? In OS/400, by resolving a system pointer using the library list. Five hundred library lookups is, even in 2001, a fair amount of time spent, especially for something that is reasonably routine. Now, to state the obvious, I suppose there are ways that the size of the list could be made unboundedly large. But, everyone makes decisions about this sort of stuff all the time whether one designs OS or App code for a living. Do we implement a fixed limit (cheaper to code, a bit faster to run, a bit easier to explain) or some very flexible scheme that is effectively unbounded, with uncertain or indescribable worst case failure conditions? Who really needs the limit "that big?" Do we do anyone a favor by inviting "abuse" of a given feature? Maybe an unlimited library list was the right call, but it wasn't obvious many years ago when this decision was undoubtedly made. For instance, VM had lived with a similar limit for its mini-disks for many years and still (so far as I know) does so. Larry W. Loen - Senior Java and iSeries Performance Analyst Dept HP4, Rochester MN Speaking on his own, as always +--- | This is the MI Programmers Mailing List! | To submit a new message, send your mail to MI400@midrange.com. | To subscribe to this list send email to MI400-SUB@midrange.com. | To unsubscribe from this list send email to MI400-UNSUB@midrange.com. | Questions should be directed to the list owner/operator: dr2@cssas400.com +---
As an Amazon Associate we earn from qualifying purchases.
This mailing list archive is Copyright 1997-2024 by midrange.com and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].
Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.