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IDProjectCategoryView StatusDate SubmittedLast Update
0003942OCamlOCaml generalpublic2005-12-30 17:092006-01-18 17:37
Reportermottl 
Assigned To 
PrioritynormalSeverityfeatureReproducibilityN/A
StatusacknowledgedResolutionopen 
PlatformOSOS Version
Product Version3.09.0 
Target VersionFixed in Version 
Summary0003942: More detailed specification of the behaviour of Unix.select
DescriptionAccording to the C-implementation of "Unix.select", file descriptors in ready sets are returned in the reverse order in which they appeared in the argument lists. Could this please be explicitly specified as a guarantee in the documentation?

This way the user may be able to find out much more quickly (in O(1)) whether I/O is possible on a particular descriptor in a large set by simply making it the last one in the argument list and checking the first returned descriptor for equivalence.
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-  Notes
(0003495)
doligez (administrator)
2006-01-05 14:19

IMO, if you want to know whether I/O is possible on a particular descriptor, the proper
solution is to call select with only that descriptor.
(0003513)
mottl (reporter)
2006-01-18 17:37

The reason why this is not a good solution for us is, because we are implementing a messaging library that should have very low latency and very high throughput (> 100000 msgs/sec). System calls are extremely expensive and even just one superfluous call more quite noticably lowers throughput. Unfortunately, Linux still doesn't have a reasonable implementation of asynchronous I/O, which would be the optimum solution for this problem.

- Issue History
Date Modified Username Field Change
2005-12-30 17:09 mottl New Issue
2006-01-05 14:19 doligez Note Added: 0003495
2006-01-05 14:19 doligez Severity text => feature
2006-01-05 14:19 doligez Status new => acknowledged
2006-01-18 17:37 mottl Note Added: 0003513


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