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Top Forums UNIX for Advanced & Expert Users Xt timer call, XtAppAddTimeout, hangs on system clock jump backwards Post 303020476 by altrefrain on Friday 20th of July 2018 12:44:33 PM
Old 07-20-2018
Question Xt timer call, XtAppAddTimeout, hangs on system clock jump backwards

Hi, I've got an issue which I've been 'google-fu'ing without much luck. We have a legacy program which has been plagued by an issue for a long time and I've been tasked to investigate/fix.

The program uses XMotif2.1 (required due to dependency on an old GUI designer) and runs on a RHEL7 machine (previously RHEL 5 and before that RHEL4). Normal GUI event processing relies on a re-entrant Xt callback using the XtAppAddTimeout call. This works fine, unless the system clock is set backwards, which occurs due during an NTP sync of the system (which can happen at any point during the program). When this occurs, it appears as though the program is frozen. According to my research, the way Xt handles timeouts is by determining the expiration time (system time + expiration interval) and waiting until that absolute time is reached, rather than using a monotonic clock. So, if the timer is waiting for a second to elapse, but during the wait the system time is set backwards by 18 minutes, the timer will wait for 18 minutes and 1 second before going off (i.e. reach the original expected expiration time).

I've found very little information on the web about others experiencing this issue and any suggestions for a solution. We've tried detecting the time jump in a separate thread and then attempting to cancel, via XtRemoveTimeout, and then restart the timer. But, we haven't had much luck. The best solution I've heard so far was to manage the timer outside the X event loop and use XtAppAddWorkProc instead.

This might be a long shot. But, does anyone have any experience with this that could provide some insight. TIA
 

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Net::Google::Code::Issue(3pm)				User Contributed Perl Documentation			     Net::Google::Code::Issue(3pm)

NAME
Net::Google::Code::Issue - Google Code Issue SYNOPSIS
use Net::Google::Code::Issue; my $issue = Net::Google::Code::Issue->new( project => 'net-google-code' ); $issue->load(42); DESCRIPTION
ATTRIBUTES
project project name email, password user's email and password id status owner reporter reported merged stars closed cc summary description labels comments attachments INTERFACE
load parse updated the last comment's date. create comment, summary, status, owner, cc, labels, files. update comment, summary, status, owner, merge_into, cc, labels, blocked_on, files. list( q => '', can => '', author => '', id => '', label => '', max_results => '', owner => '', published_min => '', published_max => '', updated_min => '', updated_max => '', start_index => '' ) google's api way to get/search issues return a list of loaded issues in list context, a ref to the list otherwise. load_comments google's api way to get and load comments( no scraping is done here ) parse_hybrid when $USE_HYBRID is true, we will try to load issue with the google's official api, but as the api is not complete, we still need to do scraping to load something( e.g. attachments ), this method is used to do this. AUTHOR
sunnavy "<sunnavy@bestpractical.com>" LICENCE AND COPYRIGHT
Copyright 2008-2010 Best Practical Solutions. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.10.1 2010-04-28 Net::Google::Code::Issue(3pm)
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