[tz] tzdata2016g missing version information
eggert at cs.ucla.edu
Fri Sep 30 15:43:00 UTC 2016
On 09/29/2016 01:21 AM, Martin Burnicki wrote:
> are the changes detected automatically at runtime
> and become effective for the application when a new version of the TZ DB
> is installed, or only after the application or run-time library is reloaded?
This depends on the library and on the application. Typically reloading
is required, as this improves efficiency in the typical case. That's how
the reference code works.
The issue is not limited to updating tzdata version. It can also occur
when the system changes the wall-clock time zone, e.g., by changing
/etc/localtime to point to a different file. On mobile devices this can
occur when you (say) cross the Trammell Bridge from Blountstown to
Bristol in Florida, to go from "slow time" (CST) to "fast time" (EST).
Some applications do tricks like 'setenv ("TZ", getenv ("TZ"))' to
cajole the library into the heavyweight operation of reloading a changed
zone file. The code is actually more complicated than that, as some
libraries notice that you haven't actually changed TZ and so do nothing.
My source for "slow" and "fast time":
Klinkenberg J. Real Florida: time and time again. St Petersburg Times
More information about the tz