[JSR310 M7 Review request] 8007572: Replace existing jdk timezone data at <java.home>/lib/zi with JSR310's tzdb. (original) (raw)

Erik Joelsson erik.joelsson at oracle.com
Fri Feb 8 09:51:58 UTC 2013

The build part of this review looks good to me.

/Erik

On 2013-02-07 19:31, Xueming Shen wrote:

Hi,

8007572: Replace existing jdk timezone data at <java.home>/lib/zi with JSR310's tzdb. Webrev: http://cr.openjdk.java.net/~sherman/8007572/ Note: JDK/JRE has been using the time zone data at <java.home>/lib/zi for j.u.TimeZone since JDK 1.4.0 [1]. JSR310 has introduced in its own time zone data file/format <java.home>lib/tzdb.jar to provide the time zone data support for its new java.time date-time classes. So we now have two different time zone data files in different formats (though from the same time zone data source, Olson tz data, now the IANA Time Zone Datebase) to support two sets of date-time APIs (java.util date-time classes and java.time date-time classes) in one JDK/JRE, which definitely will add the maintenance burden going forward, given the fact that we will have to update/distribute the latest tzdb data in JDK/JRE periodically [2]. Also the current way the time-zone data is being distributed/installed (at <java.home>/lib.zi, as individual file for each time zone) has been a footprint concern for some configurations, especially the small embedded environment. The JEP151 [3] was originally submitted to propose to store the time-zone data more efficiently into a single compressed file. The JEP 151 has been withdrawn since, with the assumption that JDK 8 may replace the "zi" data with the much smaller JSR310 tzdb data file. As indicated in JEP151, current installed "zi" directory probably takes up 1M of disk-space with the 0.5k default file-system-block-size. Even with the proposed "store in one single compressed file" approach, it will still take about 250K space for all tzdb data in "zi" directory. JSR310 tzdb data file however is much smaller. It is around 40K for compressed and 100k uncompressed, for the same tz data. The proposed change is to share the JSR310 time zone data tzdb.jar with j.u.TimeZone by converting the JSR310 tzdb data completely (bits to bits compatible) at runtime into the internal data structure that j.u.TimeZone needs for its time zone data functionality/needs. Thanks! -Sherman [1] https://jbs.oracle.com/bugs/browse/JDK-4230123 [2] http://www.oracle.com/technetwork/java/javase/tzupdater-readme-136440.html [3] http://openjdk.java.net/jeps/151

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