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https://issues.apache.org/jira/browse/LOG4J2-3672?focusedWorklogId=884727&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-884727
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ASF GitHub Bot logged work on LOG4J2-3672:
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Author: ASF GitHub Bot
Created on: 12/Oct/23 10:29
Start Date: 12/Oct/23 10:29
Worklog Time Spent: 10m
Work Description: tristantarrant commented on PR #1848:
URL: https://github.com/apache/logging-log4j2/pull/1848#issuecomment-1759346762
I have reworked the PR to lazily initialize the TZ names only if a the date
pattern uses a non-GMT/RFC822-style name. A WARNing will be logged once in this
case.
My idea about implementing an alternate `ZoneRulesProvider` is hindered by
https://bugs.openjdk.org/browse/JDK-8303899 :(
Issue Time Tracking
-------------------
Worklog Id: (was: 884727)
Time Spent: 40m (was: 0.5h)
> Avoid invoking DateFormatSymbols.getZoneStrings() in FastDateParser
> -------------------------------------------------------------------
>
> Key: LOG4J2-3672
> URL: https://issues.apache.org/jira/browse/LOG4J2-3672
> Project: Log4j 2
> Issue Type: Bug
> Reporter: Tristan Tarrant
> Priority: Major
> Time Spent: 40m
> Remaining Estimate: 0h
>
> {{FastDateParser}} uses {{DateFormatSymbols.getZoneStrings()}} to construct a
> table of all possible timezone names to be used in parsing date patterns in
> pattern layouts.
> Unfortunately the above call (and the equivalent call used by the JDK's
> {{SimpleDateFormat)}} causes initialization and caching of all timezones,
> resulting in a ~3MB heap overhead on x86_64. The following table summarizes
> the cost of triggering the caching of all timezones, including the number of
> instances of some related types and the amount of extra heap required.
>
> || ||LocalDateTime||LocalDate||ZoneInfo||ZoneOffset||Heap delta||
> |Baseline (no TZ calls)|180|0|0| | |
> |Single timezone|180|0|0|0|298|
> |DateFormatSymbols.getZoneStrings()|57076|32212|602|1455|3760106|
> |TimeZone.getAvailableIds() + TimeZone.getName()|36678|21674|632|1155|3024946|
> |TimeZone.getAvalableIDs()|180|0|632|0|452578|
> By avoiding constructions of such tables, and relying only on
> {{{}FastDateParser{}}}'s support for RFC-822 and GMT-style timezone names, we
> can avoid allocating the extra heap.
>
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