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Tristan Tarrant commented on LOG4J2-3672: ----------------------------------------- Here is a screenshot containing a stack trace leading up to the invocation of {{DateFormatSymbols.getZoneStrings()}} !stacktrace.png! > 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 > Attachments: stacktrace.png > > Time Spent: 2h 10m > 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. > -- This message was sent by Atlassian Jira (v8.20.10#820010)