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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LANG-1355) TimeZone.getTimeZone() in FastDateParser causes resource contention
Date Tue, 10 Oct 2017 16:27:00 GMT

    [ https://issues.apache.org/jira/browse/LANG-1355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16198912#comment-16198912
] 

ASF GitHub Bot commented on LANG-1355:
--------------------------------------

Github user PascalSchumacher commented on a diff in the pull request:

    https://github.com/apache/commons-lang/pull/296#discussion_r143781416
  
    --- Diff: src/main/java/org/apache/commons/lang3/time/FastTimeZone.java ---
    @@ -39,10 +43,11 @@ public static TimeZone getGmtTimeZone() {
     
         /**
          * Get a TimeZone, looking first for GMT custom ids, then falling back to Olson ids.
    -     * A GMT custom id has an optional prefix of GMT, followed by sign, hours digit(s),
optional
    -     * colon(':'), and optional minutes digits: <em>[GMT] (+|-) Hours [[:] Minutes]</em>
    +     * A GMT custom id can be 'Z', or 'UTC', or has an optional prefix of GMT,
    +     * followed by sign, hours digit(s), optional colon(':'), and optional minutes digits.
    +     * i.e. <em>[GMT] (+|-) Hours [[:] Minutes]</em>
          *
    -     * @param id A GMT custom id or Olsen id
    +     * @param id A GMT custom id (or Olson id
    --- End diff --
    
    Nitpick: either a superfluous `(` or a missing `)`


> TimeZone.getTimeZone() in FastDateParser causes resource contention
> -------------------------------------------------------------------
>
>                 Key: LANG-1355
>                 URL: https://issues.apache.org/jira/browse/LANG-1355
>             Project: Commons Lang
>          Issue Type: Bug
>          Components: lang.time.*
>    Affects Versions: 3.6
>         Environment: Windows
>            Reporter: Keith Boone
>            Assignee: Charles Honton
>   Original Estimate: 48h
>  Remaining Estimate: 48h
>
> Under heavy load we are seeing contention in FastDateParser.parse() on calls to TimeZone.getTimeZone().
 TimeZone.getTimeZone() is a synchronized static in the Oracle JVM.
> Our proposed solution is to add a class TimeZoneCache containing a single method getTimeZone()
which gets the requested time zone from a ConcurrentMap, and if not present, looks it up via
TimeZone.getTimeZone() and caches it before returning it.
> Then replace calls to TimeZone.getTimeZone() in FastDateParser ( and whereever else)
to calls to TimeZoneCache.getTimeZone().  
> The reason to add a separate class is because it can also be used by other applications
which heavily parse or format or do other things where TimeZone is repeatedly needed.
> Under extreme load we have seen an 50:1 improvement in calls to FastDateParser.parse().
 This saves about a ms/call in our test environment, and reduces contention.



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