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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 09:01:00 GMT

    [ https://issues.apache.org/jira/browse/LANG-1355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16198381#comment-16198381
] 

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

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

    https://github.com/apache/commons-lang/pull/296#discussion_r143663160
  
    --- Diff: src/main/java/org/apache/commons/lang3/time/FastTimeZone.java ---
    @@ -0,0 +1,90 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one or more
    + * contributor license agreements.  See the NOTICE file distributed with
    + * this work for additional information regarding copyright ownership.
    + * The ASF licenses this file to You under the Apache License, Version 2.0
    + * (the "License"); you may not use this file except in compliance with
    + * the License.  You may obtain a copy of the License at
    + *
    + *      http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.commons.lang3.time;
    +
    +import java.util.TimeZone;
    +import java.util.regex.Matcher;
    +import java.util.regex.Pattern;
    +
    +/**
    + * Faster methods to produce custom time zones.
    + *
    + * @since 3.7
    + */
    +public class FastTimeZone {
    --- End diff --
    
    Do we need a private constructor to prevent instantiation of FastTimeZone? It seems to
contain only static methods. Not sure if that's the intended design. But noticed it while
looking at the cobertura report (which is looking great).


> 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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