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https://issues.apache.org/jira/browse/LANG-1355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16198380#comment-16198380
]
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_r143660909
--- 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 {
+
+ private static final TimeZone GREENWICH = new GmtTimeZone(false, 0, 0);
+
+ /**
+ * Get the GMT TimeZone.
+ * @return A TimeZone with a raw offset of zero.
+ */
+ public static TimeZone getGmtTimeZone() {
+ return GREENWICH;
+ }
+
+ /**
+ * 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>
+ *
+ * @param id A GMT custom id or Olsen id
+ * @return A timezone
+ */
+ public static TimeZone getTimeZone(String id) {
+ TimeZone tz = getGmtTimeZone(id);
+ if (tz != null) {
+ return tz;
+ }
+ return TimeZone.getTimeZone(id);
+ }
+
+ private static final Pattern GMT_PATTERN =
Pattern.compile("^(?:(?i)GMT)?([+-])?(\\d\\d?)?(:?(\\d\\d?))?$");
+
+ /**
+ * Get a TimeZone with GMT offsets. A GMT offset must be either 'Z'
or match
+ * (GMT)? hh?(:?mm?)?, where h and m are digits representing hours and
minutes.
--- End diff --
Maybe instead of
> A GMT offset must be either 'Z' or match (GMT)? hh?(:?mm?)?
It should be
> A GMT offset must be 'Z', or 'UTC', or match (GMT)? hh?(:?mm?)?
?
> 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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