commit 67100bc1ee3d582404def99fc7eb8cac23debc7c Author: Karsten Loesing <karsten.loesing@gmx.net> Date: Wed May 28 10:08:05 2014 +0200 Use a single DateFormat per thread and format. DateFormat is not thread-safe, and creating a new instance every time we need one only wastes CPU time. Make sure that there's a single instance per thread and format that the thread can use whenever it wants. --- src/org/torproject/onionoo/DateTimeHelper.java | 35 ++++++++++++++++++------ 1 file changed, 26 insertions(+), 9 deletions(-) diff --git a/src/org/torproject/onionoo/DateTimeHelper.java b/src/org/torproject/onionoo/DateTimeHelper.java index 4158894..41ac70b 100644 --- a/src/org/torproject/onionoo/DateTimeHelper.java +++ b/src/org/torproject/onionoo/DateTimeHelper.java @@ -5,6 +5,8 @@ package org.torproject.onionoo; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; +import java.util.HashMap; +import java.util.Map; import java.util.TimeZone; public class DateTimeHelper { @@ -40,16 +42,31 @@ public class DateTimeHelper { public static final String DATEHOUR_NOSPACE_FORMAT = "yyyy-MM-dd-HH"; + private static ThreadLocal<Map<String, DateFormat>> dateFormats = + new ThreadLocal<Map<String, DateFormat>> () { + public Map<String, DateFormat> get() { + return super.get(); + } + protected Map<String, DateFormat> initialValue() { + return new HashMap<String, DateFormat>(); + } + public void remove() { + super.remove(); + } + public void set(Map<String, DateFormat> value) { + super.set(value); + } + }; + private static DateFormat getDateFormat(String format) { - /* TODO We're creating a new SimpleDateFormat instance here, because - * we can't share a single instance per date format between multiple - * threads. A better solution would be to share a single instance per - * date format and thread, or to share an instance of a thread-safe - * alternative per date format. */ - DateFormat dateFormat = new SimpleDateFormat(format); - dateFormat.setLenient(false); - dateFormat.setTimeZone(TimeZone.getTimeZone("UTC")); - return dateFormat; + Map<String, DateFormat> threadDateFormats = dateFormats.get(); + if (!threadDateFormats.containsKey(format)) { + DateFormat dateFormat = new SimpleDateFormat(format); + dateFormat.setLenient(false); + dateFormat.setTimeZone(TimeZone.getTimeZone("UTC")); + threadDateFormats.put(format, dateFormat); + } + return threadDateFormats.get(format); } public static String format(long millis, String format) {