[ http://jira.qos.ch/browse/LBCLASSIC-36?page=com.atlassian.jira.plugin.system... ] Joern Huxhorn commented on LBCLASSIC-36: ---------------------------------------- Well, the above test looks like this from within IDEA: Raw - JDK: 4992 ns Joda: 5533 ns - Difference: -10.837339% Synchronized DateFormat: 0.4826 seconds Unsynchronized DateFormat: 1.7025 seconds ThreadLocal DateFormat: 0.1858 seconds Joda DateTimeFormatter: 0.0908 seconds And values are fluctuating quite a bit on reruns, that's why I'm asking... Raw - JDK: 4864 ns Joda: 5348 ns - Difference: -9.950658% Synchronized DateFormat: 0.4799 seconds Unsynchronized DateFormat: 1.5900 seconds ThreadLocal DateFormat: 0.1806 seconds Joda DateTimeFormatter: 0.1252 seconds Raw - JDK: 5030 ns Joda: 5719 ns - Difference: -13.697813% Synchronized DateFormat: 0.4813 seconds Unsynchronized DateFormat: 1.6982 seconds ThreadLocal DateFormat: 0.1870 seconds Joda DateTimeFormatter: 0.0838 seconds ...

Synchronization of SimpleDateFormat object in DateConverter -----------------------------------------------------------

Key: LBCLASSIC-36 URL: http://jira.qos.ch/browse/LBCLASSIC-36 Project: logback-classic Issue Type: Bug Components: Other Affects Versions: unspecified Environment: Operating System: All Platform: All Reporter: Anders Hammar Assignee: Ceki Gulcu Attachments: DateConverter_patch.java, DateFormatPerfTest.java, dateformattest.zip, DoubleCheckedLocking.patch

According to the API documentation of SimpleDateFormat, date formats are not synchronized and it is recommended to create separate format instances for each thread. However, a possibly simpler (mer efficient) solution would be to synchronize on the SimpleDateFormat object in the convert() method to prevent two threads to access it concurrently.

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