GitHub user ueshin opened a pull request:
https://github.com/apache/spark/pull/17933
[SPARK-20588][SQL] Cache TimeZone instances per thread.
## What changes were proposed in this pull request?
Because the method `TimeZone.getTimeZone(String ID)` is synchronized on the
TimeZone class, concurrent call of this method will become a bottleneck.
This especially happens when casting from string value containing timezone
info to timestamp value, which uses `DateTimeUtils.stringToTimestamp()` and
gets TimeZone instance on the site.
This pr makes a cache of the generated TimeZone instances per thread to
avoid the synchronization.
## How was this patch tested?
Existing tests.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/ueshin/apache-spark issues/SPARK-20588
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17933.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #17933
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commit de79e50779c0f2e17ea26301ac7d1216b37331c9
Author: Takuya UESHIN <ues...@databricks.com>
Date: 2017-05-10T05:55:53Z
Cache TimeZone instances per thread.
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