GitHub user prabhjyotsingh opened a pull request:
https://github.com/apache/zeppelin/pull/2711
ZEPPELIN-3112: Markdown interpreter fails with NPE
### What is this PR for?
Since pegdown-parser is not thread-safe while trying to run multiple
MarkDown paragraphs at once, sometimes it fails to render HTML.
Ref:
https://github.com/sirthias/pegdown/blob/master/src/main/java/org/pegdown/PegDownProcessor.java#L32
### What type of PR is it?
[Improvement]
### Todos
* [ ] - Task
### What is the Jira issue?
* [ZEPPELIN-3112](https://issues.apache.org/jira/browse/ZEPPELIN-3112)
### How should this be tested?
* This happens rarely, when you try to run all paragraph from UI which has
more the 5-6 `%md` paragraph. This is hard to reproduce in 0.8.0, but can
easily be done via 0.7.3.
* Have added test case to verify.
### Questions:
* Does the licenses files need update? N/A
* Is there breaking changes for older versions? N/A
* Does this needs documentation? N/A
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/prabhjyotsingh/zeppelin ZEPPELIN-3112
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/zeppelin/pull/2711.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 #2711
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commit 89e64188a5631d6e20d665794277afdd7ff5739e
Author: Prabhjyot Singh <prabhjyotsingh@...>
Date: 2017-12-20T12:39:04Z
ZEPPELIN-3112: call markdownToHtml in synchronized block
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