Data corruption with Nashorn + Handlebars and concurrent requests

[Sebastien Deleuze]

Hi,

I currently try to implement support for Script based templating in Spring
Framework [1] using Nashorn and template engines like Mustache or
Handlebars.

As discussed today on Twitter [2], I have some strange argument corruption
issues when using Nashorn + Handlebars with concurrent request. I am aware
of loadWithNewGlobal() but it seems I don't use it properly because I still
see the issue using it.

In order to make things simpler, I have created a repo project [3]. To make
it work, simply execute TestApplication main class.

MustacheJS seems to works with concurrent requests :
ab -n 5000 -c 4 http://localhost:8080/mustache/

But Handlebars seems to have some strange data corruption issues [4] (the
template contains <title>{{title}}</title> but <title>{title}}</title> is
printed in the log error message !!!) running both raw
and loadWithNewGlobal() alternatives:
ab -n 5000 -c 4 http://localhost:8080/handlebars/
ab -n 5000 -c 4 http://localhost:8080/handlebars/newglobal/
(the errors are displayed in the system output)

Could you please have a look to this repro project in order to see if:
 - There is a better way to use loadWithNewGlobal() (without the
intermediate render() function maybe)
 - If there is an issue in my code ?
 - If there is an issue in Nashorn ?

Running ab -n 5000 -c 1 http://localhost:8080/handlebars/ produces no
error, so this is really related to concurrency.

This is a feature we would like to ship with Spring Frameworks 4.2, so
making it running flawlessly is mandatory for us, I hope it will be
possible!

Thanks in advance for your help,
Sébastien Deleuze

[1] https://jira.spring.io/browse/SPR-12266
[2] https://twitter.com/sdeleuze/status/595586467298222082
[3] https://github.com/sdeleuze/script-engine-test
[4] jdk.nashorn.internal.runtime.ECMAException: Error: Parse error on line
3:
...ead>        <title>{title}}</title>
----------------------^
Expecting 'EOF', 'COMMENT', 'CONTENT', 'END_RAW_BLOCK', 'OPEN_RAW_BLOCK',
'OPEN_BLOCK', 'OPEN_INVERSE', 'OPEN_INVERSE_CHAIN', 'INVERSE',
'OPEN_ENDBLOCK', 'OPEN', 'OPEN_UNESCAPED', 'OPEN_PARTIAL', got 'INVALID'
at
jdk.nashorn.internal.scripts.Script$\^eval\_$2._L36$_L874$_L880$parseError(<eval>:1025)
at
jdk.nashorn.internal.scripts.Script$\^eval\_$2._L36$_L874$_L880$parse(<eval>:1077)
at
jdk.nashorn.internal.scripts.Script$\^eval\_$4._L36$_L1910$parse(<eval>:1936)
at
jdk.nashorn.internal.scripts.Script$\^eval\_$5._L36$_L1944$compile$compileInput(<eval>:2396)
at
jdk.nashorn.internal.scripts.Script$\^eval\_$4._L36$_L1944$compile$_L2403(<eval>:2405)
at jdk.nashorn.internal.scripts.Script$\^eval\_.renderHandlebars(<eval>:17)
at
jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:502)