Portlet body doesn't display with an invalid FreeMarker template if set asyncRenderTimeout in config file

• Type: Regression Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.3.X, Master
• Fix Version/s: 7.3.X, Master
• Component/s: Portal Services > Templates Engine
• Labels:
  • QA-AUTOMATION
• Branch Version/s:
  7.3.x
• Backported to Branch:
  Committed
• Fix Priority: 3
• Last Working Version:
  7.3.10 DXP GA1
• Git Pull Request: https://github.com/shuyangzhou/liferay-portal/pull/9691
• QA Test Name:
  • LocalFile.TemplateRCE#ViewInstanceManager
  • LocalFile.TemplateRCE#ViewInstanceManagerWildfly
  • LocalFile.TemplateRCE#ViewServletContext
  • LocalFile.TemplateRCE#ViewSpringBeans
• QA Test Score: 16

Steps to Reproduce:

1. Add config file com.liferay.portal.template.freemarker.configuration.FreeMarkerEngineConfiguration.config in liferay.home/osgi/configs, and add property asyncRenderTimeout=L"7200000" in it.
2. Start portal.
3. Go to Content & Data > Web Content.
4. Add a new structure.
5. Add a new template for the structure with below script:

   <#assign ac=Application['org.springframework.web.context.WebApplicationContext.ROOT']>
   <#list ac.getBeanDefinitionNames() as item>
   	<p><b>${item}</b></p>
   </#list>
   

6. Add Web Content Display portlet into a page.
7. Add a new content of the created structure and template.

Expected Results:
Template error should display in Web Content portlet.

Actual Results:
Portlet body doesn't display.

Note:
When preview the web content in Web Content admin, error "Web Content is temporarily unavailable. " occurred.

Reproduced on:
Tomcat 9.0.37 + MySQL 5.7. Portal master DXP GIT ID: dab7ad790ee947a2abc6cc6b656a1caa46943ac5.