JSPs stop working if their osgi module is restarted and direct.servlet.context.reload property is configured to false

Issue

• JSPs stop working if their osgi module is restarted and the direct servlet context reload functionality is disabled with the direct.servlet.context.reload=false setting.
• The issue is also reproduced in case:
  • You deploy a new osgi fragment module that overrides an existing JSP module (see JSP Overrides Using-OSGi Fragments) in a running Liferay environment.
  • You deploy a new version of an existing module that contains JSPs in a running Liferay environment.
• The following exception can be also thrown due to this issue:

  2018-01-29 05:30:59.053 ERROR [http-nio-8080-exec-7][IncludeTag:128] Current URL /group/control_panel/manage?p_p_id=com_liferay_server_admin_web_portlet_ServerAdminPortlet&p_p_lifecycle=0&p_p_state=maximized generates exception: null
  java.lang.NullPointerException
  	at com.liferay.taglib.servlet.PageContextWrapper.handlePageException(PageContextWrapper.java:173)
  	at org.apache.jsp.server_jsp._jspService(server_jsp:653)
  	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
  	at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
  	at com.liferay.portal.servlet.DirectRequestDispatcher.include(DirectRequestDispatcher.java:64)
  	at com.liferay.portal.servlet.ClassLoaderRequestDispatcherWrapper.doDispatch(ClassLoaderRequestDispatcherWrapper.java:78)
  	at com.liferay.portal.servlet.ClassLoaderRequestDispatcherWrapper.include(ClassLoaderRequestDispatcherWrapper.java:53)
  	at com.liferay.taglib.util.IncludeTag.includePage(IncludeTag.java:372)
  	at com.liferay.taglib.util.IncludeTag.include(IncludeTag.java:349)
  	at com.liferay.taglib.util.IncludeTag.doInclude(IncludeTag.java:202)
  	at com.liferay.taglib.util.IncludeTag.doEndTag(IncludeTag.java:86)
  	at org.apache.jsp.view_jsp._jspService(view_jsp:432)

Environment

• DXP 7.0
• DXP 7.1
• DXP 7.2
• DXP 7.3

Resolution

• Disabling the direct servlet context reload functionality with direct.servlet.context.reload=false is not compatible with any functionality that relies on the JSP dynamic reloading ability at runtime.
• If you have disabled it, any administrative operation that causes a JSP dynamic reloading at runtime will cause that JSP to stop working.
• Some of these operations are:
  • Manual stop / start of a module that contains a JSP file.
  • Deploying a new osgi module version of an existing module.
  • Deploying a new osgi fragment to override an existing JSP file of other module.
• To avoid this issue you have two options:
  • Always restart the application server after these operations in order to force a reload of the JSP file.
  • Remove the direct.servlet.context.reload=false property and enable the direct servlet context reload functionality.

Additional Information

• See the ticket LPS-77650 A blank page appears after restarting the modules which use "<liferay-util:include" in the jsp,jspf files, which wasn't considered a product issue and was closed as "won't fix"