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  1. JBoss Enterprise Application Platform
  2. JBEAP-13945

[GSS](7.2.0) NullPointerException happens at ELEvaluator.parseExpressionString() due to a concurrency issue

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    • Bug
    • Resolution: Obsolete
    • Major
    • None
    • 7.0.8.GA
    • EE
    • None
    • Hide

      1. Download and extract the attached example.zip
      2. Build and deploy example.war to EAP 7

      mvn clean package

      3. Access two JSPs (index.jsp and index2.jsp) to triger jsp compile almost at the same time. For example:

      curl http://localhost:8080/example/index.jsp & curl http://localhost:8080/example/index2.jsp &

      Then, you will see the following NPE high probability. Of cource, this is a timing issue, so you may not be able to reproduce the issue.

      You can use a byteman rule to reproduce the issue more reliabily. The byteman rule just invokes Thread.sleep once in 2 times.

      Show
      1. Download and extract the attached example.zip 2. Build and deploy example.war to EAP 7 mvn clean package 3. Access two JSPs (index.jsp and index2.jsp) to triger jsp compile almost at the same time. For example: curl http: //localhost:8080/example/index.jsp & curl http://localhost:8080/example/index2.jsp & Then, you will see the following NPE high probability. Of cource, this is a timing issue, so you may not be able to reproduce the issue. You can use a byteman rule to reproduce the issue more reliabily. The byteman rule just invokes Thread.sleep once in 2 times.

    Description

      The following NullPointerException happens at ELEvaluator.parseExpressionString() due to a concurrency issue.

      Once this NPE happens, you will see same NPE every time when accessing the failed JSP. (If development="true" is configured in <jsp-config>, recompile can happen in the next access, so NPE can disappear after successful compilation in the next access.)

      ERROR [io.undertow.request] (default task-4) UT005023: Exception handling request to /example/index.jsp: org.apache.jasper.JasperException: JBWEB004001: Unable to compile class for JSP
    at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:667) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:402) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:346) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [jboss-servlet-api_3.1_spec-1.0.0.Final-redhat-1.jar:1.0.0.Final-redhat-1]
    ...(snip)...
    ...
Caused by: java.lang.NullPointerException
    at org.apache.taglibs.standard.lang.jstl.ELEvaluator.parseExpressionString(ELEvaluator.java:276) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.taglibs.standard.lang.jstl.Evaluator.validate(Evaluator.java:71) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager.validate(ExpressionEvaluatorManager.java:131) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.taglibs.standard.tlv.el.ValidationUtil.validateExpression(ValidationUtil.java:26) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.taglibs.standard.tlv.el.JstlELCoreTLV.validateExpression(JstlELCoreTLV.java:26) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.taglibs.standard.tlv.JstlCoreTLV$Handler.startElement(JstlCoreTLV.java:158) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.xerces.parsers.AbstractSAXParser.startElement(AbstractSAXParser.java:498)
    at org.apache.xerces.parsers.AbstractXMLDocumentParser.emptyElement(AbstractXMLDocumentParser.java:180)
    at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:275)
    at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(XMLDocumentFragmentScannerImpl.java:1653)
    at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:324)
    at org.apache.xerces.parsers.XML11Configuration.parse(XML11Configuration.java:875)
    at org.apache.xerces.parsers.XML11Configuration.parse(XML11Configuration.java:798)
    at org.apache.xerces.parsers.XMLParser.parse(XMLParser.java:108)
    at org.apache.xerces.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1198)
    at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:564)
    at org.apache.taglibs.standard.tlv.JstlBaseTLV.validate(JstlBaseTLV.java:158) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.taglibs.standard.tlv.JstlCoreTLV.validate(JstlCoreTLV.java:97) [jboss-jstl-api_1.2_spec-1.1.3.Final-redhat-1.jar:1.1.3.Final-redhat-1]
    at org.apache.jasper.compiler.TagLibraryInfoImpl.validate(TagLibraryInfoImpl.java:552) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.compiler.Validator.validateXmlView(Validator.java:1856) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.compiler.Validator.validateExDirectives(Validator.java:1825) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:218) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:354) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:334) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:321) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:652) [jastow-2.0.0.Final-redhat-1.jar:2.0.0.Final-redhat-1]
    ... 61 more

      252     public Object parseExpressionString(String pExpressionString)
253             throws ELException {
254         // See if it's an empty String
255         if (pExpressionString.length() == 0) {
256             return "";
257         }
258
259         if (!(mBypassCache) && (sCachedExpressionStrings == null)) {
260             createExpressionStringMap();
261         }
262
263         // See if it's in the cache
264         Object ret =
265                 mBypassCache ?
266                         null :
267                         sCachedExpressionStrings.get(pExpressionString);
268
269         if (ret == null) {
270             // Parse the expression
271             Reader r = new StringReader(pExpressionString);
272             ELParser parser = new ELParser(r);
273             try {
274                 ret = parser.ExpressionString();
275                 if (!mBypassCache) {
276                     sCachedExpressionStrings.put(pExpressionString, ret); // <- NPE occurred at here
277                 }
278             }
279             catch (ParseException exc) {
280                 throw new ELException
281                         (formatParseException(pExpressionString,
282                                 exc));
283             }
284             catch (TokenMgrError exc) {
285                 // Note - this should never be reached, since the parser is
286                 // constructed to tokenize any input (illegal inputs get
287                 // parsed to <BADLY_ESCAPED_STRING_LITERAL> or
288                 // <ILLEGAL_CHARACTER>
289                 throw new ELException(exc.getMessage());
290             }
291         }
292         return ret;
293     }

      ~~~
 51     /**
 52      * The singleton instance of the evaluator *
 53      */
 54     static ELEvaluator sEvaluator =
 55             new ELEvaluator
 56                     (new JSTLVariableResolver());
 :
 62     /**
 63      * Translation time validation of an attribute value.  This method
 64      * will return a null String if the attribute value is valid;
 65      * otherwise an error message.
 66      */
 67     public String validate(String pAttributeName,
 68                            String pAttributeValue) {
 69         try {
 70             sEvaluator.setBypassCache(true);   // <-- mBypassCache is set to true before invoking parseExpressionString()
 71             sEvaluator.parseExpressionString(pAttributeValue);
 72             sEvaluator.setBypassCache(false);
 73             return null;
 74         }
 75         catch (ELException exc) {

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          Bug - A problem that impairs or prevents the functions of the product. JBEAP-13942 [GSS](7.0.z) NullPointerException happens at ELEvaluator.parseExpressionString() due to a concurrency issue

          • Major - To be worked after higher priority work items are addressed. When the severity is high and the effort to change it is low to moderate, this term is chosen. Issues in this category likely have an existing workaround but implementation or execution may be non-trivial.
          • Closed

          Bug - A problem that impairs or prevents the functions of the product. JBEAP-13944 [GSS](7.1.z) NullPointerException happens at ELEvaluator.parseExpressionString() due to a concurrency issue

          • Major - To be worked after higher priority work items are addressed. When the severity is high and the effort to change it is low to moderate, this term is chosen. Issues in this category likely have an existing workaround but implementation or execution may be non-trivial.
          • Closed
          is incorporated by

          Bug - A problem that impairs or prevents the functions of the product. JBEAP-13944 [GSS](7.1.z) NullPointerException happens at ELEvaluator.parseExpressionString() due to a concurrency issue

          • Major - To be worked after higher priority work items are addressed. When the severity is high and the effort to change it is low to moderate, this term is chosen. Issues in this category likely have an existing workaround but implementation or execution may be non-trivial.
          • Closed
          links to

          Web Link KCS 3291171

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              thofman Tomas Hofman
              rhn-support-mmiura Masafumi Miura
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                Created:
                Updated:
                Resolved: