java - 同时使用 XPathExpression
问题描述
我正在尝试同时使用 XPathExpression，但得到“org.xml.sax.SAXException：解析时可能不会调用 FWK005 解析”。使用 ThreadLocal 没有帮助，即使为每个调用创建了新的 XPathExpression，它也会失败。此 Junit 测试重现问题：
package testxpath;
import java.io.StringReader;
import java.util.stream.IntStream;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import org.junit.jupiter.api.Test;
import org.xml.sax.InputSource;
import lombok.SneakyThrows;
class ConcurrentXpathTest {
private static final String XPATH = "//*[(local-name()='Node')]";
private static final String XML = "<Node>Something</Node>";
@Test
void testConcurrentXpath() {
IntStream.range(0, 10000)
.parallel()
.forEach(v -> parse());
}
@SneakyThrows
private void parse() {
XPathExpression xPathExpression = XPathFactory.newInstance().newXPath().compile(XPATH);
xPathExpression.evaluate(new InputSource(new StringReader(XML)), XPathConstants.NODESET);
}
}
如何解决这个问题？也许建议一些替代库。
堆栈跟踪：
org.xml.sax.SAXException: FWK005 parse may not be called while parsing.
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:271)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)
at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:291)
at com.corelogic.clp.tel2.gateway.services.ConcurrentXpathTest.parse(ConcurrentXpathTest.java:43)
at com.corelogic.clp.tel2.gateway.services.ConcurrentXpathTest.lambda$testConcurrentXpath$0(ConcurrentXpathTest.java:37)
at java.util.stream.ForEachOps$ForEachOp$OfInt.accept(ForEachOps.java:205)
at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:110)
at java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:693)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.ForEachOps$ForEachTask.compute(ForEachOps.java:291)
at java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:731)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
--------------- linked to ------------------
javax.xml.xpath.XPathExpressionException: org.xml.sax.SAXException: FWK005 parse may not be called while parsing.
at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:294)
at com.corelogic.clp.tel2.gateway.services.ConcurrentXpathTest.parse(ConcurrentXpathTest.java:43)
at com.corelogic.clp.tel2.gateway.services.ConcurrentXpathTest.lambda$testConcurrentXpath$0(ConcurrentXpathTest.java:37)
at java.util.stream.ForEachOps$ForEachOp$OfInt.accept(ForEachOps.java:205)
at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:110)
at java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:693)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.ForEachOps$ForEachTask.compute(ForEachOps.java:291)
at java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:731)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
Caused by: org.xml.sax.SAXException: FWK005 parse may not be called while parsing.
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:271)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)
at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:291)
... 12 more
--------------- linked to ------------------
javax.xml.xpath.XPathExpressionException: javax.xml.xpath.XPathExpressionException: org.xml.sax.SAXException: FWK005 parse may not be called while parsing.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at java.util.concurrent.ForkJoinTask.getThrowableException(ForkJoinTask.java:593)
at java.util.concurrent.ForkJoinTask.reportException(ForkJoinTask.java:677)
at java.util.concurrent.ForkJoinTask.invoke(ForkJoinTask.java:735)
at java.util.stream.ForEachOps$ForEachOp.evaluateParallel(ForEachOps.java:160)
at java.util.stream.ForEachOps$ForEachOp$OfInt.evaluateParallel(ForEachOps.java:189)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:233)
at java.util.stream.IntPipeline.forEach(IntPipeline.java:404)
at java.util.stream.IntPipeline$Head.forEach(IntPipeline.java:560)
at com.corelogic.clp.tel2.gateway.services.ConcurrentXpathTest.testConcurrentXpath(ConcurrentXpathTest.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:532)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:115)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:171)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:167)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:114)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:59)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$4(NodeTestTask.java:108)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:98)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:74)
at java.util.ArrayList.forEach(ArrayList.java:1257)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$4(NodeTestTask.java:112)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:98)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:74)
at java.util.ArrayList.forEach(ArrayList.java:1257)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$4(NodeTestTask.java:112)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:98)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:74)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:220)
at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:188)
at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:202)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:181)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:128)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)
Caused by: javax.xml.xpath.XPathExpressionException: org.xml.sax.SAXException: FWK005 parse may not be called while parsing.
at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:294)
at com.corelogic.clp.tel2.gateway.services.ConcurrentXpathTest.parse(ConcurrentXpathTest.java:43)
at com.corelogic.clp.tel2.gateway.services.ConcurrentXpathTest.lambda$testConcurrentXpath$0(ConcurrentXpathTest.java:37)
at java.util.stream.ForEachOps$ForEachOp$OfInt.accept(ForEachOps.java:205)
at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:110)
at java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:693)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.ForEachOps$ForEachTask.compute(ForEachOps.java:291)
at java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:731)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
Caused by: org.xml.sax.SAXException: FWK005 parse may not be called while parsing.
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:271)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)
at com.sun.org.apache.xpath.internal.jaxp.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:291)
... 12 more
解决方案
这是由于某些 Xerces 版本中的错误，甚至是 JDK/JRE 附带的版本。
请参阅此错误报告。据说它在 Java 9+ 附带的默认实现中已修复，但您可能对 1.8 不走运。
检查您正在使用的 Xerces 实现可能是值得的。
我们偶然发现了与 Apache Xalan 2.7.1 捆绑在一起的 Xerces。返回的对象DocumentBuilderFactory.newInstance()似乎包含非线程安全的内部状态，但在实例之间共享（或者它产生其他表现出相同的对象）。这似乎是异常的根本原因。
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