[java] Parsing failed in ParseLock#doParse() java.io.IOException: Stream closed #4899
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Luckily, this was reproducible with pmd itself, by just running It turns out, that we run into a Java optimization: Opened Jar Files are cached and there is only one instance in the running JVM for each physically existing JarFile. Our ClasspathClassLoader is extending URLClassLoader for loading the bytecode class-files from the auxiliary classpath via Here's a reproducer of the issue (it uses import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLConnection;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.Semaphore;
class Scratch {
static Path jarFilePath = Path.of(System.getProperty("user.home"), ".m2/repository/net/sourceforge/pmd/pmd-core/7.0.0/pmd-core-7.0.0.jar");
private static class MyClassLoader extends URLClassLoader {
public MyClassLoader(URL[] urls, ClassLoader parent) {
super(urls, parent);
}
@Override
public void close() throws IOException {
super.close();
System.out.println(Thread.currentThread().getName() + ": Closed MyClassLoader");
}
}
private static class MyThread implements Runnable {
private final int number;
private final CyclicBarrier waitForDone;
private final Semaphore grapResource;
public MyThread(int number, CyclicBarrier waitForDone, Semaphore grapResource) {
this.number = number;
this.waitForDone = waitForDone;
this.grapResource = grapResource;
}
private void log(String message) {
System.out.println("%s: %s".formatted(Thread.currentThread().getName(), message));
}
@Override
public void run() {
try {
URL jarFileUrl = jarFilePath.toUri().toURL();
String pmdVersionResourcePath = "net/sourceforge/pmd/PMDVersion.class";
try (URLClassLoader loader = new MyClassLoader(new URL[]{jarFileUrl}, null)) {
InputStream stream;
// make sure, each threads gets the resource one after another, so that the underlying JarFile
// is definitely cached (if caching is enabled)
grapResource.acquire();
try {
stream = loader.getResourceAsStream(pmdVersionResourcePath);
if (stream == null) {
throw new RuntimeException("resource not found: " + pmdVersionResourcePath);
}
} finally {
grapResource.release();
}
// wait for the first thread to finish and close its URLClassLoader
if (number != 0) {
waitForDone.await();
}
byte[] bytes;
try (InputStream in = stream; ByteArrayOutputStream out = new ByteArrayOutputStream()) {
log("Reading now...");
in.transferTo(out);
bytes = out.toByteArray();
}
if (bytes.length != 2935) {
throw new IllegalStateException("Read error");
}
}
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
if (number == 0) {
// we are the first thread. Signal the other waiting threads so that
// they can continue. They should see now closed streams.
try {
waitForDone.await();
} catch (InterruptedException e) {
throw new RuntimeException(e);
} catch (BrokenBarrierException e) {
throw new RuntimeException(e);
}
}
}
}
}
public static void main(String[] args) throws InterruptedException, IOException {
System.out.println("Scratch");
// Disable caching...
//jarFilePath.toUri().toURL().openConnection().setDefaultUseCaches(false);
int numberOfThreads = 2;
CyclicBarrier waitForDone = new CyclicBarrier(numberOfThreads);
Semaphore grabResource = new Semaphore(1);
List<Thread> threads = new ArrayList<>(numberOfThreads);
for (int i = 0; i < numberOfThreads; i++) {
threads.add(new Thread(new MyThread(i, waitForDone, grabResource), "Thread" + i));
}
threads.forEach(Thread::start);
for (Thread thread : threads) {
thread.join();
}
}
}This gives the following output: The caching can be disabled globally by calling URLConnection#setDefaultUseCaches(false). I'm working on solution... |
Affects PMD Version:
PMD 7.0.0
Description:
Running maven build in multi-threaded mode
-TException Stacktrace:
Code Sample demonstrating the issue:
With current implementation the
doParse()can be called only once, socanReentershould returnfalseorclassReadershould be shared orInputStream.reset()should be called.Steps to reproduce:
Use maven multi-module project with lots of modules
mvn clean verify -T 2jdk21
maven 3.9.6
maven-pmd-plugin 3.21.2
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